Duplex solid solution treatment process for 68NiCrWCoTiAl alloy

Abstract

The present application relates to a kind of duplex solid solution treatment process of 68NiCrWCoTiAl alloy, the process uses " cold loading furnace, first 1160 ℃ × 1h heat preservation, air cooling, then cold loading furnace, 1080 ℃ × 1h heat preservation, water cooling "Duplex solid solution treatment process, can avoid high crack tendency difficult 68NiCrWCoTiAl alloy material production process when internal crack is generated during solid solution treatment, and stable realization final performance requirement, solid solution treatment qualified rate reaches 100%, finished product quality is stable, without quality hidden danger risk, with feasibility, high reliability, high finished product rate, the advantages of good quality, provide a solution for the normal manufacture of the alloy material.The process described in the present application can be applied to batch production of products.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of heat treatment of special alloy, and relates to a double solid solution treatment process for preventing internal cracks during solid solution treatment of high-crack-prone difficult-to-machine 68NiCrWCoTiAl alloy and stabilizing the final performance. BACKGROUND

[0002] Special alloy mainly includes high-temperature alloy, corrosion-resistant alloy, metal functional material, special stainless steel, etc. The special alloy material usually includes bar, strip, wire, plate, strip, pipe, etc. The specifications are various, and the sizes are different. The bar and strip products usually need to be subjected to solid solution treatment before cold drawing or after finishing to achieve the purpose of softening the alloy blank or finished product performance.

[0003] However, there are some problems in the solid solution treatment of a small number of special grades in special alloy (especially in high-temperature alloy). The 68NiCrWCoTiAl alloy is prone to internal cracks and unqualified final performance during solid solution treatment, resulting in product scrap and low yield. For the 68NiCrWCoTiAl alloy, there are two solid solution treatment processes currently used, both of which are single solid solution treatment processes. One is the "cold charging, 1160℃×1h holding, water cooling" (A process) single solid solution treatment process, which has the characteristics of high final performance qualification rate, but the proportion of internal cracks is as high as about 30%, the scrap rate due to internal cracks is high, and the total scrap rate is high. The other is the "cold charging, 1080℃×1h holding, water cooling" (B process) single solid solution treatment process, which has the characteristics of reduced internal crack proportion, only about 15%, reduced scrap rate due to internal cracks, but reduced yield strength and plasticity, and easy to be out of tolerance due to unqualified final performance, resulting in no obvious change in total scrap rate and still high. When using these two single solid solution treatment processes, although each of them can be successful, either mainly produces internal crack problem or mainly produces unqualified final performance problem, which will cause product scrap and low yield.

[0004] It can be seen that after the solid solution treatment of the 68NiCrWCoTiAl alloy, the first problem is the internal crack, which is almost transverse crack, the proportion is 15-30%, which seriously affects the product yield and has serious quality risks. The second problem is the final performance qualification rate, which also affects the product yield. The influence of the two together causes the product yield to be significantly low. The reason is that the content of carbon, tungsten, molybdenum, cobalt, titanium and aluminum in the 68NiCrWCoTiAl alloy is very high, so it has high crack tendency and is difficult to process. The conventional process easily causes the alloy yield to be low, and the finished product quality is also easy to have serious uncertainty, which becomes a technical obstacle in the production of alloy materials. It is a problem that the technical personnel in the field pay close attention to to research a new solid solution treatment process, solve the problems of easy internal crack and unqualified final performance, and fundamentally improve the yield. SUMMARY

[0005] The application provides a duplex solid solution treatment process for high crack tendency and difficult to process 68NiCrWCoTiAl alloy, which adopts the duplex solid solution treatment process of "cold charging, first 1160℃×1h holding, air cooling, then cold charging, 1080℃×1h holding, water cooling", which does not produce internal cracks and stably realizes the final performance requirements, and the solid solution treatment qualification rate is improved to 100%. The process is suitable for the solid solution treatment of 68NiCrWCoTiAl alloy, has good feasibility and reliability, high yield and high quality.

