阅读说明：本技术 大直径高碳铬不锈钢锻件珠光体均匀分布的热处理方法 (Heat treatment method for large-diameter high-carbon chromium stainless steel forging with uniformly distributed pearlite ) 是由 王小军 刘国平 周预平 罗波 汤晶晶 陈先华 孙赛刚 于 2019-09-23 设计创作，主要内容包括：本发明涉及一种大直径高碳铬不锈钢锻件珠光体均匀分布的热处理方法,先将熔炼分析符合要求的G102Cr18Mo锻件加热保温,升温至1050～1060℃均温后保温,出炉空冷到600～650℃,进650℃的加热炉,再炉冷到500～550℃,并保温进行均质碳分配,升温到650±10℃性能回火,炉冷到200℃后出炉空冷。本发明采用分阶段加热控温、控冷及在500～550℃进行碳分配,可在马氏体不锈钢材料上获得均质珠光体组织。本发明生产的大直径G102Cr18Mo高碳铬蘑菇头不锈钢锻件机械性能指标高,细粒状珠光体组织均匀分布；满足GB/T3086-2008标准技术要求；能满足于大型水利电站闸门施工技术要求。(The invention relates to a heat treatment method for uniform distribution of pearlite of a large-diameter high-carbon chromium stainless steel forging, which comprises the steps of heating and preserving heat of a G102Cr18Mo forging meeting the requirement in smelting analysis, heating to 1050-1060 ℃ for temperature equalization, preserving heat, discharging from a furnace, cooling to 600-650 ℃, feeding into a heating furnace at 650 ℃, then cooling to 500-550 ℃ for temperature equalization, preserving heat for homogeneous carbon distribution, heating to 650 +/-10 ℃ for performance tempering, discharging from the furnace, cooling to 200 ℃ for air cooling. According to the invention, the homogeneous pearlite structure can be obtained on the martensitic stainless steel material by heating and controlling the temperature and cooling in stages and carrying out carbon distribution at 500-550 ℃. The large-diameter G102Cr18Mo high-carbon chromium mushroom head stainless steel forging produced by the method has high mechanical property index, and fine grained pearlite structures are uniformly distributed; the technical requirements of GB/T3086-2008 standard are met; can meet the technical requirements of the gate construction of large hydropower stations.)

1. The heat treatment method for the uniform distribution of pearlite of the large-diameter high-carbon chromium stainless steel forging is characterized by comprising the following steps of: the large-diameter high-carbon chromium stainless steel forging is a G102Cr18Mo high-carbon chromium stainless steel forging with the nominal diameter or the effective section diameter of more than 160 mm;

the chemical components of the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging, wt, are as follows by smelting analysis: 0.95 to 1.10 percent of C, 0.20 to 0.78 percent of Si, 0.20 to 0.78 percent of Mn, 0.005 to 0.034 percent of P, 0.003 to 0.028 percent of S, 16.02 to 17.95 percent of Cr, 0.40 to 0.70 percent of Mo, 0.03 to 0.25 percent of Ni and 0.03 to 0.24 percent of Cu;

the heat treatment comprises the following specific steps:

1) putting the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging into a heating furnace, heating to 600-650 ℃ at the speed of 45-55 ℃/h, and preserving heat, wherein the heat preservation time is calculated according to 10h/100 mm; then raising the temperature to 1050-1060 ℃, and then carrying out temperature equalization and heat preservation, wherein the temperature equalization time is calculated according to 2h/100mm, and the heat preservation time is 1/2 of the temperature equalization time;

the 100mm refers to the effective section diameter of the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging;

2) discharging the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging subjected to temperature equalization and heat preservation in the step 1), and air-cooling to 600 ℃;

3) placing the large-diameter G102Cr18Mo high-carbon chromium stainless steel forged piece subjected to air cooling in the step 2) into a heating furnace at 650 ℃, cooling to 500-550 ℃ along with the furnace, and performing homogeneous carbon distribution, wherein the heat preservation time is calculated according to 1h/100 mm; then heating to 650 +/-10 ℃ for temperature equalization and heat preservation, wherein the temperature equalization time is calculated according to 3.0h/100mm, and the heat preservation time is 1/2 of the temperature equalization time; cooling to 200 ℃ along with the furnace;

the 100mm refers to the effective section diameter of the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging;

4) and (3) discharging the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging which is cooled to 200 ℃ along with the furnace in the step 3), and air-cooling to obtain the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging which has uniformly distributed pearlite structures and does not have harmful twin carbide.

