Production method of high-quality nickel for aviation-grade nickel-based superalloy

Abstract

The invention relates to the technical field of metallurgical industry, in particular to a production method of high-quality nickel for aviation-grade nickel-based superalloy, which comprises the following steps: pretreating raw materials; wherein the raw material is Ni9920 electrolytic nickel; carrying out vacuum induction melting on the pretreated raw materials, carrying out primary degassing and impurity removal, and casting an electrode bar; carrying out vacuum consumable remelting secondary impurity removal on the cast electrode bar to form a cast bar; performing plasma remelting on the casting rod for three times of deep impurity removal; according to the method, Ni9920 electrolytic nickel is used as a raw material, after the raw material is pretreated, a triple impurity removal process is carried out through vacuum induction melting, vacuum consumable remelting, plasma remelting and the like, the whole production process is carried out in a vacuum or argon filling state, impurity elements in the electrolytic nickel are deeply removed, and the quality of the electrolytic nickel is improved. The content of impurity elements in the electrolytic nickel is reduced to the nickel standard for aerospace, and Ni9920 electrolytic nickel is used as the raw material, so that the production cost is low, and the profit margin of high-quality nickel is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical industry, and in particular to a method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloys. Background Art

[0002] Nickel-based high-temperature alloy materials are important raw materials for the manufacture of aerospace engines. They are mainly used in engine combustion chambers, guide vanes, turbine blades, turbine discs, tail nozzles, casings and other components. The quality and performance of high-temperature alloys directly affect or even determine the performance of advanced equipment such as aerospace, ships, and electric power. With the rapid development of my country's aerospace, nuclear power and other fields in recent years, the market demand for high-temperature alloys has also continued to increase, driving the growth of my country's high-temperature alloy production. However, raw materials are the basis of high-temperature alloy master alloys, and their quality has an important influence on the quality of high-temperature alloys. In the high-temperature alloy market, nickel-based high-temperature alloys account for about 80%. Nickel is the main component of high-temperature alloys, and its content and purity have an important influence on the corrosion resistance, high-temperature strength and oxidation resistance of high-temperature alloys. In addition, the presence of impurities will have a negative impact on the performance of high-temperature alloys, so it is necessary to strictly control the impurity content of nickel raw materials.

[0003] Electrolytic nickel is divided into five grades according to the impurity content: Ni9999, Ni9996, Ni9990, Ni9950, and Ni9920. There is a gap between electrolytic nickel products and the demand in high-end fields such as aerospace. When comparing electrolytic nickel with the nickel standard for aerospace, the main elements that exceed the standard are Pb, Zn, As, Sb, Bi, Se, Te, O, and N.

[0004] Most of the smelting methods of pure nickel use vacuum induction melting (VIM), vacuum consumable melting (VAR), vacuum induction plus vacuum consumable double vacuum melting (VIM+VAR), vacuum induction plus electroslag melting duplex method (VIM+ESR), etc. There are also a small number of demanding industries such as military products that use (VIM+ESR+VAR) for production. The quality of pure nickel produced by the double vacuum melting (VIM+VAR) method is greatly improved compared to that of VIM ingots, but it still cannot effectively eliminate non-metallic inclusions and subcutaneous pores. Therefore, in order to ensure the quality of metallurgy, high requirements are placed on raw materials, and high-level clean raw materials such as electrolytic nickel and pure blocks are required, resulting in high costs.

[0005] 9920 electrolytic nickel is a product formed by using nickel anode plates to wrap the cut nickel ears, edge strips with nickel ears, nickel scraps, etc. with steel strips. Not only does the chemical composition of 3# nickel differ from the aerospace nickel standard, but it is also difficult to use it directly in the production of nickel-based high-temperature alloys due to its irregular shape. The sales price of 3# nickel is 5,000 yuan / ton lower than that of Ni9996 electrolytic nickel. Using 3# nickel as a raw material for the production of high-quality nickel can reduce the production cost of high-quality nickel and increase the profit margin of high-quality nickel.