[0006] The technical scheme of the application is:

[0007] The duplex solid solution treatment process for 68NiCrWCoTiAl alloy comprises the following steps:

[0008] 1) First association solid solution treatment

[0009] S1, the to-be-treated material is charged into the heat treatment furnace when the furnace temperature is ≤100℃; the charging position is in the effective working area of the heat treatment furnace;

[0010] S2, the furnace temperature of the heat treatment furnace is raised to the holding temperature 1160±5℃, and holding for 1h;

[0011] S3, the to-be-treated material is discharged, and naturally cooled to room temperature-100℃ in the air;

[0012] 2) Second association solid solution treatment

[0013] S4, the to-be-treated material after the first association solid solution treatment is charged into the heat treatment furnace when the furnace temperature is ≤100℃; the charging position is in the effective working area of the heat treatment furnace;

[0014] S5, the furnace temperature of the heat treatment furnace is raised to the holding temperature 1080±5℃, and holding for 1h;

[0015] S6, the material to be treated is discharged from the furnace and rapidly placed in water for water cooling within ≤90 seconds.

[0016] The heat treatment furnace in steps S1 and S4 is an electric heating heat treatment furnace.

[0017] The effective working zone in steps S1 and S4 is a uniform temperature zone.

[0018] The furnace temperature of the heat treatment furnace in steps S1 and S4 should be detected for uniformity, and the furnace temperature deviation and uniformity should meet the requirement of ±10℃.

[0019] The furnace loading in steps S1 and S4 should place a 30-50mm high iron pad under the material to be treated.

[0020] The temperature rising speed of the heat treatment furnace in steps S2 and S5 to the holding temperature is 280±30℃ / h.

[0021] The rapid water cooling in step S6 is that the time from furnace discharge to water entry is ≤90 seconds, and the cooling water should be kept in a flowing state.

[0022] The cooling water temperature in the rapid water cooling in step S6 is ≤30℃, and the cooling water temperature after the material to be treated is cooled after water entry should be ≤35℃.

[0023] The mass percentage of each component of the 68NiCrWCoTiAl alloy is C≤0.05%, Si≤0.4%, Mn≤0.4%, S≤0.010%, P≤0.015%, Cr 18-20%, Ti 2.7-3.2%, Al 1.3-1.8%, Co 5.5-6.7%, W 9.0-10.5%, Ce≤0.05%, B≤0.003%, Nb≤0.2%, V≤0.2%, Cu≤0.07%, Fe≤1.0%, and Ni is the balance.

[0024] The holding temperature, holding time and cooling mode of the first joint solid solution treatment in the process are "1160℃×1h holding, air cooling". The cooling mode is changed from water cooling to air cooling, the cooling process is slowed down, the internal stress caused by the temperature difference between the inside and outside during the cooling process of the first joint solid solution treatment is reduced, and the cracks caused by the too large internal stress are eliminated. However, the cooling speed during the air cooling process is slow, the alloy cannot quickly pass through the aging temperature interval of 650-820℃, and the partial aging effect is generated during the cooling process when the alloy is in the aging temperature interval. In addition, the slow cooling process generates more curved grain boundaries, which leads to the obvious increase of the strength (qualified) and the obvious decrease of the plasticity (unqualified). Through the first joint solid solution treatment, the primary internal crack problem is eliminated, although the performance is not completely qualified, the high strength and the low plasticity are relatively easy to solve, which lays a foundation for the final performance qualification by using the second joint solid solution treatment to slightly reduce the strength and obviously improve the plasticity to correct the performance.

[0025] The holding temperature, holding time and cooling mode of the second joint solid solution treatment are "1080℃×1h holding, water cooling". The second joint solid solution treatment can withstand greater internal stress on the basis of the high strength after the first joint solid solution treatment. The holding temperature of the second joint solid solution treatment is 1080℃, which is lower than the holding temperature of 1160℃ that is prone to generate internal cracks, and the internal stress caused by the temperature difference between the inside and outside during the cooling process is reduced, so that the alloy will not generate internal cracks under the combined action of high strength and reduced internal stress. At the same time, through the second joint solid solution treatment, the holding temperature is low, the reducing effect on the high strength formed after the first joint solid solution treatment is small, the cooling mode is water cooling, the improving effect on the low plasticity formed after the first joint solid solution treatment is obvious, so that the final performance is easily qualified after the second joint solid solution treatment on the basis of the good performance laid by the first joint solid solution treatment, and there is no internal crack.