2. The heat treatment method for large-diameter high-carbon chromium stainless steel forgings with uniformly distributed pearlite according to claim 1, is characterized in that: and in the step 2) and the step 4), air cooling refers to discharging the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging, and placing the forging in the air space at room temperature for natural cooling.

3. The heat treatment method for large-diameter high-carbon chromium stainless steel forgings with uniformly distributed pearlite according to claim 1, is characterized in that: and 3) furnace cooling, namely placing the large-diameter high-carbon chromium stainless steel forging into the heating furnace with the heat preservation completed, closing the furnace door, and slowly cooling without heating.

Technical Field

The invention relates to a heat treatment method, in particular to a heat treatment method for uniformly distributing pearlite of a large-diameter high-carbon chromium stainless steel forging. The large-diameter high-carbon chromium stainless steel forging is a G102Cr18Mo high-carbon chromium stainless steel forging with the nominal diameter or the effective section diameter of more than 160 mm.

Background

The G102Cr18Mo high-carbon chromium stainless steel material has good corrosion resistance, high temperature resistance and low temperature resistance. The highest using temperature can reach 427 ℃, and the lowest using temperature can reach below-253 ℃.

The G102Cr18Mo high-carbon chromium stainless steel is developed by adding Mo on the basis of 9Cr18 steel, and has higher hardness and tempering resistance than 9Cr18 steel. The critical points (approximate values) of the steel are AC1: 815-865 ℃, Ar1: 665-765 ℃, Ms:145 ℃. The steel is spherical pearlite and carbide after being completely annealed, but has low hardness and strength indexes, and is easy to form chain or net-shaped carbide; the traditional normalizing and tempering process is adopted, and bainite and martensite low-temperature transformation structures and the like are easily formed due to good hardenability. Therefore, a pearlite structure with high hardness and uniform distribution is obtained on a G102Cr18Mo steel forging with a large section diameter, and the difficulty is high by adopting a traditional method.

The G102Cr18Mo mushroom head stainless steel is developed and applied to the manufacture of hydraulic engineering gates, and is mainly applied to the hydraulic gates by using 35CrMo materials at home. The G102Cr18Mo mushroom head stainless steel consists of a hemisphere and a columnar platform. If the diameter of the hemisphere is S phi 1200mm, the height of the columnar platform is 200mm, the diameter of the platform is phi 1400mm, and the effective section diameter is 800 mm.

Disclosure of Invention

The invention aims to provide a heat treatment method for uniformly distributing pearlite of a large-diameter high-carbon chromium stainless steel forging with uniformly distributed fine-grained pearlite structures and without twin carbide.

The purpose of the invention is realized by the following steps: the heat treatment method for the uniform distribution of pearlite of the large-diameter high-carbon chromium stainless steel forging, wherein the large-diameter high-carbon chromium stainless steel forging is a G102Cr18Mo high-carbon chromium stainless steel forging with the nominal diameter or the effective section diameter of more than 160 mm;

the chemical components of the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging, wt, are as follows by smelting analysis: 0.95 to 1.10 percent of C, 0.20 to 0.78 percent of Si, 0.20 to 0.78 percent of Mn, 0.005 to 0.034 percent of P, 0.003 to 0.028 percent of S, 16.02 to 17.95 percent of Cr, 0.40 to 0.70 percent of Mo, 0.03 to 0.25 percent of Ni and 0.03 to 0.24 percent of Cu. The heat treatment comprises the following specific steps:

1) putting the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging into a heating furnace, heating to 600-650 ℃ at the speed of 45-55 ℃/h, and preserving heat, wherein the heat preservation time is calculated according to 10h/100 mm; then raising the temperature to 1050-1060 ℃, and then carrying out temperature equalization and heat preservation, wherein the temperature equalization time is calculated according to 2h/100mm, and the heat preservation time is 1/2 of the temperature equalization time;

the 100mm refers to the effective section diameter of the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging;

2) discharging the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging subjected to temperature equalization and heat preservation in the step 1), and air-cooling to 600 ℃;

3) placing the large-diameter G102Cr18Mo high-carbon chromium stainless steel forged piece subjected to air cooling in the step 2) into a heating furnace at 650 ℃, cooling to 500-550 ℃ along with the furnace, and performing homogeneous carbon distribution, wherein the heat preservation time is calculated according to 1h/100 mm; then heating to 650 +/-10 ℃ for temperature equalization and heat preservation, wherein the temperature equalization time is calculated according to 3.0h/100mm, and the heat preservation time is 1/2 of the temperature equalization time; cooling to 200 ℃ along with the furnace;

the 100mm refers to the effective section diameter of the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging;

4) and (3) discharging the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging which is cooled to 200 ℃ along with the furnace in the step 3), and air-cooling to obtain the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging which has uniformly distributed pearlite structures and does not have harmful twin carbide.

