阅读说明：本技术 一种临界固溶和临界始于高温交变时效与退火热处理方法 (Critical solid solution and critical high-temperature alternative aging and annealing heat treatment method ) 是由 李志广 李晓霞 张树利 马强 安文忠 王东军 于 2020-12-07 设计创作，主要内容包括：本发明提供一种临界固溶和临界始于高温交变时效与退火热处理方法,包括：临界固溶热处理过程和临界始于高温交变时效与退火热处理过程。本发明的方案具有技术可行性、工艺适应性、质量可靠性、经济合理性、使用安全性,可有效扬长避短了奥氏体不锈钢传统主流热处理方法的优缺点,从根本上解决了现有奥氏体不锈钢热处理“质量稳定性差、合格品率低、硬度偏低、力学性能低与一致性差、抗变色锈蚀能力差、加热时间长、效率低、热处理设备加热可靠性差与高温元器件使用寿命低以及成本高”等“一长一高四差五低”特有热处理技术难题,尤其适用于奥氏体不锈钢在钢厂和制造厂所涉及的冶炼、轧钢、锻造和热处理等热加工工程技术领域。(The invention provides a method for alternative aging and annealing heat treatment of critical solid solution and critical starting high temperature, which comprises the following steps: the critical solution heat treatment process and critical process start from the high temperature alternate aging and annealing heat treatment process. The scheme of the invention has technical feasibility, process adaptability, quality reliability, economic rationality and use safety, can effectively make good use of the advantages and disadvantages of the traditional mainstream heat treatment method of austenitic stainless steel, fundamentally solves the unique heat treatment technical problems of poor quality stability, low qualified product rate, low hardness, low mechanical property, poor consistency, poor anti-tarnishing resistance, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like, namely one long step, one high step, four steps, five steps, and the like of the conventional heat treatment of austenitic stainless steel, and is particularly suitable for the heat treatment engineering technical fields of smelting, steel rolling, forging, heat treatment and the like of austenitic stainless steel in steel factories and manufacturing plants.)

1. A method for critical solution and critical start high temperature alternating aging and annealing heat treatment is characterized by comprising the following steps:

a critical solution heat treatment process, the critical solution heat treatment process comprising: firstly, carrying out pre-solid solution critical preheating heating and heat preservation when the austenitic stainless steel is heated to the preheating temperature from room temperature at a medium speed in a heating furnace within a set time, then continuously carrying out pre-solid solution critical stabilizing heating and heat preservation when the austenitic stainless steel is heated to the stabilizing temperature, then continuously carrying out critical solid solution minimum temperature heating and heat preservation when the austenitic stainless steel is heated to the solid solution minimum temperature, then continuously carrying out critical solid solution maximum temperature heating and heat preservation when the austenitic stainless steel is heated to the solid solution maximum temperature, and finally continuously carrying out solid solution cooling when the austenitic stainless steel is cooled to the room temperature by adopting a specific cooling mode;

after the critical solution heat treatment is finished, the critical solution heat treatment process is continued to be started in the high-temperature alternate aging heat treatment process, and the critical solution heat treatment process comprises the following steps: the 1 st critical process is started at high temperature and ended at high temperature alternating aging process: firstly, performing the first half critical starting at high temperature and ending at low temperature without alternating aging process for the first time 1: firstly heating and preserving the austenite stainless steel at the critical aging highest temperature when the temperature of the austenite stainless steel is raised to the aging highest temperature from room temperature at medium speed in a heating furnace within a specified time, then continuously heating and preserving the austenite stainless steel at the critical aging intermediate temperature when the temperature of the austenite stainless steel is rapidly lowered to the aging intermediate temperature, and then continuously heating and preserving the austenite stainless steel at the critical aging lowest temperature when the temperature of the austenite stainless steel is rapidly lowered to the final aging lowest temperature;

then, the first half of the 1 st time is continued to start from the low temperature and end from the high temperature alternating aging process: the method comprises the following steps of continuously heating and preserving heat at the critical aging intermediate temperature when the austenitic stainless steel is rapidly heated from the critical aging minimum temperature to the aging intermediate temperature in a heating furnace within a specified time, and then continuously heating and preserving heat at the critical aging maximum temperature when the austenitic stainless steel is rapidly heated from the critical aging intermediate temperature to the critical aging maximum temperature in the heating furnace within the specified time;

after the 1 st critical starting from the high temperature and ending the high temperature alternating aging process, the 2 nd, 3 rd, … … th and Nth critical alternating aging processes are carried out again: critical alternating aging for the 2 nd time, sequentially and reversely repeating the 1 st half critical starting from the low temperature to the high temperature alternating aging process for 1 time, critical alternating aging for the 3 rd time, sequentially and reversely repeating the 2 nd critical alternating aging process for 1 time, … …, and so on, and sequentially and reversely repeating the N-th critical alternating aging process for 1 time; and (3) continuing the final cooling process after the 2 nd time, the 3 rd time, the … … th time and the Nth time of the critical start at the high temperature and the low temperature or the critical start at the low temperature and the high temperature alternating aging process are ended: the austenitic stainless steel is cooled when the temperature is quickly reduced from the highest temperature or the lowest temperature of the critical aging to the critical annealing temperature by opening a furnace door or other cooling modes along with the furnace;

and finally, continuing the second half critical annealing heat treatment after the first half critical starting from the high-temperature alternating aging heat treatment is finished: the method comprises the steps of performing critical heating and heat preservation on the austenitic stainless steel at the annealing temperature in a heating furnace within a set time, and finally continuing to perform annealing cooling by rapidly cooling the austenitic stainless steel in a specific cooling mode.

2. The method of claim 1, wherein the critical solution heat treatment is performed for a total number of solution times of 1.

3. The method of claim 1, wherein the 4-stage critical solution temperature interval is selected from the group consisting of: and a 4-stage critical solid solution heating temperature range which starts from the stage of raising the temperature from room temperature to the preheating temperature before solid solution Tsccp, continues to raise the temperature to the stabilization temperature before solid solution Tscs, continues to raise the temperature to the solid solution minimum temperature Tcmin, and finally ends at the stage of raising the temperature to the solid solution maximum temperature Tcmax.

4. The method for critical solution and critical start high temperature alternating aging and annealing heat treatment according to claim 1, wherein the mathematical relationship between the critical pre-solution preheating temperature Tscp and the solution minimum theoretical heating temperature Tscmin is as follows: ttscp is Tsctmin- (330-350) DEG C;

wherein Tsscp is the preheating temperature before critical solid solution, and the unit is; tsctmin is the critical solution minimum theoretical heating temperature in degrees Celsius.

5. The method for critical solution and critical start high temperature alternating aging and annealing heat treatment according to claim 1, wherein the mathematical relationship between the critical pre-solution stabilization heating temperature Tscs and the solution minimum theoretical heating temperature Tscmin is as follows: tscs is Tsctmin- (120-150) DEG C;

wherein Tscs is the stabilizing heating temperature before critical solid solution, the unit is the temperature, and is also the heating temperature of the second stage of critical solid solution; tsctmin is the critical solution minimum theoretical heating temperature in degrees Celsius.

6. The method for critical solution and critical start high temperature alternating aging and annealing heat treatment according to claim 1, wherein the mathematical relationship between the critical solution minimum heating temperature Tscmin and the solution minimum theoretical heating temperature Tsctmin and the copper alloy dissolution critical temperature is as follows:

Tsctmin+(5～10)℃≤Tscmin≤1083℃–(13～15)℃

wherein Ttscmin is the critical solid solution minimum heating temperature, and the unit is; tsctmin is the critical solid solution minimum theoretical heating temperature, and the unit is; 1083 ℃ is the copper alloy dissolution critical temperature in units of ℃.

7. The method for critical solution and critical start high temperature alternating aging and annealing heat treatment according to claim 1, characterized in that the mathematical relationship between the critical solution maximum heating temperature Tscmax and the solution maximum theoretical heating temperature Tsctmax and FeS-MnS eutectic solution critical temperature is:

Tscmax≤Tsctmax≤1164℃–(12～14)℃

wherein Tsmax is the critical solid solution maximum heating temperature, the unit is the temperature, and is also the heating temperature of the critical solid solution fourth stage; tstmax is the critical solid solution maximum theoretical heating temperature, and the unit is; the temperature of 1164 ℃ is the dissolution critical temperature of the FeS-MnS eutectic, and the unit is ℃.

8. The method of claim 1, characterized in that the critical solution treatment is divided into 4 stages of heating time: and 4-stage heating time of critical pre-solid solution preheating, critical pre-solid solution stabilizing, critical solid solution lowest temperature and critical solid solution highest temperature corresponding to the critical 4-stage solid solution temperature.

9. Critical solid solubility and critical onset according to claim 1, highThe temperature alternating ageing and annealing heat treatment method is characterized in that the critical solid solution time is carried out according to a decreasing time method, and the heating time tau of each stage of the decreasing time method_scnPreheating heating time tau before solid solution_sc1And decreasing the time step difference τ_sc0The mathematical relationship of (a) is: tau is_scn＝[τ_sc1–(n–1)τ_sc0]；

Wherein, tau_scnHeating time, min or h, tau, at each stage of the critical solid solution decreasing time method_scnIs divided into tau_sc1、τ_sc2、τ_sc3、τ_sc4，τ_sc1＞τ_sc2＞τ_sc3＞τ_sc4；τ_sc1Preheating heating time before solid solution in a critical solid solution first stage, wherein the preheating heating time is min or h; tau is_sc2Stabilizing and heating time before solid solution in a second stage of critical solid solution for min or h; tau is_sc3Heating time is the critical solid solution minimum temperature of the critical solid solution third stage, and min or h; tau is_sc4Heating time of maximum solution temperature in the fourth stage of critical solution treatment, min or h, tau_sc4Less than or equal to 5 min; n is the number of the nth stage of the critical solution heating, and n is 1, 2, 3, 4; tau is_sc0The decreasing time step difference of the critical solid solution heating, min or h, is the same and unchanging specific numerical value.