[0026] The process of the present application does not simply combine two single joint solid solution treatment processes together, but changes the cooling mode of the first joint solid solution treatment to air cooling, keeps the cooling mode of the second joint solid solution treatment as water cooling, and then combines the two joints together, comprehensively utilizes the beneficial effects of each joint solid solution treatment on the alloy material, matches the two joints, realizes the best solid solution treatment effect, does not generate internal cracks, stably realizes the final performance requirements (mainly the mechanical performance requirements such as tensile performance, impact performance, hardness, etc.), and the solid solution treatment qualification rate is improved to 100%, solving the problems of the previous two single joint solid solution treatment processes that are prone to generate internal cracks and the final performance is unqualified.

[0027] The main feature comparison of the process of the present application and the previous solid solution treatment process is shown in Table 1.

[0028] Table 1 Main feature comparison of the process of the present application and the previous solid solution treatment process

[0029]

[0030] Advantages of the present application

[0031] Therefore, the double solid solution treatment process of the present application can avoid the internal cracks in the production process of the high crack-prone 68NiCrWCoTiAl alloy material, and stably achieve the final performance requirements, the solid solution treatment qualified rate reaches 100%, the serious uncertainty of the product quality and the serious quality risk are eliminated, the product yield and quality are both guaranteed, and a perfect solution for the normal manufacturing of the alloy material is provided, which has the advantages of high feasibility, reliability, product yield and quality.

[0032] The process of the present application is suitable for batch production of products.

[0033] The applicant's implementation shows that the 68NiCrWCoTiAl alloy material does not produce internal cracks, and the quality qualified rate is 100% by using the process of the present application; the tensile strength of the alloy bar is 1360.4-1369.4 MPa, the yield strength is 876.9-898.4 MPa, the elongation is 23-23.5%, the reduction of area is 27-29%, the impact toughness (U-shaped notch) is 45-50 J / cm 2 , the Brinell hardness HBW10 / 3000 is 345-362, which meets the requirements, and the final performance qualified rate is 100%; the comprehensive qualified rate is 100%, which can completely meet the research and production requirements, and the effect is very good. DETAILED DESCRIPTION

[0034] The heat treatment furnace of the process of the present application uses an electric heating heat treatment furnace, and the specific steps are as follows:

[0035] 1) First solid solution treatment

[0036] S1, the material to be treated is loaded into the heat treatment furnace when the furnace temperature is ≤100℃; the loading position is in the effective working area (uniform temperature area) of the heat treatment furnace; a 30-50mm high iron pad is placed under the material to be treated to prevent the material to be treated from directly contacting or approaching the heat generating body of the heat treatment furnace bottom plate to produce local overheating;

[0037] S2, the furnace temperature of the heat treatment furnace is raised to the holding temperature 1160±5℃, and is held for 1h; the temperature rising speed is 280±30℃ / h;

[0038] S3, the material to be treated is unloaded, and is naturally cooled to room temperature-100℃ in the air;

[0039] 2) Second solid solution treatment

[0040] S4, the first solid solution treatment of the to-be-treated material is loaded into the heat treatment furnace when the furnace temperature is ≤100℃; the loading position is in the effective working area (uniform temperature area) of the heat treatment furnace; a 30-50mm high iron pad is placed under the to-be-treated material to prevent the to-be-treated material from directly contacting or approaching the heat generating body at the bottom of the heat treatment furnace to cause local overheating;

[0041] S5, the furnace temperature of the heat treatment furnace is increased to the holding temperature 1080±5℃, and the holding time is 1h; the temperature increasing speed is 280±30℃ / h;

[0042] S6, the to-be-treated material is unloaded and rapidly placed into water for water cooling within ≤90s; the cooling water temperature is ≤30℃ when the to-be-treated material is placed into water, and the cooling water temperature should be ≤35℃ after the to-be-treated material is cooled; the cooling water keeps flowing.