[0006] In response to the above problems, after experiments and production exploration, the triple impurity removal process of "vacuum induction melting + vacuum consumable remelting + plasma remelting" can be adopted. After the raw materials of 9920 electrolytic nickel are pretreated, vacuum induction melting is carried out for degassing and impurities removal, vacuum consumable melting is carried out for degassing and impurities removal, and plasma remelting is carried out for deep impurities removal. The production can meet the requirements of high-quality nickel raw materials and meet the index requirements of aviation-grade high-quality nickel (Q / 6S 4344-2022). Summary of the invention

[0007] The present invention provides a method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloys, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problem of high production cost of existing high-quality nickel.

[0008] To solve the above problems, the present invention provides a method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloys, comprising the following steps: Pre-treating the raw materials; wherein the raw materials are Ni9920 electrolytic nickel; The pre-treated raw materials are subjected to vacuum induction melting to remove gas and impurities, and electrode rods are cast; The cast electrode rod is subjected to vacuum consumable remelting for secondary impurity removal to form a cast rod; The cast rods are plasma remelted three times to remove impurities and produce high-quality nickel rods.

[0009] The above-mentioned pretreatment of raw materials includes: The raw material Ni9920 electrolytic nickel is sheared into small pieces of less than 100 mm by a shearing machine; Use a rust-removing ball mill to clean the surface of small pieces of raw materials; The polished raw materials are washed with deionized water and then blown dry with a blower; The dried raw materials were placed in a trolley resistance furnace and baked at 200°C for 2h in a slightly positive pressure atmosphere filled with argon.

[0010] The above-mentioned vacuum induction melting and impurity removal of the pretreated raw materials and casting of electrode rods include: The pretreated raw material Ni9920 electrolytic nickel is placed in a crucible of a vacuum induction furnace; Add carbon powder with a particle size of 10-30 mm to the lower part of the crucible, and the amount of carbon powder added is 0.01% of the mass of Ni9920 electrolytic nickel; After the vacuum degree in the vacuum induction furnace is evacuated to 2Pa, the vacuum induction furnace is powered on and heated up. The power is increased by 15KW every 20 minutes, so that the Ni9920 electrolytic nickel is degassed for the second time under the high vacuum and high temperature conditions of the vacuum induction furnace. All the materials in the vacuum induction furnace are melted, and the vacuum degree reaches 5×10 -2 Pa, high temperature refining starts when the temperature is controlled at 1550℃, and Pb, Zn, As, Sb, Bi, Se, Te, O, and N gradually begin to volatilize and decrease as stirring proceeds; After 20 minutes of high-temperature refining, the vacuum induction furnace is powered off for freezing treatment. After the surface is filmed, power is supplied to shake the grate to remove slag. When the surface of the molten steel is clear and free of impurities, steel is cast to cast multiple Φ50×475mm electrode rods.

[0011] The above-mentioned vacuum consumable remelting of the cast electrode rod comprises: Place the electrode rod into a vacuum consumable furnace and pump the vacuum degree in the vacuum consumable furnace to 2×10 -2 Pa, set the melting current to 3KA, the arc voltage to 3V for consumable melting, the melting vacuum to 1Pa, and after the melting is completed and the cooling time is 40min, the ingot is taken out of the air, and the ingot specification is Φ70×400mm cast rod.

[0012] The above three-step deep impurity removal of the cast rod by plasma remelting includes: The cast rod is placed in a plasma remelting furnace, and the plasma remelting furnace is evacuated to 2×10 -2 Pa, maintain stability and continue to fill with argon to 350Pa, set the main arc current to 700-1000A, the maintenance arc current to 100A, perform plasma remelting, use a high-strength water-cooled copper crystallizer to solidify and crystallize the molten steel, and take out the cast rod after cooling for 1h. The ingot specification is Φ70×400mm cast rod.