10. The method of claim 1, characterized in that the critical solution heat treatment process comprises:

the first stage is as follows: austenitic stainless steel is placed in a furnace for a process-defined time τ_sc1Heating from room temperature to a critical preheating temperature Tsccp at a medium speed, and performing critical preheating heating and heat preservation before solid solution;

and a second stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc2Rapidly heating from the critical preheating temperature Tspc to the critical stabilizing temperature Tscs for critical stabilizing heating and heat preservation before solid solution;

and a third stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc3Rapidly heating from the critical stabilization temperature Tscs to the critical solid solution minimum temperature Tcmin to carry out critical solid solution minimum temperature heating and heat preservation;

a fourth stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc4Rapidly heating from the critical solid solution minimum temperature Tcmc to the critical solid solution maximum temperature Tcmax, and heating and preserving the critical solid solution maximum temperature;

and finally, continuously and quickly discharging the austenitic stainless steel from the furnace from the critical solid solution highest temperature Tcmc ax, and quickly cooling the austenitic stainless steel in cooling medium room-temperature water.

Technical Field

The invention relates to the technical field of material heat treatment, in particular to a method for performing alternating aging and annealing heat treatment on critical solid solution and critical starting high temperature.

Background

The heat treatment principle of austenitic stainless steel is quite different from that of alloy structural steel: the alloy structural steel can generate high-temperature austenite structure transformation (good heat treatment manufacturability) under the high-temperature condition, so that the alloy structural steel is very easy to greatly improve the hardness (or mechanical property) by quenching and tempering heat treatment methods; however, austenitic stainless steel cannot generate high-temperature austenitic structure transformation (only limited dissolution and precipitation of alloy element strengthening phases, and poor heat treatment manufacturability) under high-temperature conditions, so that the austenitic stainless steel is extremely difficult to greatly improve the hardness (or mechanical property) through heat treatment methods such as solid solution, aging, annealing and the like.

The meaning of solution heat treatment is: the heat treatment process comprises the following steps of heating austenitic stainless steel to a certain temperature, keeping the temperature, fully dissolving excess phases, and then rapidly cooling to obtain a supersaturated solid solution, wherein the heat treatment process mainly has the main functions of obtaining a supersaturated strengthened solid solution, preparing a structure for precipitation hardening treatment, eliminating stress and carrying out work hardening between forming procedures; the meaning of the aging heat treatment is: after the austenitic stainless steel is subjected to solution treatment, keeping at room temperature or a temperature higher than room temperature to form a solute atom segregation area in a supersaturated solid solution and/or separate out a second phase particle, a dispersed and distributed excess phase and separate out the second phase particle, wherein the main effect is to precipitate and harden the austenitic stainless steel; the meaning of the annealing heat treatment is: the heat treatment process comprises the steps of heating the austenitic stainless steel to a proper temperature before, during or after the solid solution or aging treatment process of the austenitic stainless steel, keeping the temperature at a certain temperature, and then slowly cooling, wherein the heat treatment process mainly has the function of removing residual cold and hot processing stress of the austenitic stainless steel.

The austenitic stainless steel has a main strengthening phase of carbide of alloying elements and a weakening phase of intermetallic compounds (such as Fe)₂W、Fe₂Mo, CuO, FeS, FeO, MnS, etc.); solution and aging and annealing heat treatment methodEven if the strengthening phase and the weakening phase of the same material are different in type, quantity, size, shape, distribution, melting point, brittleness, hardness and the like, the more the austenitic stainless steel alloy elements are, the larger the difference is.

The carbide formed by nickel, chromium, tungsten, molybdenum, vanadium, titanium, aluminum, niobium and other alloy elements has the relative stability in austenitic stainless steel from high to low in the sequence: hf > Zr > Ti > Ta > Nb > V > W > Mo > Cr > Mn > Fe > Co > Ni, so that dissolution of the above-mentioned alloy elements in austenitic stainless steel results in limited dissolution (Fe, Cr)₃C、(Fe，Cr)₇C₃、(W，Mo)₆C and (Fe, Cr, Ni, Mn, W, Mo)₂₃C₆Isoalloyed cementite and fully miscible Mn₃C、Fe₃C、(Fe，Mn)₃C、VC、Ta、NbC、(V，Ta，Nb)C、Mo₂C、W₂C、Fe₃W₃C、Fe₃Mo₃C、Fe₃(W，Mo)₃C, and the like; when the solid solution temperature is more than or equal to 1000 ℃ and more than or equal to 1050 ℃, most carbide phases are respectively basically dissolved and completely dissolved (the aging process is correspondingly influenced); because the solution heating temperature of the existing traditional mainstream austenitic stainless steel is the highest theoretical solution temperature, the unfavorable critical temperature intervals of 700 ℃ -815 ℃ (sensitized intercrystalline corrosion critical temperature region), 940 ℃ (FeS-FeO eutectic melting point and dissolution genetic critical temperature region), 985 ℃ (Fe-FeS eutectic melting point and dissolution genetic critical temperature region), 1083 ℃ (weakened phase copper alloy dissolution critical temperature region), 1164 ℃ (FeS-MnS eutectic melting point and dissolution genetic critical temperature region) and the like can not be quickly avoided, so that the solid solution capacity, range, quality, efficiency and the like of the carbide strengthened phase can not be effectively improved. In fact, the austenitic stainless steel solid solution temperature is not a simple and unchangeable single-point temperature value, but a complex and changeable multi-point temperature range; the existing traditional mainstream solution heat treatment method has the advantages that: the solid solution capability, the range, the quality, the efficiency and the like of one or a few alloy elements in the austenitic stainless steel can be effectively improved; the existing traditional mainstream solution heat treatment method has the following defects: can not effectively improve the solid solution capability, range and quality of most alloy element strengthening phasesThe amount, efficiency, etc. are very small even if the solution time is increased (when the time reaches a certain level, the solution capacity, range, quality, efficiency, etc. of one or a few alloying element solution strengthening phases reach a limit saturation state), and the alloying element strengthening phases can only reach the limit solution capacity, range, quality, efficiency, etc. Therefore, the existing traditional mainstream austenitic stainless steel solution heat treatment method is a one-stage single-point fixed limited solution heat treatment method under the condition that the heating temperature and the heating time are the only conditions, and is a heat treatment method which is considered as a whole under the condition of being not on the whole under the approximate condition.

The aging heat treatment temperature of the austenitic stainless steel is different due to different use requirements such as anti-rust corrosion capability, high-temperature strength, hardness, mechanical property and the like: if the temperature is lower than 500 ℃, the trace amount of needle-shaped carbide with larger grain size is mainly precipitated, and if the temperature is between 550 and 740 ℃, the carbide (Fe, Cr, Ni, Mn, W, Mo) is mainly precipitated₂₃C₆Carbide of the same composite alloy is mainly precipitated (Fe, Cr, Ni, Mn, W, Mo) at 625-670 deg.C₂₃C₆The carbide of the compound alloy is uniformly distributed in the crystal, the carbide begins to grow sharply at the temperature of about 700 ℃, and is mainly precipitated at the temperature of about 800 ℃ (Fe, Cr, Ni, Mn, W, Mo)₇C₆When the temperature of the composite alloy carbide is about 880 ℃, a small amount of (Fe, Cr, Ni, Mn, W, Mo) C composite alloy carbide is mainly precipitated, and when the temperature is higher than 900 ℃, the precipitation amount of the precipitated lamellar carbide is increased to influence the metal hardness and the mechanical property; because the aging heating temperature of the traditional mainstream austenitic stainless steel is the highest aging theoretical temperature, the capability, range, quality, efficiency and the like of precipitating carbide strengthening phases by aging cannot be effectively improved. In fact, the aging temperature of austenitic stainless steel is not a simple and unchangeable single-point temperature value, but a complex and changeable multi-point temperature range; the existing traditional mainstream aging heat treatment method has the advantages that: the aging precipitation capacity, range, quality, efficiency and the like of one or a few alloy element strengthening phases in the austenitic stainless steel can be effectively improved; the prior aging heat treatment method has the following defects: cannot effectively improve the aging precipitation of most alloy element strengthening phasesThe capability, range, quality and efficiency, etc. are very little even if the aging time is increased (after the time reaches a certain degree, the aging capability, range, quality and efficiency, etc. of the one or a few alloying element strengthening phases reach a limit saturation state), and the alloying element strengthening phases can only reach the limited aging precipitation capability, range, quality and efficiency, etc. Therefore, the existing traditional mainstream austenitic stainless steel aging heat treatment method is a one-stage single-point fixed limited aging heat treatment method under the condition that the heating temperature and the heating time are the only conditions, and is a heat treatment method which is considered as a whole under the condition of being not in a comprehensive mode.