[0043] The furnace temperature of the heat treatment furnace should be detected for uniformity, and the furnace temperature deviation and the furnace temperature uniformity should meet the requirement of ±10℃. Example 1

[0044] According to the process described in the application, the 68NiCrWCoTiAl alloy rod material with a diameter of φ30mm is subjected to solid solution treatment, and the alloy material does not produce internal cracks, and the quality qualified rate is 100%; the tensile strength of the alloy rod material is 1369.4MPa, the yield strength is 876.9MPa, the elongation is 23.5%, the reduction of area is 29%, the impact toughness (U-shaped notch) is 45 J / cm 2 , the Brinell hardness HBW10 / 3000 is 345, which meets the requirements, and the final performance qualified rate is 100%; the comprehensive qualified rate is 100%, which completely meets the scientific research and production requirements, and the effect is very good. Example 2

[0045] According to the process described in the application, the 68NiCrWCoTiAl alloy straight bar material with a diameter of φ16mm is subjected to solid solution treatment, and the alloy material does not produce internal cracks, and the quality qualified rate is 100%; the tensile strength of the alloy straight bar material is 1360.4MPa, the yield strength is 898.4MPa, the elongation is 23%, the reduction of area is 27%, the impact toughness (U-shaped notch) is 50 J / cm 2 , the Brinell hardness HBW10 / 3000 is 362, which meets the requirements, and the final performance qualified rate is 100%; the comprehensive qualified rate is 100%, which completely meets the scientific research and production requirements, and the effect is very good.

Claims

1. A duplex solution treatment process of 68NiCrWCoTiAl alloy, characterized by, It comprises the following steps: 1) first joint solid solution treatment S1, the furnace temperature of the heat treatment furnace is ≤100℃ when the material to be treated is loaded; the loading position is in the effective working area of the heat treatment furnace; S2, the furnace temperature of the heat treatment furnace is raised to the holding temperature of 1160±5℃, and is held for 1h; S3, the material to be treated is unloaded, and is naturally cooled to room temperature~100℃ in the air; 2) second joint solid solution treatment S4, the material to be treated after the first joint solid solution treatment is loaded into the heat treatment furnace when the furnace temperature is ≤100℃; the loading position is in the effective working area of the heat treatment furnace; S5, the furnace temperature of the heat treatment furnace is raised to the holding temperature of 1080±5℃, and is held for 1h; S6, the material to be treated is unloaded, and is rapidly placed into water for water cooling within ≤90 seconds; The temperature rising speed of the furnace temperature of the heat treatment furnace in steps S2 and S5 to the holding temperature is 280±30℃ / h; The mass percentage of each component of the 68NiCrWCoTiAl alloy is C≤0.05%, Si≤0.4%, Mn≤0.4%, S≤0.010%, P≤0.015%, Cr 18~20%, Ti 2.7~3.2%, Al 1.3~1.8%, Co 5.5~6.7%, W 9.0~10.5%, Ce≤0.05%, B≤0.003%, Nb≤0.2%, V≤0.2%, Cu≤0.07%, Fe≤1.0%, and Ni is the balance.

2. The duplex solutionizing process of claim 1, wherein: The heat treatment furnace in steps S1 and S4 is an electric heating heat treatment furnace.

3. The duplex solutionizing process of claim 1, wherein: The effective working area in steps S1 and S4 is a uniform temperature zone.

4. The duplex solutionizing process of claim 1, wherein: The furnace temperature of the heat treatment furnace in steps S1 and S4 should be detected for uniformity, and the deviation and uniformity should meet the requirement of ±10℃.

5. The duplex solutionizing process of claim 1, wherein: In steps S1 and S4, a 30~50mm high iron pad should be placed under the material to be treated.

6. The duplex solutionizing process of claim 1, wherein: In step S6, the time from unloading to water entering should be ≤90 seconds, and the cooling water should be kept flowing.

7. The duplex solutionizing process of claim 1, wherein: In step S6, the cooling water temperature is ≤30℃ when the material to be treated is rapidly placed into water for water cooling, and the cooling water temperature should be ≤35℃ after the material to be treated is cooled.

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