阅读说明：本技术 一种气阀用高硬度3j40合金棒材及其制造方法 (High-hardness 3J40 alloy bar for air valve and manufacturing method thereof ) 是由 毛福祥 束文武 梁小刚 王林涛 张建国 于 2021-07-19 设计创作，主要内容包括：本发明涉及一种气阀用高硬度3J40合金棒材及其制造方法,该气阀用高硬度3J40合金棒材晶粒度为细于5级且级差在2级以内,无条带晶粒；同时棒材力学性能稳定,且硬度HV≥370。(The invention relates to a high-hardness 3J40 alloy bar for an air valve and a manufacturing method thereof, wherein the grain size of the high-hardness 3J40 alloy bar for the air valve is finer than 5 grade, the grade difference is within 2 grade, and no strip grain exists; meanwhile, the mechanical property of the bar is stable, and the hardness HV is more than or equal to 370.)

1. A high-hardness 3J40 alloy bar for an air valve is characterized by comprising the following chemical components in percentage by weight:

C：≤0.03％；

Si：≤0.2％；

Mn：≤0.1％；

P：≤0.01％；

S：≤0.01％；

Cu：≤0.5％；

Fe：≤1.0％；

Al：3.2～3.6％；

Cr：39.0～41.0％；

ni: and (4) the balance.

2. The high-hardness 3J40 alloy bar for gas valves as claimed in claim 1, wherein the grain size is finer than 5 grade and within 2 grade, the bar has no banding grains, and the hardness HV is more than or equal to 370.

3. The method for manufacturing the high-hardness 3J40 alloy bar for the air valve according to claim 1 or 2, comprising the steps of: batching → vacuum induction melting → pouring electrode → thermal annealing → electrode surface treatment → protective atmosphere electroslag remelting → steel ingot homogenizing annealing → forging cogging → coping → forged product → solid solution treatment → straightening and polishing → nondestructive inspection.

4. The method for manufacturing the high-hardness 3J40 alloy bar for the gas valve according to claim 3, wherein the hot-feed annealing comprises: after the electrode is poured, demolding at high temperature, and sending the electrode to a heating furnace for annealing to reduce the structural stress of the electrode; heating the furnace to 650 ℃, heating the electrode in the furnace for 3h to 1180 ℃, keeping the temperature for 2h, cooling the furnace to 800 ℃, discharging and air cooling.

5. The method for manufacturing the high-hardness 3J40 alloy bar for the gas valve according to claim 4, wherein the homogenizing annealing comprises: after electroslag remelting is finished, carrying out homogenization annealing to reduce component segregation and enable the structure to be more uniform; the specification of the electroslag ingot is phi 375; the annealing temperature of the electroslag ingot is 1190 ℃, and the temperature is kept for 36 h.

6. The method for manufacturing the high-hardness 3J40 alloy bar for the air valve according to claim 5, wherein the forging and cogging comprises: after the homogenization annealing is finished, forging and cogging are carried out, and the cogging specification is 140-180.

7. The method for manufacturing the high-hardness 3J40 alloy bar for the air valve according to claim 6, wherein the forged product comprises: grinding clean square billets, re-melting and heating at the heating temperature of 1100-1120 ℃, and forging finished products according to production requirements to obtain finished bars.

8. The method for manufacturing the high-hardness 3J40 alloy bar for the air valve according to claim 7, wherein the solution treatment comprises: and after the finished bar is forged, carrying out solid solution treatment to reduce residual stress and fully dissolve the strengthening elements into the matrix so as to obtain a supersaturated solid solution.

9. The method for manufacturing the high-hardness 3J40 alloy bar for the air valve according to claim 8, wherein the non-destructive inspection comprises: the polished rods were subjected to ultrasonic flaw detection one by one, and the acceptance grade was according to GB/T4162 grade AA.

Technical Field

The invention relates to the field of manufacturing of nickel-based high-temperature alloy materials, in particular to a high-hardness 3J40 alloy bar for a gas valve and a manufacturing method thereof.

Background

3J40 is Ni-Cr based alloy material, on one hand, because the Cr content and Al content are higher, the alloy has the characteristics of high hardness and good wear resistance; therefore, the method is widely applied to shaft tip parts such as mechanical instruments. On the other hand, the alloy material has poor thermoplasticity and high hot-forming difficulty, and large-size alloy bars are not produced successfully.

The valve alloy is mainly used for manufacturing parts such as internal combustion engine valves and the like, the use environment is very harsh, the requirement on the hardness of the alloy material is higher, and the high hardness means that the material has better wear resistance. The existing Nimonic 80A gas valve steel material cannot meet the use requirements of high-end customers more and more. The high-hardness 3J40 alloy bar trial-manufactured at this time has a chromium content of about 40%, and the extremely high chromium content means that the corrosion resistance of the material is more excellent, and the chromium-rich alpha-Cr phase can increase the hardness of a matrix; the aluminum content is 3.3 percent, and the aluminum is used as a strengthening product generating element, and the higher aluminum content further improves the matrix hardness of the material.

In actual production, how to effectively control the component uniformity of the 3J40 alloy, reduce the segregation degree of the alloy and further improve the hot working plasticity of the alloy is a technical difficulty to be solved urgently.

Disclosure of Invention

The invention aims to provide a high-hardness 3J40 alloy bar for an air valve and a manufacturing method thereof, wherein the grain size of the high-hardness 3J40 alloy bar for the air valve is finer than 5 grade, the grade difference is within 2 grade, and strip grains are avoided; meanwhile, the mechanical property of the bar is stable, and the hardness HV is more than or equal to 370.