The existing traditional mainstream austenitic stainless steel annealing heat treatment methods are divided into a high-temperature annealing method, a medium-temperature annealing method and a low-temperature annealing method. The existing high-temperature annealing method has the advantages that: the effect of removing the residual cold and hot processing stress is good; the existing high-temperature annealing method has the following defects: the austenitic stainless steel has large deformation amount, long heating time, newly generated negative effects of solid solution and aging (particularly influencing the type, the number, the size, the shape, the distribution, the melting point, the brittleness, the hardness and the like of strengthening phases after the solid solution of the austenitic stainless steel), and the difficult problems that an independent process is required to be arranged and the process is not suitable as a final process (only suitable as an intermediate process before the aging after the solid solution, or suitable as a process without the solid solution and aging heat treatment), and the like; the prior moderate temperature annealing method has the advantages that: the effect of removing the residual cold and hot processing stress is good; the existing moderate temperature annealing method has the following defects: the austenitic stainless steel has large deformation amount, long heating time, newly generated aging negative effects (particularly influencing the strengthening phase types, the number, the size, the shape, the distribution, the melting point, the brittleness, the hardness and the like after the solid solution and the aging of the austenitic stainless steel) and the problems that an independent process is required to be arranged and is not suitable to be used as a final process (only suitable to be used as an intermediate process before the aging after the solid solution and suitable to be used as an independent process without the solid solution and the aging heat treatment) and the like cannot be solved; the existing low-temperature annealing method has the advantages that: the austenitic stainless steel has extremely small deformation amount, does not newly generate the negative effects of solid solution or aging (particularly does not influence the type, the quantity, the size, the shape, the distribution, the melting point, the brittleness, the hardness and the like of strengthening phases after the solid solution and the aging of the austenitic stainless steel) and is also suitable for any intermediate process and final process; the existing low-temperature annealing method has the following defects: the effect of removing the residual cold and hot processing stress is not as good as that of a high-temperature annealing method and a medium-temperature annealing method, and the problems of independent working procedures, long heating time and the like cannot be solved.

Although austenitic stainless steel belongs to the stainless steel material series, the phenomenon of 'discoloring and rusting a metal surface' is generated to different degrees by 'bright silvery white metal surface' after machining and staying for a certain time, and the main reasons for the generation are considered to be from the conventional mainstream known viewpoints: the chemical components of austenitic stainless steel do not meet the standard of procurement materials; secondly, the content of Cr, Ni, W and other anti-corrosion metals in the austenitic stainless steel is relatively low or the content of C, P, As, Sb, Bi and other metal elements which are easy to discolor and corrode is relatively high; thirdly, the surface of the austenitic stainless steel is discolored or corroded (generally referred to as corrosion) due to chemical reaction or electrochemical reaction between metal on the surface of the austenitic stainless steel and substances such as oxygen, water, acid, alkali, salt and the like in the atmosphere, wherein the original steel surface is a layer of firm, fine and extremely thin silver white light bright chromium-rich oxide film substance which is destroyed to form loose heterogeneous substances; fourthly, the surface roughness of the austenitic stainless steel is caused; fifthly, the austenitic stainless steel part is caused by working at the temperature of 300-800 ℃. In fact, besides the discolored rusting of austenitic stainless steels, it is also involved in a cause that is not yet recognized to be very important: the method is caused by the improper hot working methods of smelting, steel rolling, forging, heat treatment and the like of the austenitic stainless steel in steel mills and manufacturing plants, particularly the comprehensive action of a plurality of hot working complex factors such as material, chemical components, furnace batch, hot working temperature, time, cooling medium and the like to generate more alloy carbides and non-carbides which are easy to discolor and rust, and the like, and the method is one of the most fundamental reasons which directly influence the final effect of the heat treatment of the austenitic stainless steel.

Based on the comprehensive influence of a plurality of complex factors, the conventional austenitic stainless steel heat treatment technology is difficult to solve the following special heat treatment technical theory and practice problems of 'one long, one high, four different and five low':

firstly, the heat treatment quality stability is poor, the qualified product rate is low: when the heat treatment quality stability is good, the primary heat treatment qualified product rate can only reach 99 percent (especially, the hardness value and the mechanical property can only reach the lower limit value even if the primary heat treatment qualified product rate is qualified); when the heat treatment quality stability is poor, the primary heat treatment yield is highly likely to fail by 100%.

Secondly, the hardness (or mechanical property) of the heat treatment is low and the consistency is poor: the solid solution and aging heat treatment can reach the medium and low hardness value of 20.0-26.5 HRC, the medium and high hardness value of 27.0-28.0 HRC, the high hardness value of 28.5-32.0 HRC, and even the paradoxical phenomenon of qualified Brinell hardness and unqualified Rockwell hardness.

Thirdly, the tarnish resistance is poor: the austenitic stainless steel has strong sensitivity and high speed for changing 'bright silvery white' into 'color change rust' after the metal surface is machined and stays for a certain time.

Fourthly, the heating time of the heat treatment is long, and the efficiency is low: the heating time under the highest temperature conditions of solid solution and aging is long, and the requirement of quick batch production is difficult to realize; in order to remove residual cold and hot processing stress generated before, during and after the solid solution and aging process, an independent annealing process with longer heating time is required; in order to solve the problems of unqualified solid solution and aging heat treatment, rework and repair are forced to be carried out.

Fifthly, the heating reliability of the heat treatment equipment is poor: the existing box-type resistance furnace equipment has poor heating reliability (only has the functions of conduction and radiation heat transfer), and is far inferior to equipment such as a fluidized bed furnace, a salt bath furnace, a vacuum furnace and the like (simultaneously has the functions of conduction, radiation and convection heat transfer) in heating reliability.

Sixthly, the service life of the high-temperature component of the heat treatment equipment is short: the service life of the high-temperature components of the equipment is low due to large high-temperature load and long retention time under the conditions of highest temperature of solid solution and aging.

Seventhly, the heat treatment cost is high: the combination of the above disadvantages ultimately results in high heat treatment costs.

In summary, the conventional mainstream austenitic stainless steel heat treatment methods cannot solve the problems of poor heat treatment quality stability, low qualified product rate, low hardness (or low mechanical property) and poor consistency, poor anti-tarnishing resistance, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like of 'one long, one high, four low, five low' of the specific heat treatment technology theory and practice of austenitic stainless steel.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for high-temperature alternate aging and annealing heat treatment of critical solid solution and critical starting materials. Solves the special heat treatment technical problems of poor quality stability, low qualified product rate, low hardness, low mechanical property, poor consistency, poor anti-tarnishing capability, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like in the prior heat treatment of austenitic stainless steel.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a method of critical solution and critical onset high temperature alternating aging and annealing heat treatment comprising:

a critical solution heat treatment process, the critical solution heat treatment process comprising: firstly, carrying out pre-solid solution critical preheating heating and heat preservation when the austenitic stainless steel is heated to the preheating temperature from room temperature at a medium speed in a heating furnace within a set time, then continuously carrying out pre-solid solution critical stabilizing heating and heat preservation when the austenitic stainless steel is heated to the stabilizing temperature, then continuously carrying out critical solid solution minimum temperature heating and heat preservation when the austenitic stainless steel is heated to the solid solution minimum temperature, then continuously carrying out critical solid solution maximum temperature heating and heat preservation when the austenitic stainless steel is heated to the solid solution maximum temperature, and finally continuously carrying out solid solution cooling when the austenitic stainless steel is cooled to the room temperature by adopting a specific cooling mode;

after the critical solution heat treatment is finished, the critical solution heat treatment process is continued to be started in the high-temperature alternate aging heat treatment process, and the critical solution heat treatment process comprises the following steps: the 1 st critical process is started at high temperature and ended at high temperature alternating aging process: firstly, performing the first half critical starting at high temperature and ending at low temperature without alternating aging process for the first time 1: firstly heating and preserving the austenite stainless steel at the critical aging highest temperature when the temperature of the austenite stainless steel is raised to the aging highest temperature from room temperature at medium speed in a heating furnace within a specified time, then continuously heating and preserving the austenite stainless steel at the critical aging intermediate temperature when the temperature of the austenite stainless steel is rapidly lowered to the aging intermediate temperature, and then continuously heating and preserving the austenite stainless steel at the critical aging lowest temperature when the temperature of the austenite stainless steel is rapidly lowered to the final aging lowest temperature;

then, the first half of the 1 st time is continued to start from the low temperature and end from the high temperature alternating aging process: the method comprises the following steps of continuously heating and preserving heat at the critical aging intermediate temperature when the austenitic stainless steel is rapidly heated from the critical aging minimum temperature to the aging intermediate temperature in a heating furnace within a specified time, and then continuously heating and preserving heat at the critical aging maximum temperature when the austenitic stainless steel is rapidly heated from the critical aging intermediate temperature to the critical aging maximum temperature in the heating furnace within the specified time;

after the 1 st critical starting from the high temperature and ending the high temperature alternating aging process, the 2 nd, 3 rd, … … th and Nth critical alternating aging processes are carried out again: critical alternating aging for the 2 nd time, sequentially and reversely repeating the 1 st half critical starting from the low temperature to the high temperature alternating aging process for 1 time, critical alternating aging for the 3 rd time, sequentially and reversely repeating the 2 nd critical alternating aging process for 1 time, … …, and so on, and sequentially and reversely repeating the N-th critical alternating aging process for 1 time; and (3) continuing the final cooling process after the 2 nd time, the 3 rd time, the … … th time and the Nth time of the critical start at the high temperature and the low temperature or the critical start at the low temperature and the high temperature alternating aging process are ended: opening a furnace door or other cooling modes are adopted to rapidly cool the austenitic stainless steel along with the furnace from the critical aging highest temperature or the lowest temperature to the critical annealing temperature, and the critical temperature is started in the high-temperature alternating aging heat treatment process;

and finally, continuing the second half critical annealing heat treatment after the first half critical treatment is started at the end of the high-temperature alternating aging heat treatment, and depending on the critical annealing heat treatment process: the method comprises the steps of performing critical heating and heat preservation on the austenitic stainless steel at the annealing temperature in a heating furnace within a set time, and finally continuing to perform annealing cooling by rapidly cooling the austenitic stainless steel in a specific cooling mode.