[0013] The present invention uses Ni9920 electrolytic nickel as a raw material, performs a triple impurity removal process on the raw material after pretreatment, and then performs vacuum induction melting, vacuum consumable remelting, plasma remelting and the like. The entire production process is carried out in a vacuum or argon-filled state without being polluted by external air, and impurity elements such as Pb, Zn, As, Sb, Bi, Se, Te, O, and N in the electrolytic nickel are deeply removed to prepare high-quality nickel raw materials, and the content of impurity elements in the electrolytic nickel is reduced to the standard of nickel for aerospace use, thereby providing high-quality raw materials for nickel for high-end nickel-based high-temperature alloys. In addition, the use of Ni9920 electrolytic nickel as a raw material has low production cost and a simple production method, thereby increasing the profit margin of high-quality nickel. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0015] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0016] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0017] like Figure 1 As shown, the embodiment of the present invention discloses a method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloys, comprising the following steps: Pre-treating the raw materials; wherein the raw materials are Ni9920 electrolytic nickel; The pre-treated raw materials are subjected to vacuum induction melting to remove gas and impurities, and electrode rods are cast; The cast electrode rod is subjected to vacuum consumable remelting for secondary impurity removal to form a cast rod; The cast rods are plasma remelted three times to remove impurities and produce high-quality nickel rods.

[0018] Among them, the raw materials are pretreated, including: The raw material Ni9920 electrolytic nickel is sheared into small pieces <100mm by a shearing machine; (the raw material cost of Ni9920 electrolytic nickel is 5,000 yuan / ton lower than that of Ni9926 electrolytic nickel, the production raw material cost is low, and the enterprise profit margin is large) Use a rust-removing ball mill to clean the surface of small pieces of raw materials; remove surface stains, oxide films and nitride films; The polished raw materials are washed with deionized water and then blown dry with a blower; The dried raw materials are placed in a trolley resistance furnace and baked at 200°C for 2h in a slightly positive pressure atmosphere filled with argon to remove moisture and part of the gas on the surface of Ni9920 electrolytic nickel.

[0019] According to the difference between the pure element vapor pressure of various impurities in electro-nickel and the vapor pressure of the main element Ni, the vapor pressure of elements As to Sn gradually decreases, among which the vapor pressure of As, Sb, Cd, Tl, Te, Mg, Bi, Se, and Pb is higher than that of Ni. Therefore, it is highly possible to remove Pb, Zn, As, Sb, Bi, Se, Te, O, and N under vacuum. Vacuum induction melting is used for one-time impurity removal, specifically: The pre-treated raw materials are vacuum induction melted to remove impurities and cast electrode rods, including: The pretreated raw material Ni9920 electrolytic nickel is placed in the crucible of the vacuum induction furnace; the crucible is made of alumina crucible, and the filter is a 15PPI zirconium oxide filter; Add carbon powder with a particle size of 10-30 mm to the lower part of the crucible. The amount of carbon powder added is 0.01% of the mass of Ni9920 electrolytic nickel. The purpose of adding carbon powder is deoxidation. After the vacuum degree in the vacuum induction furnace is evacuated to 2Pa, the vacuum induction furnace is powered on and heated up. The power is increased by 15KW every 20 minutes, so that the Ni9920 electrolytic nickel is degassed for the second time under the high vacuum and high temperature conditions of the vacuum induction furnace. All the materials in the vacuum induction furnace are melted, and the vacuum degree reaches 5×10 -2 Pa, high-temperature refining begins when the temperature is controlled at 1550℃, and Pb, Zn, As, Sb, Bi, Se, Te, O, and N gradually begin to volatilize and decrease as the stirring proceeds; wherein, a vacuum unit is used to evacuate the vacuum induction furnace; using the high vacuum and high temperature conditions, the electromagnetic stirring of the molten steel in the vacuum induction furnace is used to further remove the gas and low-melting-point impurities in the molten steel.

[0020] After 20 minutes of high-temperature refining, the vacuum induction furnace is powered off for freezing treatment. After the surface is filmed, power is supplied to shake the grate to remove slag. When the surface of the molten steel is clear and free of impurities, steel is tapped and electrode rods are cast. The temperature is controlled at 1480-1500℃ for tapping and casting. After 10 minutes of tapping, the vacuum is broken to cast multiple Φ50×475mm cast rods.