In order to solve the technical problems, the high-hardness 3J40 alloy bar for the air valve provided by the invention comprises the following chemical components in percentage by weight:

C：≤0.03％；

Si：≤0.2％；

Mn：≤0.1％；

P：≤0.01％；

S：≤0.01％；

Cu：≤0.5％；

Fe：≤1.0％；

Al：3.2～3.6％；

Cr：39.0～41.0％；

ni: and (4) the balance.

Furthermore, the grain size of the high-hardness 3J40 alloy bar for the air valve is finer than 5 grade, the grade difference is within 2 grade, and strip grains do not exist; meanwhile, the mechanical property of the bar is stable, and the hardness HV is more than or equal to 370.

A manufacturing method of a high-hardness 3J40 alloy bar for a gas valve comprises the following steps:

batching → vacuum induction melting → pouring electrode → thermal annealing → electrode surface treatment → protective atmosphere electroslag remelting → steel ingot homogenizing annealing → forging cogging → coping → forged product → solid solution treatment → straightening and polishing → nondestructive inspection.

Further, the hot-feed annealing includes: after the electrode is poured, demolding at high temperature, and sending the electrode to a heating furnace for annealing to reduce the structural stress of the electrode; heating the furnace to 650 ℃, heating the electrode in the furnace for 3h to 1180 ℃, keeping the temperature for 2h, cooling the furnace to 800 ℃, discharging and air cooling.

Further, the homogenizing annealing includes: after electroslag remelting is finished, carrying out homogenization annealing to reduce component segregation and enable the structure to be more uniform; the specification of the electroslag ingot is phi 375; the annealing temperature of the electroslag ingot is 1190 ℃, and the temperature is kept for 36 h.

Further, the forging cogging includes: after the homogenization annealing is finished, forging and cogging are carried out, and the cogging specification is 140-180.

Further, the coping includes: and the defects on the surface of the square billet are polished to be clean without crack defects.

Further, the forged product includes: grinding clean square billets, re-melting and heating at the heating temperature of 1100-1120 ℃, and forging finished products according to production requirements to obtain finished bars.

Further, the solution treatment includes: and after the finished bar is forged, carrying out solid solution treatment to reduce residual stress and fully dissolve the strengthening elements into the matrix so as to obtain a supersaturated solid solution.

Further, the non-destructive inspection comprises: the polished rods were subjected to ultrasonic flaw detection one by one, and the acceptance grade was according to GB/T4162 grade AA.

The invention has the technical effects that: compared with the prior art, in the process of smelting a steel ingot from the high-hardness 3J40 alloy, the high-hardness 3J40 alloy bar for the air valve and the manufacturing method thereof adopt the raw materials such as metal chromium, electrolytic nickel and pure aluminum to smelt so as to reduce impurity elements in the steel; demolding the electrode at high temperature, and carrying out hot conveying annealing after demolding; carrying out high-temperature long-time homogenization annealing treatment on the steel ingot after electroslag is finished, slowing down segregation and enabling the obtained blank structure to be more uniform; after the alloy electrode is poured, hot conveying annealing is carried out, so that excessive stress of an electrode structure is prevented, and cracking is prevented from occurring in electroslag production; solution treatment can reduce the material, reduce residual stress, and enable the strengthening elements to be fully dissolved in the matrix to obtain a supersaturated solid solution.

Drawings

The invention is described in further detail below with reference to the drawings of the specification:

FIG. 1 is a metallographic photograph of grain size of a 3J40 bar having high hardness for gas valve batch 1 of example 1;

FIG. 2 is a metallographic photograph of the grain size of a 3J40 bar having high hardness for use in gas valve batch 2 according to example 1;

Detailed Description

Example 1

In this example, 2 batches of high-hardness 3J40 alloy rods for gas valves were produced, and they were subjected to compounding → vacuum induction melting → casting of electrode → hot transfer annealing → electrode surface treatment → protective atmosphere electroslag melting → steel ingot diffusion annealing → forging cogging → coping → forged product → solution heat treatment → straightening and polishing → non-destructive inspection.

And carrying out homogenizing annealing on the steel ingot obtained by smelting to obtain the steel ingot with uniform components and better plasticity. The chemical composition of the obtained steel ingot is shown in table 1 below.

Table 1 test results of chemical components of steel ingots obtained in examples

And forging the steel ingots obtained in the embodiment by smelting to obtain forging blanks with the specification of 140 and 180.

And polishing the forging blank, then heating and forging a finished product, controlling the heating temperature to be 1100-1120 ℃, controlling the final fire total deformation to be 50-70%, and carrying out first fire forming to obtain a forging round blank with the diameter phi of 60-phi 120.

And (3) carrying out heat preservation on the obtained forged round billet for 1h at 1020 +/-10 ℃, carrying out water-cooling solution heat treatment, and then straightening and polishing until the surface has no defects such as scratches, cracks, peeling and the like.

Sampling the heat-treated bar, marking the bar with a serial number, heating a sample to 800 ℃ in a sample heat treatment box furnace to 10 ℃, preserving the heat for 24 hours, and cooling in air; respectively carrying out grain size detection and room temperature tensile property detection on the obtained samples; the grain size test results are shown in FIG. 1, and the mechanical property test results are shown in Table 2.

TABLE 2 results of room-temperature elongation and hardness grain size measurement of high-hardness 3J40 rods for air valves obtained in example

For comparison, the room temperature tensile, hardness and grain size detection results of the prior art relatively close GH80A bars are shown in Table 3, and the results obtained in Table 3 show that the 3J40 bars have better grain size, hardness and room temperature tensile properties than the prior GH80A bars.

TABLE 3GH80A measurement results of tensile strength, hardness and grain size of bar material at room temperature

It should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And such obvious variations or modifications which fall within the spirit of the invention are intended to be covered by the scope of the present invention.