Alternatively, the total number of solid solutions of the critical solid solution heat treatment is 1.

Optionally, the 4-stage critical solid solution temperature interval refers to: and a 4-stage critical solid solution heating temperature range which starts from the stage of raising the temperature from room temperature to the preheating temperature before solid solution Tsccp, continues to raise the temperature to the stabilization temperature before solid solution Tscs, continues to raise the temperature to the solid solution minimum temperature Tcmin, and finally ends at the stage of raising the temperature to the solid solution maximum temperature Tcmax.

Optionally, the mathematical relationship between the critical pre-solid solution preheating temperature Tscp and the solid solution minimum theoretical heating temperature Tscmin is as follows: ttscp is Tsctmin- (330-350) DEG C;

wherein Tsscp is the preheating temperature before critical solid solution, and the unit is; tsctmin is the critical solution minimum theoretical heating temperature in degrees Celsius.

Optionally, the mathematical relationship between the critical pre-solid solution stabilization heating temperature Tscs and the solid solution minimum theoretical heating temperature Tscmin is as follows: tscs is Tsctmin- (120-150) DEG C;

wherein Tscs is the stabilizing heating temperature before critical solid solution, the unit is the temperature, and is also the heating temperature of the second stage of critical solid solution; tsctmin is the critical solution minimum theoretical heating temperature in degrees Celsius.

Optionally, the mathematical relationship between the critical solid solution minimum heating temperature Tscmin and the solid solution minimum theoretical heating temperature Tsctmin and the copper alloy dissolution critical temperature is as follows:

Tsctmin+(5～10)℃≤Tscmin≤1083℃–(13～15)℃

wherein Ttscmin is the critical solid solution minimum heating temperature, and the unit is; tsctmin is the critical solid solution minimum theoretical heating temperature, and the unit is; 1083 ℃ is the copper alloy dissolution critical temperature in units of ℃.

Optionally, the mathematical relation between the critical solid solution maximum heating temperature Tscmax and the solid solution maximum theoretical heating temperature Tsctmax and the FeS-MnS eutectic dissolution critical temperature is as follows:

Tscmax≤Tsctmax≤1164℃–(12～14)℃

wherein Tsmax is the critical solid solution maximum heating temperature, the unit is the temperature, and is also the heating temperature of the critical solid solution fourth stage; tstmax is the critical solid solution maximum theoretical heating temperature, and the unit is; the temperature of 1164 ℃ is the dissolution critical temperature of the FeS-MnS eutectic, and the unit is ℃.

Optionally, the critical solid solution is divided into 4 stages of heating time: and 4-stage heating time of critical pre-solid solution preheating, critical pre-solid solution stabilizing, critical solid solution lowest temperature and critical solid solution highest temperature corresponding to the critical 4-stage solid solution temperature.

Optionally, the critical solid solution time is performed according to a decreasing time method, and the heating time τ is at each stage of the decreasing time method_scnPreheating heating time tau before solid solution_sc1And decreasing the time step difference τ_sc0The mathematical relationship of (a) is: tau is_scn＝[τ_sc1–(n–1)τ_sc0]；

Wherein, tau_scnHeating time, min or h, tau, at each stage of the critical solid solution decreasing time method_scnIs divided into tau_sc1、τ_sc2、τ_sc3、τ_sc4，τ_sc1＞τ_sc2＞τ_sc3＞τ_sc4；τ_sc1Preheating heating time before solid solution in a critical solid solution first stage, wherein the preheating heating time is min or h; tau is_sc2Stabilizing and heating time before solid solution in a second stage of critical solid solution for min or h; tau is_sc3Heating time is the critical solid solution minimum temperature of the critical solid solution third stage, and min or h; tau is_sc4Heating time of maximum solution temperature in the fourth stage of critical solution treatment, min or h, tau_sc4Less than or equal to 5 min; n is the number of the nth stage of the critical solution heating, and n is 1, 2, 3, 4; tau is_sc0The decreasing time step difference of the critical solid solution heating, min or h, is the same and unchanging specific numerical value.

Optionally, the critical solution heat treatment process comprises:

the first stage is as follows: rendering austenite toThe steel is heated in a furnace for a defined time τ_sc1Heating from room temperature to a critical preheating temperature Tsccp at a medium speed, and performing critical preheating heating and heat preservation before solid solution;

and a second stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc2Rapidly heating from the critical preheating temperature Tspc to the critical stabilizing temperature Tscs for critical stabilizing heating and heat preservation before solid solution;

and a third stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc3Rapidly heating from the critical stabilization temperature Tscs to the critical solid solution minimum temperature Tcmin to carry out critical solid solution minimum temperature heating and heat preservation;

a fourth stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc4Rapidly heating from the critical solid solution minimum temperature Tcmc to the critical solid solution maximum temperature Tcmax, and heating and preserving the critical solid solution maximum temperature;

and finally, continuously and quickly discharging the austenitic stainless steel from the furnace from the critical solid solution highest temperature Tcmc ax, and quickly cooling the austenitic stainless steel in cooling medium room-temperature water.

The scheme of the invention at least comprises the following beneficial effects:

(1) the method for heat treatment of the austenitic stainless steel by the high-temperature alternating aging and annealing, which starts from the critical solid solution and critical solution, has the advantages of technical feasibility, process adaptability, quality reliability, economic rationality and use safety, effectively draws the advantages and disadvantages of the traditional mainstream austenitic stainless steel heat treatment method, and fundamentally solves the problems of poor quality stability, low qualified product rate, low hardness (or low mechanical property) and consistency, poor anti-tarnishing resistance, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components and high cost of the conventional one-long-one-high-four-difference five-low heat treatment technology and practice of the austenitic stainless steel.

(2) The method for the high-temperature alternating aging and annealing heat treatment of the critical solid solution and critical phase has good heat treatment manufacturability, can effectively increase the solid solution and aging strengthening phase, reduce or inhibit the solid solution and aging weakening phase and reduce the residual cold and hot processing stress and deformation, and can meet the service performance requirements of austenitic stainless steel.

(3) The method for the critical solid solution and critical high-temperature alternating aging and annealing heat treatment has the advantages of good quality stability and high reliability, can accurately, effectively and quickly obtain the optimized heat treatment hardness (or mechanical property) with the distribution range of the middle limit or the upper limit and the tolerance of less than or equal to 2.5HRC, and can ensure that the qualified rate of the hardness (or mechanical property) of the one-time heat treatment reaches 100 percent.

(4) The critical solid solution and critical temperature of the invention are high temperature alternating aging and annealing heat treatment method, which can effectively improve the surface tarnish resistance of the austenitic stainless steel after machining.

(5) The critical solid solution and critical temperature of the invention starts from the high-temperature alternating aging and annealing heat treatment method, which can effectively improve the heat treatment efficiency (especially can be used for full-load furnace charging and rapid production, and can reduce the total time of solid solution, aging and annealing heat treatment by at least 40 percent, etc.).

(6) The critical solid solution and critical temperature of the invention starts from the high temperature alternating aging and annealing heat treatment method, which can effectively improve the service life of the high temperature components of the heating equipment.

(7) The method for the heat treatment of the austenitic stainless steel starts from the high-temperature alternating aging and annealing treatment method for critical solid solution and critical solution, and can effectively reduce the heat treatment cost of the austenitic stainless steel.

Drawings

FIG. 1 is a schematic diagram of the prior austenitic stainless steel showing the solution, aging and annealing heat treatment processes (including the heating, heat preservation, cooling processes, time used and the like of the solution, aging and annealing heat treatment) consisting of 1 time 1-stage solution treatment under the condition of the highest solution temperature, 1 time 1-stage aging under the condition of the highest aging temperature and 1 time 1-stage annealing under the condition of medium-temperature annealing or low-temperature annealing temperature;

FIG. 2 is a schematic flow chart of the critical solution and critical onset high temperature alternate aging and annealing heat treatment process of the present invention;

FIG. 3 is a schematic diagram of the austenitic stainless steel consisting of 1 time of 4-stage critical solution treatment under the condition of critical solution temperature by a descending time method, 1 time of 3 times under the condition of critical aging temperature by an equal time method (wherein, the 1 st time of 4-stage temperature reduction without alternation, the 2 nd time of 4-stage temperature rise alternation, the 3 rd time of 4-stage temperature reduction alternation) critical solution treatment and critical solution treatment starting from the high-temperature alternating aging and annealing heat treatment process (including temperature rise, heat preservation, temperature reduction, cooling process and time used for critical solution treatment, critical aging and critical annealing heat treatment) under the condition of critical low-temperature annealing temperature by 1 time of 1 time.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

As shown in fig. 2, an embodiment of the present invention provides a method for critical solution and critical start high temperature alternating aging and annealing heat treatment, comprising: step 21, critical solution heat treatment process; and step 22, starting from the high-temperature alternating aging and annealing heat treatment process.

