Vacuum induction melting process for improving N element yield of cobalt-based high-temperature alloy

Abstract

The invention belongs to the technical field of alloy smelting, and particularly relates to a vacuum induction smelting process for improving the yield of the element N of a cobalt-based high-temperature alloy, which comprises the following steps of: putting an N raw material into a feeder which is made of a cobalt plate and has a regular shape, before the N raw material is added, reducing the smelting power to 50-350kW, controlling the melt temperature to 1500-1650 DEG C, refining for 10-50 minutes, and then, cooling to room temperature to obtain the N-based high-temperature alloy. And stopping the power until the liquid level of the melt forms a film, filling argon to 2.5-7.5 kPa 10-40 minutes before pouring, adding a feeder with an N raw material into the furnace through an upper feeding chamber, stirring for 5-15 minutes, increasing the power to 100-650 kW, controlling the temperature of the melt to be 1500-1600 DEG C, then pouring, controlling the pouring time to be 5-35 minutes, and completing the alloy smelting. According to the method, the yield of the element N in the cobalt-based high-temperature alloy can be increased, and the content of the element N in the high-temperature alloy can be accurately controlled.

Description

Technical Field

[0001] This invention belongs to the field of alloy melting technology, and particularly relates to a vacuum induction melting process for improving the nitrogen yield of cobalt-based superalloys. Background Technology

[0002] Cobalt-based superalloys are complex multi-component alloys with a high degree of alloying, exhibiting excellent high-temperature performance, good oxidation resistance, and resistance to gas corrosion. They are widely used in the manufacture of hot-end components such as turbine guide vanes for gas turbine engines. Adding nitrogen (N) to cobalt-based superalloys can improve their hardness and wear resistance, enhance corrosion resistance, reduce the release of metal ions, and improve biocompatibility. However, excessively high N content can have many negative effects. When melting superalloys in a vacuum induction furnace, N is prone to volatilization, resulting in low yields and difficulties in controlling its content. These challenges urgently need to be addressed to produce alloy products that meet the required composition.

[0003] Therefore, in order to improve the gas element recovery rate during vacuum induction melting of high-temperature alloys, especially for high-temperature alloys with strict requirements on the content range of nitrogen element, it is of great engineering significance to develop a reasonable nitrogen element feeding method and a corresponding vacuum induction melting process. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a vacuum induction melting process for improving the nitrogen (N) yield in cobalt-based superalloys. This invention can increase the N yield to over 80% during superalloy melting, ensuring uniform distribution, while also producing a high-purity master alloy. This process is suitable for superalloy production where strict control of N content is required.

[0005] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows: This invention provides a vacuum induction melting process for improving the nitrogen yield of cobalt-based superalloys, comprising the following steps: (1) Weigh the raw materials according to the weight of N required for alloy smelting; (2) Place the N raw material into the feeder and perform welding and sealing treatment; (3) Before adding raw material N, the melting power of the vacuum induction melting furnace is reduced to 50-350kW, the temperature of the alloy liquid is controlled at 1500-1650℃, and the refining time is 10-50min; (4) After refining, stop the power and cool down until the alloy liquid forms a film. 10 to 40 minutes before pouring the alloy liquid, fill the vacuum induction furnace with argon gas to 2.5 to 7.5 kPa and maintain the argon atmosphere until the pouring is finished. Then add the feeder containing the N raw material into the crucible. (5) After the N raw material is added, stir for 5 to 15 minutes, increase the power to 100 to 650 kW, control the melt temperature to 1500 to 1600 ℃ and then pour it. The pouring time is controlled at 5 to 35 minutes to complete the cobalt-based high-temperature alloy smelting.

[0006] Further, in step (1), the N raw material is a chromium nitride alloy, and the N element weight percentage in the chromium nitride alloy is 10 to 30 wt%.

[0007] Furthermore, the feeder is a regularly shaped container made of raw material cobalt.

[0008] Furthermore, the feeder is a spherical container cast from raw material cobalt.

[0009] Furthermore, the feeder is a triangular container made of cobalt plates.

[0010] Furthermore, the feeder is a quadrilateral container made of cobalt plates.

[0011] Furthermore, the cobalt-based superalloy contains molybdenum.

[0012] Furthermore, the feeder is a regularly shaped container made of raw material molybdenum.

[0013] The beneficial effects of the technical solutions provided in the embodiments of the present invention are as follows: (1) By using the N element feeding method and vacuum induction melting process of the present invention, the N element content can be effectively and accurately controlled within the range of 0.02 to 0.25 wt%.

[0014] (2) By adopting the N element feeding method and vacuum induction melting process of the present invention, the N element yield is greatly improved, and the N yield is increased to more than 80%.

[0015] (3) This invention enables stable control of N element yield, avoids product scrapping due to unqualified N element chemical composition, and has significant economic benefits. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, a Co-Cr-Mo high-temperature alloy is used as an example to further illustrate the invention. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0017] Example 1 A vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys, with a single furnace melting weight of 2000 kg of alloy, includes the following steps: (1) Weigh chromium nitride raw materials with a nitrogen content of 10 wt% according to the nitrogen content requirements in Co-Cr-Mo high-temperature alloy; (2) Place the weighed N raw material into a triangular feeder welded from cobalt plates; (3) Before feeding N raw materials, the melting power of the vacuum induction melting furnace is reduced to 200kW, the temperature of the alloy liquid is controlled at 1580℃, and the refining time is 40min; (4) After refining, stop the power and cool down until the alloy liquid forms a film. 40 minutes before pouring the alloy liquid, fill the vacuum induction furnace with argon gas to 4 kPa and add the feeder with N raw materials into the crucible. (5) After adding raw material N, stir for 10 minutes, increase the power to 400kW, control the melt temperature to 1540℃ and prepare for casting. The alloy liquid is poured into the casting rod mold tube, and the casting time is controlled at 15 minutes to complete the alloy melting and casting.