The invention adopts a heat treatment method of temperature control and cold control to the large-diameter G102Cr18Mo high-carbon chromium stainless steel mushroom head forging; and (3) carrying out homogeneous carbon distribution by adopting heat preservation at a medium temperature range of 500-550 ℃ to ensure that carbides are fully precipitated and a low-temperature transformation structure is cut off. Thus obtaining the homogeneously distributed fine grain pearlite structure on the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging.

The invention solves the problem that harmful twin carbide is easy to appear in the production of large-diameter G102Cr18Mo high-carbon chromium stainless steel, and solves the problem that manufacturers with the nominal diameter or effective diameter larger than 160mm cannot keep any performance index.

The large-diameter G102Cr18Mo high-carbon chromium stainless steel forging subjected to heat treatment of the invention has the tensile strength of 590-835 MPa and the Brinell hardness HB of the body of 250-300. The performance index can meet the GB/T3086-2008 standard technical requirement corresponding to the effective diameter section of 5-160 mm which is only produced by few bearing manufacturers at home at present.

The invention has strong operability, not only refines the crystal grains, but also can control the appearance of low-temperature bainite or martensite transformation structure, avoids harmful reticular carbide structure and completely obtains good pearlite high-temperature transformation structure with comprehensive mechanical properties. The obtained large-diameter G102Cr18Mo steel has high hardness and corrosion resistance, and can be used for manufacturing bearings and gate parts which work in a corrosive environment and in a non-lubricating strong oxidizing atmosphere; the method is increasingly applied to the navigation and hydraulic engineering industries, and has wide application prospect.

The large-diameter G102Cr18Mo mushroom head stainless steel processed by the method can meet the technical requirements of the large hydropower station water gate mushroom head forge piece.

Drawings

FIG. 1 is a diagram showing a homogeneous distribution pearlite structure by heat treatment in example 1,

FIG. 2 is a diagram showing a pearlite structure in a homogeneous distribution by heat treatment in example 2,

FIG. 3 is a diagram of a homogeneously distributed pearlite structure by heat treatment in example 3,

FIG. 4 is a drawing showing a structure of tempered martensite heat-treated in comparative example 1,

FIG. 5 is a graph of a white network carbide + black pearlite structure heat-treated by comparative example 2.

Detailed Description

The large-diameter G102Cr18Mo high-carbon chromium stainless steel forging meeting the requirements of smelting analysis is firstly placed into a heating furnace, the heating is carried out at the heating speed of 45-55 ℃/h to 600-650 ℃, the heat preservation is carried out, the temperature is raised to 1050-1060 ℃, the heat preservation is carried out, the forging is discharged from the furnace and cooled to 600-650 ℃, the forging is heated to 650 ℃, the heating furnace is then carried out after the forging is heated to 500-550 ℃, the heat preservation is carried out, the homogeneous carbon distribution is realized, the temperature is raised to 650 +/-10 ℃ for performance tempering, the forging is then discharged from the furnace and cooled to 200 ℃, and the G102Cr18Mo high-carbon chromium stainless steel forging with the pearlite distributed homogeneously is obtained.

The chemical components wt% of the G102Cr18Mo high-carbon chromium stainless steel forging used in the invention are as follows by smelting analysis: 0.95 to 1.10 percent of C, 0.20 to 0.78 percent of Si, 0.20 to 0.78 percent of Mn, 0.005 to 0.034 percent of P, 0.003 to 0.028 percent of S, 16.02 to 17.95 percent of Cr, 0.40 to 0.70 percent of Mo, 0.03 to 0.25 percent of Ni and 0.03 to 0.24 percent of Cu.

The 100mm refers to the effective cross-sectional diameter of the material forging for heat treatment.

The air cooling refers to discharging the large-diameter G102Cr18Mo high-carbon chromium stainless steel forging, and naturally cooling the forging in the air at room temperature.

And the furnace cooling means that the large-diameter high-carbon chromium stainless steel forging is placed in a heating furnace which is subjected to heat preservation, the furnace door is closed, and the furnace is slowly cooled under the condition of not heating.

The present invention is described in detail below with reference to specific examples.