The method comprises the following steps: firstly, carrying out a first part of critical solution heat treatment, and finally carrying out a second part of critical composite heat treatment starting from high-temperature alternating aging and critical annealing.

The first part of the critical solution heat treatment process: the critical solution heat treatment process comprises the steps of critical solution heat treatment process comprising critical preheating heating and heat preservation before solid solution when the temperature of austenitic stainless steel is raised from room temperature to the preheating temperature at a medium speed in a heating furnace within a specified time, critical stabilizing heating and heat preservation before solid solution when the temperature of austenitic stainless steel is raised to the stabilizing temperature, critical solution lowest temperature heating and heat preservation when the temperature of austenitic stainless steel is raised to the solution lowest temperature, critical solution highest temperature heating and heat preservation when the temperature of austenitic stainless steel is raised to the solution highest temperature, solid solution cooling when the temperature of austenitic stainless steel is lowered to the room temperature by a special cooling mode, and the like;

the second part of critical treatment begins in a high-temperature alternating ageing heat treatment process: after the first part of critical solution heat treatment is finished, continuing to perform a second part of critical high-temperature alternate aging heat treatment, wherein the 1 st critical high-temperature alternate aging heat treatment process comprises the following steps: firstly, performing the first half critical starting at high temperature and ending at low temperature without alternating aging process for the first time 1: firstly heating and preserving the austenite stainless steel at the critical aging highest temperature when the austenite stainless steel is heated to the aging highest temperature from room temperature at medium speed in a heating furnace within a specified time, then continuously heating and preserving the austenite stainless steel at the critical aging intermediate temperature when the austenite stainless steel is rapidly cooled to the aging intermediate temperature, and then continuously heating and preserving the austenite stainless steel at the critical aging lowest temperature when the austenite stainless steel is rapidly cooled to the final aging lowest temperature; then, the first half of the 1 st time is continued to start from the low temperature and end from the high temperature alternating aging process: namely, the austenitic stainless steel is continuously heated and kept warm at the critical aging middle temperature when the temperature is rapidly raised from the critical aging lowest temperature to the aging middle temperature in the heating furnace within the specified time, and then the austenitic stainless steel is continuously heated and kept warm at the critical aging highest temperature when the temperature is rapidly raised from the critical aging middle temperature to the critical aging highest temperature in the heating furnace within the specified time (the 1 st time of critical start is high temperature and the high temperature alternating aging process is all ended);

after the 1 st critical starting from the high temperature and ending the high temperature alternating aging process, the 2 nd, 3 rd, … … th and Nth critical alternating aging processes are carried out again: critical alternating aging for 2 times, sequentially and reversely repeating the first half part of critical starting from low temperature and ending at high temperature alternating aging for 1 time (the critical starting from high temperature and ending at low temperature alternating aging for 2 times), or critical alternating aging for 3 times, sequentially and reversely repeating the critical alternating aging for 2 times (the critical starting from low temperature and ending at high temperature alternating aging for 3 times), … …, and so on, and critical alternating aging for N times, sequentially and reversely repeating the critical alternating aging for 1 time (the critical starting from high temperature and ending at low temperature or the critical starting from low temperature and ending at high temperature alternating aging for N times);

and (3) after the 2 nd, 3 rd, … … th or Nth critical start from high temperature to low temperature or the critical start from low temperature to high temperature, the end of the alternating aging process, continuing the final cooling process: opening a furnace door or other cooling modes are adopted to rapidly cool the austenitic stainless steel along with the furnace from the critical aging highest temperature or the lowest temperature to the critical annealing temperature, and the critical temperature is started in the high-temperature alternating aging heat treatment process (the second part of the critical temperature is started in the high-temperature alternating aging heat treatment process and is completely finished);

and finally, continuing the second half critical annealing heat treatment after the first half critical treatment of the second part is started at the end of the high-temperature alternating aging heat treatment, and depending on the critical annealing heat treatment process: the method comprises the critical annealing heat treatment process which comprises the steps of critical heating and heat preservation of the austenitic stainless steel at the annealing temperature in a heating furnace within a specified time, annealing cooling of the austenitic stainless steel by rapid cooling in a specific cooling mode and the like.

In an embodiment of the present invention, the first partial critical solution heat treatment method is a 4-stage critical solution heat treatment method performed under conditions such as a 4-stage heating temperature range, a 4-stage heating sequence, a 4-stage heating time, a 4-stage heating frequency, a specific cooling method, and the like.

In an embodiment of the present invention, the total number of solid solutions of the first part of the critical solid solution heat treatment is 1.

In an embodiment of the present invention, the first part critical solid solution heating temperature interval refers to: and a 4-stage critical solid solution heating temperature interval which starts from the stage of raising the temperature from room temperature to the pre-critical solid solution preheating temperature Tsccp, continues to raise the temperature to the critical pre-solid solution stabilizing temperature Tscs, continues to raise the temperature to the critical solid solution lowest temperature Tcmin, and finally ends at the stage of raising the temperature to the critical solid solution highest temperature Tcmax.

In the embodiment of the invention, the number of the first part solution heating temperature interval stages is moderate: for example, the solid solubility in the 1 stage is too poor, the solid solubility in the 2 stage is good, and the solid solubility in the 6 or more stages is excessive, so in this embodiment, a 4-stage critical solid solubility heating temperature range is set in which the preheating temperature before solid solubility Tscp, the stabilization temperature before solid solubility Tscs, the minimum solid solubility temperature Tscmin, and the maximum solid solubility temperature Tscmax are different: the preheating temperature Tscc interval before solid solution in the critical solid solution first stage is not only the most favorable heating temperature interval for effectively overcoming the defects that the austenitic stainless steel has low thermal conductivity below 700-800 ℃ and serious high-temperature expansion and reduces thermal stress and deformation, but also the most favorable heating temperature interval for quickly avoiding 450-500 ℃ (a chromium-poor precipitation critical temperature area and a large-particle-size needle-rod-shaped carbide precipitation critical temperature area), 475 ℃ (a cold brittleness critical temperature area and a large-particle-size needle-rod-shaped carbide precipitation critical temperature area), 550-670 ℃ (graphitization, intercrystalline corrosion or along a crystal brittleness critical temperature area) and the like in the temperature rise stage; the stabilizing temperature Tscs interval before solid solution of the second stage of critical solid solution is not only used for reducing the deformation and residual stress of the workpiece and facilitating the solid solution of Cr but also used for dissolving Cr without forming Cr₂₃C₆The steel is characterized in that the steel forms a stable TiC or NbC most favorable heating and heat preservation temperature interval by the aid of the strengthening phase (the strengthening phase is not precipitated in the intergranular region and does not lean chromium in the grain boundary), and also quickly avoids 700-815 ℃ (a sensitized intercrystalline corrosion critical temperature region), 940 ℃ (a FeS-FeO eutectic melting point and a dissolution genetic critical temperature region), 985 ℃ (a Fe-FeS eutectic melting point and a dissolution genetic critical temperature region) and a most favorable heating temperature interval close to an effective solid solution minimum temperature Tcmc and the like in a temperature raising stage; the solid solution minimum temperature Tscomin interval of the critical solid solution third stage is not only an effective solid solution minimum temperature interval, but also an effective solid solution minimum temperature interval which is quickly kept away from 940 ℃ (FeS-FeO eutectic melting point and dissolution inheritance critical temperature area), 985 ℃ (Fe-FeS eutectic melting point and dissolution inheritance critical temperature area), 1083 ℃ (weakening phase copper alloy dissolution and inheritance critical temperature area) and 1164 ℃ (FeS-MnS eutectic melting point and dissolution inheritance critical temperature area) in the temperature raising stageBulk melting point and dissolution genetic critical temperature region), and the like; the solid solution highest temperature Tsccax interval of the critical solid solution fourth stage is an effective solid solution highest temperature interval, and is also an optimal heating temperature interval which rapidly avoids 1083 ℃ (a weakened phase copper alloy dissolution and heredity critical temperature area), 1164 ℃ (a FeS-MnS eutectic melting point and dissolution heredity critical temperature area), 1193 ℃ (a FeS compound melting point and a dissolution heredity critical temperature area) and the like in the temperature rising stage. The final results show that: the critical solid solution is set to be in the temperature intervals with different stages 4, so that the potential special function of solid solution can be fully excavated, the solid solution capacity, the quality, the efficiency and the like are greatly improved, and particularly, the solid solution strengthening phase can be greatly increased, the solid solution weakening phase can be reduced or inhibited, the heating stress can be reduced, the high-temperature heating time can be shortened, the anti-tarnishing capacity can be improved, the efficiency can be improved, the service life of high-temperature components of heating equipment can be prolonged, and the like.

In the embodiment of the invention, the mathematical relation between the critical pre-solid solution preheating temperature Tsccp and the solid solution minimum theoretical heating temperature Tcmin is as follows: ttscp is Tsctmin- (330-350) DEG C;

wherein Tsscp is the preheating temperature before critical solid solution, DEG C, and is also the heating temperature of the first stage of critical solid solution; tsctmin is the critical solution minimum theoretical heating temperature, DEG C.

In the embodiment of the invention, the mathematical relation between the critical pre-solid solution stabilizing heating temperature Tscs and the solid solution minimum theoretical heating temperature Tcmin is as follows: tscs is Tsctmin- (120-150) DEG C;

wherein Tscs is the stabilizing heating temperature before critical solid solution, DEG C, and is also the heating temperature of the second stage of critical solid solution; tsctmin is the critical solution minimum theoretical heating temperature, DEG C.