[0018] Example 2 A vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys, with a single furnace melting weight of 2000 kg of alloy, includes the following steps: (1) Weigh chromium nitride raw materials with a N content of 20 wt% according to the N content requirements in Co-Cr-Mo high-temperature alloy; (2) Place the weighed N raw material into the spherical feeder cast from cobalt plate; (3) Before feeding N raw materials, the melting power of the vacuum induction melting furnace is reduced to 120kW, the temperature of the alloy liquid is controlled at 1620℃, and the refining is carried out for 20 minutes. (4) After refining, stop the power and cool down until the alloy liquid forms a film. 25 minutes before pouring the alloy liquid, fill the vacuum induction furnace with argon gas to 5 kPa and add the feeder with N raw materials into the crucible. (5) After adding raw material N, stir for 5 minutes, increase the power to 400kW, control the melt temperature to 1560℃ and prepare for casting. The alloy liquid is poured into the casting rod mold tube, and the casting time is controlled at 18 minutes to complete the alloy melting and casting.

[0019] Example 3 A vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys, with a single furnace melting weight of 2000 kg of alloy, includes the following steps: (1) Weigh chromium nitride raw materials with a N content of 30 wt% according to the N content requirements in Co-Cr-Mo high-temperature alloy; (2) Place the weighed N raw material into the quadrilateral feeder welded with cobalt plate; (3) Before feeding N raw materials, the melting power of the vacuum induction melting furnace is reduced to 150kW, the temperature of the alloy liquid is controlled at 1630℃, and the refining is carried out for 30 minutes. (4) After refining, stop the power and cool down until the alloy liquid forms a film. 30 minutes before pouring the alloy liquid, fill the vacuum induction furnace with argon gas to 7.5 kPa and add the feeder with N raw materials into the crucible. (5) After adding raw material N, stir for 5 minutes, increase the power to 500kW, control the melt temperature to 1580℃ and prepare for casting. The alloy liquid is poured into the casting rod mold tube, and the casting time is controlled at 20 minutes to complete the alloy melting and casting.

[0020] Comparative Example 1 Raw material N was directly fed into the furnace, and other conditions were the same as in Example 1.

[0021] Comparative Example 2 Raw material N was directly fed into the furnace, and other conditions were the same as in Example 2.

[0022] Comparative Example 3 Raw material N was directly fed into the furnace, and other conditions were the same as in Example 3.

[0023] In Examples 1-3 and Comparative Examples 1-3, the nitrogen (N) content was 0.11 wt% during the smelting of the high-temperature alloy master alloys. Samples were taken from different locations of the master alloys smelted in Examples 1-3 and Comparative Examples 1-3 for N chemical composition analysis, and the N yield was calculated. The results are shown in Table 1. Table 1. Nitrogen content (wt%) and yield (%) in Examples 1-3 and Comparative Examples 1-3

[0024] As shown in Table 1, the nitrogen (N) yield of the three furnaces of Co-Cr-Mo high-temperature alloy master alloys smelted using the technical solution of this invention is as high as 80% or more. This indicates that this invention can significantly improve the N yield while ensuring uniform composition throughout the furnace.

[0025] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys, characterized in that, Includes the following steps: (1) Weigh the raw materials according to the weight of N required for alloy smelting; (2) Place the N raw material into the feeder and perform welding and sealing treatment; (3) Before adding raw material N, the melting power of the vacuum induction melting furnace is reduced to 50-350kW, the temperature of the alloy liquid is controlled at 1500-1650℃, and the refining time is 10-50min; (4) After refining, stop the power and cool down until the alloy liquid forms a film. 10 to 40 minutes before pouring the alloy liquid, fill the vacuum induction furnace with argon gas to 2.5 to 7.5 kPa and maintain the argon atmosphere until the pouring is finished. Then add the feeder containing the N raw material into the crucible. (5) After the N raw material is added, stir for 5 to 15 minutes, increase the power to 100 to 650 kW, control the melt temperature to 1500 to 1600 ℃ and then pour it. The pouring time is controlled at 5 to 35 minutes to complete the cobalt-based high-temperature alloy smelting.

2. The vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys according to claim 1, characterized in that, In step (1), the N raw material is a chromium nitride alloy, and the N element weight percentage in the chromium nitride alloy is 10 to 30 wt%.

3. The vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys according to claim 1, characterized in that, The feeder is a regularly shaped container made of raw material cobalt.

4. The vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys according to claim 1, characterized in that, The feeder is a spherical container cast from raw material cobalt.

5. The vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys according to claim 1, characterized in that, The feeder is a triangular container made of cobalt plates.

6. The vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys according to claim 1, characterized in that, The feeder is a quadrilateral container made of cobalt plates.

7. The vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys according to claim 1, characterized in that, The cobalt-based superalloy contains molybdenum.

8. The vacuum induction melting process for improving nitrogen yield in cobalt-based superalloys according to claim 7, characterized in that, The feeder is a regularly shaped container made of raw material molybdenum.

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