In the embodiment of the invention, the mathematical relation between the critical solid solution minimum heating temperature Tcmin, the solid solution minimum theoretical heating temperature Tsctmin and the copper alloy dissolution critical temperature is as follows:

Tsctmin+(5～10)℃≤Tscmin≤1083℃–(13～15)℃

tscomin is the critical solid solution minimum heating temperature, DEG C, and is the heating temperature of the critical solid solution third stage; tsctmin is the critical solution minimum theoretical heating temperature, DEG C; 1083 ℃ is the copper alloy dissolution critical temperature, DEG C.

In the embodiment of the invention, the mathematical relation between the critical solid solution maximum heating temperature Tcmax and the solid solution maximum theoretical heating temperature Tctmax and the FeS-MnS eutectic dissolution critical temperature is as follows:

Tscmax≤Tsctmax≤1164℃–(12～14)℃

wherein Tsmax is the critical solid solution maximum heating temperature, DEG C, and is also the heating temperature of the fourth stage of the critical solid solution; tstmax is the critical maximum theoretical heating temperature of solid solution, DEG C; the temperature of 1164 ℃ is the dissolution critical temperature of the FeS-MnS eutectic, and the temperature is lower.

In the examples of the present invention, the critical solid solution is divided into 4 stages of heating time: and 4-stage heating time of critical pre-solid solution preheating, critical pre-solid solution stabilizing, critical solid solution lowest temperature and critical solid solution highest temperature corresponding to the critical 4-stage solid solution temperature.

In the embodiment of the invention, the critical solid solution time is carried out according to a decreasing time method, and the heating time tau at each stage of the decreasing time method_scnPreheating heating time tau before solid solution_sc1And decreasing the time step difference τ_sc0The mathematical relationship of (a) is: tau is_scn＝[τ_sc1–(n–1)τ_sc0]；

In the formula tau_scnHeating time, min or h, tau, at each stage of the critical solid solution decreasing time method_scnIs divided into tau_sc1、τ_sc2、τ_sc3、τ_sc4，τ_sc1＞τ_sc2＞τ_sc3＞τ_sc4；τ_sc1Preheating heating time before solid solution in a critical solid solution first stage, wherein the preheating heating time is min or h; tau is_sc2Stabilizing and heating time before solid solution in a second stage of critical solid solution for min or h; tau is_sc3Heating time is the critical solid solution minimum temperature of the critical solid solution third stage, and min or h; tau is_sc4Heating time of maximum solution temperature in the fourth stage of critical solution treatment, min or h, tau_sc4Less than or equal to 5 min; n is the number of the nth stage of the critical solution heating, and n is 1, 2, 3, 4; tau is_sc0Decreasing critical solution heatingThe time step difference, min or h, is the same constant specific value.

In an embodiment of the present invention, the first part critical solution heat treatment final cooling method is: cooled in room temperature water.

In an embodiment of the present invention, the first part of the critical solution heat treatment process is:

the first stage is as follows: austenitic stainless steel is placed in a furnace for a process-defined time τ_sc1Heating from room temperature to a critical preheating temperature Tsccp at a medium speed, and performing critical preheating heating and heat preservation before solid solution;

and a second stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc2Rapidly heating from the critical preheating temperature Tspc to the critical stabilizing temperature Tscs for critical stabilizing heating and heat preservation before solid solution;

and a third stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc3Rapidly heating from the critical stabilization temperature Tscs to the critical solid solution minimum temperature Tcmin to carry out critical solid solution minimum temperature heating and heat preservation;

a fourth stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tau_sc4Rapidly heating from the critical solid solution minimum temperature Tcmc to the critical solid solution maximum temperature Tcmax, and heating and preserving the critical solid solution maximum temperature;

and finally, continuously and quickly discharging the austenitic stainless steel from the furnace from the critical solid solution highest temperature Tcmax, and quickly cooling the austenitic stainless steel in cooling medium room-temperature water (and placing the cooled austenitic stainless steel on a room-temperature working site).

In an embodiment of the present invention, the second part of the critical process starts with the high temperature alternate aging and critical annealing composite heat treatment method: the composite heat treatment method is characterized in that the critical starting high-temperature alternating aging heat treatment is continuously compounded by critical annealing heat treatment which is carried out under the conditions of a first half part of a second part, a first half part, a multi-stage heating temperature interval, a multi-stage heating sequence, a specific cooling mode and the like and is started at high temperature alternating aging heat treatment, and the critical annealing heat treatment which is carried out under the conditions of a second half part, a first stage heating temperature interval, a first stage heating sequence, a first stage heating time, a first stage heating frequency, a specific cooling mode and the like.

In the embodiment of the invention, the total number of the alternate aging times of the second part starting from the high temperature and ending at the low temperature alternate aging heat treatment is 1 time, wherein 1 time comprises 2 ≤ N ≤ 6 times, N ≤ 2, or 3, 4, or 5, 6 times, and finally the alternate aging process is ended with N ═ 2, 4, or 6 times (each alternate aging process should comprise at least 1 cooling and 1 heating at the same time).

In the embodiment of the invention, the total number of the alternate aging times of the second part starting from the high temperature and ending with the high temperature alternate aging heat treatment is 1 time, 1 time comprises 1 or more and less than or equal to 5 times of N, N is 1, or 2, 3, or 4, 5, and finally the alternate aging process is ended with N being 1, 3 or 5 times (each alternate aging process at least comprises 1 time of temperature reduction and 1 time of temperature increase at the same time).

In the embodiment of the invention, the first half of the second part starts in a multi-stage temperature reduction aging temperature interval related to high-temperature alternating aging: the method comprises a 1 st critical multi-stage non-alternating cooling aging temperature interval: starting from a critical multi-stage cooling and aging highest heating temperature interval Tacmax (marked as Tacmax-1), sequentially passing through n-2 critical multi-stage aging intermediate heating temperature intervals Tacm (marked as Tacm-1) and finally ending to a critical multi-stage aging lowest heating temperature interval Tacmin (marked as Tacmin-1), wherein n is more than or equal to 3 and less than or equal to 7, namely n is 3, 4, 5, 6 or 7; critical multi-stage cooling alternating aging temperature interval of 2 nd, 3 rd or 4 th time: the critical multi-stage cooling and aging process is sequentially repeated, and the relation of the numerical values of the critical multi-stage cooling alternating aging lowest temperature interval of the 1 st time, the 2 nd time, the 3 rd time and the 4 th time is as follows: tacmin-1 ═ Tacmin-2 ═ Tacmin-3 ═ Tacmin-4, and the relation of the values of the intermediate heating temperature interval of the 1 st, 2 nd, 3 rd and 4 th critical multi-stage cooling alternating aging is as follows: the relationship formula of the highest temperature interval value of the 1 st, 2 nd, 3 rd and 4 th critical multi-stage cooling alternating ageing is as follows: tacmax-1 ═ Tacmax-2 ═ Tacmax-3 ═ Tacmax-4.

In the embodiment of the present invention, the second part first half is critically started in the multistage temperature-aging temperature zone relating to high-temperature alternate aging: the method comprises a 1 st critical multi-stage non-alternating temperature-rise aging temperature interval: starting from a critical multi-stage heating and aging minimum heating temperature interval Tacmin (marked as Tacmin-1), sequentially passing through n-2 critical multi-stage aging intermediate heating temperature intervals Tacm (marked as Tacm-1) and finally ending to a critical multi-stage aging maximum heating temperature interval Tacmax (marked as Tacmax-1), wherein n is more than or equal to 3 and less than or equal to 7, namely n is 3, 4, 5, 6 or 7; critical multi-stage temperature rise alternating aging temperature interval of 2 nd, 3 rd or 4 th time: the critical temperature-rising aging process is sequentially repeated, and the relation of the numerical values of the critical multi-stage temperature-rising alternating aging lowest temperature interval of the 1 st time, the 2 nd time, the 3 rd time and the 4 th time is as follows: tacmin-1-2-3-4, and the relation of the intermediate heating temperature interval values of the 1 st, 2 nd, 3 rd and 4 th heating time is as follows: the relationship of the maximum temperature interval value of the 1 st, 2 nd, 3 rd and 4 th critical multi-stage temperature rise alternating aging is as follows: tacmax-1 ═ Tacmax-2 ═ Tacmax-3 ═ Tacmax-4.

In the embodiment of the invention, because the ageing temperature range of the austenitic stainless steel is narrow (between 170 ℃ and 230 ℃), the critical starting point is neither too small nor too much in the high-temperature alternating ageing temperature range: the aging temperature range of the 1 stage belongs to the prior art (no temperature difference), and the aging capability is too poor; in the aging temperature range of 2 stages (the temperature difference is large), the aging capability is increased but is still insufficient; when the temperature is within the aging temperature range of not less than 8 stages (the temperature difference is too small), the aging capability is excessive (in fact, a certain aging capability is still provided in each temperature rise or decrease transition stage where the temperature difference is too small). Therefore, setting the critical starting high temperature alternating ageing temperature interval to be 3 ≦ n ≦ 7, i.e. n ≦ 3, 4, 5, 6 or 7 stages may be more beneficial to improve ageing capacity, range, quality and efficiency, etc.

In the embodiment of the invention, the second part of critical starting from the high temperature alternating ageing temperature interval has the following main functions: the critical aging maximum heating temperature Tacmax interval is the maximum temperature interval of effective aging, and is also the critical temperature area which rapidly avoids 850 ℃ -900 ℃ in the cooling and heating stages (forming a sigma phase critical temperature area, and slightly precipitating (Fe, Cr, Ni, Mn, W, Mo) C composite alloy carbide or lamellar carbide); the critical middle aging n-2 staged temperature Tacm intervals are the optimal heating and heat preservation temperature intervals between the critical aging highest heating temperature Tacmax interval and the critical aging lowest heating temperature Tacmin interval; the minimum heating staged temperature Tacmin interval of critical aging is the minimum temperature interval of effective aging, and is also the most beneficial heating and heat preservation temperature interval which rapidly avoids 450 ℃ -500 ℃ (chromium-poor precipitation critical temperature area and large-particle-size needle-rod-shaped carbide precipitation critical temperature area), 475 ℃ (cold brittleness critical temperature area and large-particle-size needle-rod-shaped carbide precipitation critical temperature area), 550 ℃ -670 ℃ (graphitization, intercrystalline corrosion or crystal-brittle fracture critical temperature area) and the like in the cooling and heating stages. Therefore, setting the high-temperature alternating aging temperature interval starting from the critical point to be n staged intervals can more effectively increase the aging strengthening phase, reduce or inhibit the aging weakening phase, obtain the optimized hardness interval range with good quality stability, high reliability and good consistency of heat treatment hardness, improve the anti-tarnishing capacity, improve the heat treatment efficiency and the like.

In the embodiment of the invention, the mathematical relation between the maximum heating temperature Tacmax of the high-temperature alternating ageing and the maximum theoretical heating temperature Tactmax of the ageing is as follows: tacmax is Tactmax- (20-30) DEG C;

wherein Tacmax is the critical temperature starting from the highest heating temperature of high-temperature alternating aging at DEG C; tactmax is the maximum theoretical heating temperature of aging at DEG C.

In the embodiment of the invention, the mathematical relation between the minimum heating temperature Tacmin of high-temperature alternating ageing and the minimum theoretical heating temperature Tactmin of ageing is as follows: tacmin + (20-30) DEG C;

wherein Tacmin is the critical temperature starting from the lowest heating temperature of high-temperature alternating aging at DEG C; tactmin is the lowest theoretical heating temperature of aging at DEG C.

In the embodiment of the invention, the mathematical relation between the intermediate heating temperature Tacm of the first half part of the second part starting from each stage of high-temperature alternating ageing and the ageing minimum heating temperature Tacmin and the ageing maximum heating temperature Tacmax is as follows: tacm ═ Tacmin + n_i(Tacmax–Tacmin)/(n–1)

Wherein Tacm is the intermediate heating temperature and DEG C of each stage of the critical high-temperature alternating aging, and is the specific stage temperature from the 2 nd stage to the 2 nd last stage of the critical cooling or heating alternating aging; tacmin is the minimum heating temperature of critical temperature reduction or temperature rise alternating aging at DEG C; n is_iThe specific nth heating temperature interval from high to low or from low to high for the 2 nd to the 2 nd last phases_iNumber of stages, n being not less than 1_iN is less than or equal to 5_i1, 2, 3, 4 or 5; tacmax is the critical cooling or heating alternating aging maximum heating temperature, DEG C; (Tacmax-Tacmin)/n is a specific value with the temperature difference of critical temperature reduction or temperature rise decreasing or increasing and the temperature difference being unchanged; n is the total number of stages starting from the critical aging minimum temperature Tacmin and ending at the critical aging maximum heating temperature Tacmax or starting from the critical aging maximum heating temperature Tacmax and ending at the critical aging minimum heating temperature Tacmin, n is more than or equal to 3 and less than or equal to 7, namely n is 3, 4, 5, 6 or 7.

In the embodiment of the invention, the mathematical relation between the critical starting high-temperature alternating aging working heating temperature Tacw of the first half part of the second part and the workpiece use temperature Tw, the critical starting high-temperature alternating aging minimum heating temperature Tacmin and the critical starting high-temperature alternating aging maximum heating temperature Tacmax is as follows:

Tacmin＜Tw+(60～100)℃≤Tacw≤Tacmax

wherein Tacw is critical starting from the high-temperature alternating aging working heating temperature, DEG C, and Tacw should appear at least once in each critical middle aging heating temperature Tacm interval; tw is the workpiece use temperature, DEG C; tacmin is the critical temperature starting from the lowest heating temperature of high-temperature alternating aging at DEG C; tacmax is the critical temperature starting from the highest heating temperature of high-temperature alternating aging at DEG C.

In the embodiment of the invention, the first half of the second part is critically started at the total time tau of high-temperature alternating ageing_acNAnd the total time tau of theoretical aging_aNtThe mathematical relationship of (a) is: tau is_acN＝(1/2～1/3)τ_aNt；

In the formula tau_acNThe critical starting time is the total time of high-temperature alternating aging, min or h; tau is_aNtThe theoretical total aging time is min or h.

In the embodiment of the invention, when the critical starting time of the high-temperature alternating ageing time is carried out according to the equal time method, the critical starting time of the equal time method is the total heating time tau of the high-temperature alternating ageing time_acNHeating time tau in each stage corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages_acnThe mathematical relationship of (a) is: tau is_acN＝∑τ_acn＝∑τ_acN/N；

In the formula tau_acNThe critical point of the equal time method is the total time of high-temperature alternating aging heating, min or h; tau is_acnHeating time of each stage corresponding to aging in heating temperature ranges of 1 st stage, 2 nd stage, 3 rd stage, … …, and nth stage of high-temperature alternating aging is set to be tau/min or h/h_ac1、τ_ac2、τ_ac3、τ_ac4、τ_ac5、τ_ac6、τ_ac7，τ_ac1＝τ_ac2＝τ_ac3＝τ_ac4＝τ_ac5＝τ_ac6＝τ_ac7(ii) a N is the number of the total stages starting from the high-temperature alternating aging heating, and is more than or equal to 3 and less than or equal to 7 (namely N is 3, 4, 5, 6 or 7); n is the number of the nth stage starting from the high-temperature alternating ageing heating, and n is more than or equal to 1 and less than or equal to 7 (namely n is 1, 2, 3, 4, 5, 6 or 7).

In the embodiment of the invention, when the critical starting time of the high-temperature alternating ageing time is carried out according to the increasing time method, the critical starting time of the increasing time method is the total heating time tau of the high-temperature alternating ageing time_acNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heating_acnThe mathematical relationship of (a) is: tau is_acN＝∑τ_acn＝∑[τ_ac1+(n–1)τ_ac0]；

In the formula tau_acNThe critical point of the increasing time method is the total time of high-temperature alternating aging heating, min or h; n is the number of the total stages starting from the high-temperature alternating aging heating, and is more than or equal to 3 and less than or equal to 7 (namely N is 3, 4, 5, 6 or 7); tau is_acnHeating time of each stage of high-temperature alternating ageing is critical, min/time or h/time is respectively tau_ac1、τ_ac2、τ_ac3、τ_ac4、τ_ac5、τ_ac6Or τ_ac7，τ_ac1＞τ_ac2＞τ_ac3＞τ_ac4＞τ_ac5＞τ_ac6Or > tau_ac7(ii) a n is the number of the nth stage starting from the high-temperature alternating ageing heating, and n is more than or equal to 1 and less than or equal to 7 (namely n is 1, 2, 3, 4, 5, 6 or 7); tau is_ac1Heating time is in a first stage of high-temperature alternating ageing for min/time or h/time; tau is_ac0The critical point is that the heating time of the high-temperature alternating aging increases the grade difference, min/time or h/time, and is the same and unchangeable specific numerical value.

In the embodiment of the invention, when the critical starting from the high-temperature alternating ageing time is carried out according to a decreasing time method, the critical starting from the high-temperature alternating ageing heating total time tau of the decreasing time method_acNHeating time tau in each stage corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages_acnThe mathematical relationship of (a) is: tau is_acN＝∑τ_acn＝∑[τ_ac1–(n–1)τ_ac0]；

In the formula tau_scNThe criticality of the decreasing time method is started from the total time of high-temperature alternating aging heating for min/time or h/time; n is the number of the total stages starting from the high-temperature alternating aging heating, and is more than or equal to 3 and less than or equal to 7 (namely N is 3, 4, 5, 6 or 7); tau is_acnHeating time of each stage corresponding to aging in heating temperature ranges of 1 st stage, 2 nd stage, 3 rd stage, … …, and nth stage of high-temperature alternating aging is set to be tau/min or h/h_ac1、τ_ac2、τ_ac3、τ_ac4、τ_ac5、τ_ac6、τ_ac7，τ_ac1＜τ_ac2＜τ_ac3＜τ_ac4＜τ_ac5＜τ_ac6＜τ_ac7(ii) a n is the number of the nth stage starting from the high-temperature alternating ageing heating, and n is more than or equal to 1 and less than or equal to 7 (namely n is 1, 2, 3, 4, 5, 6 or 7); tau is_ac1Heating for min/time or h/time at the critical first stage of high-temperature alternating ageing; tau is_ac0The critical point is that the time level difference is decreased by high-temperature alternating aging heating for min/time or h/time, and the time level difference is the same and unchanged specific numerical value.

In the embodiment of the invention, the critical starting high-temperature alternate aging heat treatment final cooling mode of the first half part of the second part is as follows: the furnace door is opened or other cooling modes are adopted to rapidly cool along with the furnace.

In the invention, the mathematical relation between the critical low-temperature annealing heating temperature Tlac and the low-temperature annealing minimum theoretical heating temperature Tlactmin and the low-temperature annealing maximum theoretical heating temperature Tlacmax is as follows:

Tlactmin+(80～90)℃≤Tlac≤Tlacmax–(10～15)℃

in the formula, Tlac is the critical low-temperature annealing heating temperature and is DEG C; tlactmin is the lowest theoretical heating temperature of low-temperature annealing at DEG C; tlacmax is the maximum theoretical heating temperature of low temperature annealing at C.

In an embodiment of the present invention, the second half-half critical annealing temperature cannot be too high or too low: when the annealing temperature is too high and is higher than the high-temperature annealing temperature Tha which is more than 850-1200 ℃ and the medium-temperature annealing temperature Tma which is 680-850 ℃, the effect of removing the residual cold and hot processing stress of the material is good, but the deformation of the austenitic stainless steel is large, the heating time is long, the negative effects of solid solution and aging are newly generated, the problems that an independent process is required to be arranged and is not suitable to be used as a final process (only suitable to be used as an intermediate process before aging after solid solution or suitable to be used as a process without solid solution and aging heat treatment) and the like cannot be solved, and the problems that the temperature quickly avoids 700 ℃ -815 ℃ (sensitized intercrystalline corrosion critical temperature zone), 850 ℃ -900 ℃ (sigma phase critical temperature zone is formed, the critical temperature zone of a small amount of precipitated (Fe, Cr, Ni, Mn, W, Mo) C composite alloy carbide or precipitated lamellar carbide), 940 ℃ (FeS-FeO eutectic melting, 985 ℃ (Fe-FeS eutectic melting point and dissolution genetic critical temperature region), 1083 ℃ (weakening phase copper alloy dissolution and genetic critical temperature region) or 1164 ℃ (FeS-MnS eutectic melting point and dissolution genetic critical temperature region), and the like; when the annealing temperature is less than 275 ℃, although 450 ℃ -500 ℃ (a chromium-poor precipitation critical temperature zone and a large-granularity needle-rod-shaped carbide precipitation critical temperature zone), 475 ℃ (a cold-brittleness critical temperature zone and a large-granularity needle-rod-shaped carbide precipitation critical temperature zone), 550 ℃ -670 ℃ (graphitization, intercrystalline corrosion or crystal-brittle fracture critical temperature zone) and the like can be effectively and quickly avoided, and the method does not generate new negative effects of solid solution or aging heat treatment while carrying out low-temperature annealing heat treatment, has extremely small deformation of austenitic stainless steel, is beneficial to maintaining the strengthening effect of tarnish resistance after the solid solution or aging heat treatment, and is also suitable for any intermediate process and final process, an independent low-temperature annealing process is required to be arranged, the heating time is longer, and the effect of removing the residual cold and hot processing stress of the material is poorer, therefore, the critical low-temperature annealing heat treatment method is continuously adopted after, finally, the method is more favorable for obtaining the optimized heat treatment hardness range of the austenitic stainless steel, reducing the residual cold and hot processing stress and deformation, meeting the service performance requirement, improving the anti-tarnishing capacity and improving the heat treatment efficiency.

In the embodiment of the invention, the second half of the second half is subjected to the critical low temperature annealing heating time tau_lacHeating time tau of low-temperature annealing theory_latThe mathematical relationship of (a) is: tau is_lac＝τ_lat；

In the formula tau_lacCritical low temperature annealing heating time, min or h; tau is_latThe heating time is the theoretical heating time of low-temperature annealing, min or h.

In the embodiment of the present invention, the heating time of the critical low-temperature annealing should not be too short in principle but should not be too long: if the time is too short, the effects of reducing the residual cold and hot processing stress capability and quality of the austenitic stainless steel are poor although the annealing efficiency can be improved and the heat energy consumption can be reduced; when the temperature is too long, the capability of reducing the residual cold and hot processing stress of the austenitic stainless steel is good, the quality is good, but the annealing efficiency is low and the heat energy consumption is large. In fact, the heating time of the critical low-temperature annealing is beneficial to improving the capability and quality of reducing the residual cold and hot processing stress of the austenitic stainless steel, and the annealing efficiency is not reduced or the heat energy consumption is not related to the heating time of the critical low-temperature annealing, because the heat source of the critical low-temperature annealing is realized by the residual heat after the temperature reduction and the cooling of the previous critical aging process.

In an embodiment of the present invention, the final cooling manner of the second half-half critical annealing heat treatment is as follows: the furnace is cooled by opening the furnace door or other cooling modes, or directly taken out of the furnace and cooled in room-temperature water or room-temperature air.

In an embodiment of the present invention, the second part of the critical process starts with a high temperature alternate aging and critical annealing combined heat treatment, which comprises the following processes: the second part front half begins with a high temperature alternate aging heat treatment method, comprising the following processes: 1) the 1 st critical process is started at high temperature and ended at high temperature alternating aging process: firstly, performing the first half critical starting at high temperature and ending at low temperature without alternating aging process for the first time 1: heating and preserving the austenitic stainless steel in a heating furnace at the highest critical aging temperature within a specified time, then continuously rapidly cooling the austenitic stainless steel to the middle aging temperature for heating and preserving the austenitic stainless steel, and then continuously rapidly cooling the austenitic stainless steel to the lowest final aging temperature for heating and preserving the austenitic stainless steel; then, the second half of the 1 st time is continued, wherein the low temperature is started and the high temperature alternating aging process is ended: the austenitic stainless steel is continuously and rapidly heated from the critical aging lowest temperature to the critical aging middle temperature in the heating furnace within the specified time for heating and heat preservation, and then the austenitic stainless steel is rapidly heated from the critical aging middle temperature to the critical aging highest temperature in the heating furnace within the specified time for heating and heat preservation (the 1 st time of the critical temperature begins and ends with the high temperature alternating aging process); 2) after the 1 st critical starting from the high temperature and ending the high temperature alternating aging process, the 2 nd, 3 rd, … … th and Nth critical alternating aging processes are carried out again: critical alternating aging for 2 times, sequentially and reversely repeating the first half part of critical starting from low temperature and ending at high temperature alternating aging for 1 time (the critical starting from high temperature and ending at low temperature alternating aging for 2 times), critical alternating aging for 3 times, sequentially and reversely repeating the critical alternating aging for 2 times (the critical starting from low temperature and ending at high temperature alternating aging for 3 times), … …, and so on, and critical alternating aging for N times, sequentially and reversely repeating the critical alternating aging for 1 time (the critical starting from high temperature and ending at low temperature or the critical starting from low temperature and ending at high temperature alternating aging for N times); 3) and (3) continuing the final cooling process after the 2 nd time, the 3 rd time, the … … th time and the Nth time of the critical start at the high temperature and the low temperature or the critical start at the low temperature and the high temperature alternating aging process are all ended: the austenitic stainless steel is rapidly cooled to the critical annealing temperature from the highest critical aging temperature or the lowest critical aging temperature by opening a furnace door or other cooling modes along with the furnace (the first half part of the second part is critical and begins to finish the high-temperature alternating aging heat treatment process completely); the second half of the second part is subjected to critical annealing heat treatment, and the method comprises the following steps: 1) critical annealing and heating process: after the critical high-temperature alternate aging heat treatment process is completely finished, continuously heating and preserving the austenitic stainless steel in a heating furnace within the range of the critical annealing temperature Tlac within a specified time; 2) critical annealing and final cooling process: and after the critical annealing heating step is finished, a furnace door is opened or other cooling modes are adopted to rapidly cool the austenitic stainless steel from the critical annealing temperature Tlac range to (150-100) DEG C along with the furnace, and then the austenitic stainless steel is taken out of the furnace and cooled in room temperature water or room temperature air (the second half of the critical annealing heat treatment process is completely finished, and the second half of the critical annealing heat treatment process is started from the high-temperature alternating aging and critical annealing composite heat treatment process and is also completely finished).

According to the technical scheme, the invention fundamentally solves the problems of the special heat treatment technology theory and practice that the traditional mainstream austenitic stainless steel technical method cannot solve the problems of poor quality stability, low qualified product rate, low hardness (or low mechanical property) and poor consistency, poor anti-tarnishing capacity, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components and parts, high cost and the like.

Although the invention is researched by taking the heat treatment method of austenitic stainless steel (the used heating equipment is the conventional box-type resistance heating furnace) as a research object, the invention is also applicable to heat treatment methods of other types of stainless steel, high-temperature alloy and the like (the heating equipment can also be selected from other types of resistance heating furnaces, high-medium and low-frequency heating furnaces, salt bath heating furnaces, gas-fuel oil heating furnaces, fluid particle heating furnaces, vacuum heating furnaces and the like); similarly, the method is also suitable for heat treatment methods related in the technical fields of hot working engineering such as austenitic stainless steel smelting, steel rolling, forging, heat treatment and the like related in steel mills and manufacturing plants; meanwhile, it should be noted that: it will be apparent to those skilled in the art that several arrangements, combinations, modifications, improvements (especially, the heating temperatures and times for solution, aging, and annealing, and the cooling media can be properly adjusted or changed according to the grades, the use properties, and the heating equipment of austenitic stainless steel) and the like can be made without departing from the technical principle of the present invention.