[0021] After vacuum induction melting, the cast rod is cut off from the riser and used as a vacuum consumable electrode, and the vacuum consumable electrode is used for secondary impurity removal. A part of the gas impurities are removed through the low-voltage and high-current vacuum consumable melting process, and the molten steel is solidified and crystallized using a high-strength water-cooled copper crystallizer to obtain a uniform, shrinkage-free and dense steel ingot. As some non-metallic inclusions in the consumable electrode, such as oxides and nitrides, are dissociated or reduced by carbon under vacuum and high temperature conditions and removed, the purpose of further purification is achieved; specifically: the cast electrode rod is remelted by vacuum consumable melting, including: Place the electrode rod into a vacuum consumable furnace and pump the vacuum degree in the vacuum consumable furnace to 2×10 -2 Pa, set the melting current to 3KA, the arc voltage to 3V for consumable melting, the melting vacuum to 1Pa, and take out the ingot after 40min of cooling after melting. The ingot specification is Φ70×400mm casting rod. Among them, the vacuum unit is used to evacuate the vacuum consumable furnace.

[0022] After vacuum consumable melting, the Φ70×400mm cast rod is subjected to three times of impurity removal and high purification through plasma arc remelting. The plasma arc remelting process is mainly based on the ultra-high temperature of plasma and can effectively control the atmosphere in the furnace according to different needs to achieve degassing, volatilization of metal impurities, and removal of non-metallic inclusions to achieve the purpose of nickel purification; specifically: the cast rod is subjected to three times of deep impurity removal by plasma remelting, including: The cast rod is placed in a plasma remelting furnace, and the plasma remelting furnace is evacuated to 2×10 -2 Pa, maintain stability and continue to fill with argon to 350Pa, set the main arc current to 700-1000A, the maintenance arc current to 100A, perform plasma remelting, use a high-strength water-cooled copper crystallizer to solidify and crystallize the molten steel, and take out the cast rod after cooling for 1h. The ingot specification is Φ70×400mm cast rod.

[0023] In summary, the present invention uses Ni9920 electrolytic nickel as a raw material, and after pre-treating the raw material, performs a triple impurity removal process through vacuum induction melting, vacuum consumable remelting, plasma remelting, etc. The entire production process is carried out in a vacuum or argon-filled state without being polluted by the outside air, and the impurity elements such as Pb, Zn, As, Sb, Bi, Se, Te, O, and N in the electrolytic nickel are deeply removed to prepare high-quality nickel raw materials, and the content of impurity elements in the electrolytic nickel is reduced to the standard of nickel for aerospace, providing high-quality raw materials for nickel for high-end nickel-based high-temperature alloys, and using Ni9920 electrolytic nickel as a raw material, the production cost is low, the production method is simple, and the profit margin of high-quality nickel is increased.

Claims

1. A method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloys, characterized in that: The following steps are involved: Pre-treating the raw materials; wherein the raw materials are Ni9920 electrolytic nickel; The pre-treated raw materials are subjected to vacuum induction melting to remove gas and impurities, and electrode rods are cast; The cast electrode rod is subjected to vacuum consumable remelting for secondary impurity removal to form a cast rod; The cast rods are plasma remelted three times to remove impurities and produce high-quality nickel rods.

2. The method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloy according to claim 1, characterized in that: The pretreatment of the raw materials comprises: The raw material Ni9920 electrolytic nickel is sheared into small pieces of less than 100 mm by a shearing machine; Use a rust-removing ball mill to clean the surface of small pieces of raw materials; The polished raw materials are washed with deionized water and then blown dry with a blower; The dried raw materials were placed in a trolley resistance furnace and baked at 200°C for 2h in a slightly positive pressure atmosphere filled with argon.

3. The method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloy according to claim 1, characterized in that: The method of vacuum induction melting and impurity removal of the pretreated raw materials and casting electrode rods comprises: The pretreated raw material Ni9920 electrolytic nickel is placed in a crucible of a vacuum induction furnace; Add carbon powder with a particle size of 10-30 mm to the lower part of the crucible, and the amount of carbon powder added is 0.01% of the mass of Ni9920 electrolytic nickel; After the vacuum degree in the vacuum induction furnace is evacuated to 2Pa, the vacuum induction furnace is powered on and heated up. The power is increased by 15KW every 20 minutes, so that the Ni9920 electrolytic nickel is degassed for the second time under the high vacuum and high temperature conditions of the vacuum induction furnace. All the materials in the vacuum induction furnace are melted, and the vacuum degree reaches 5×10 -2 Pa, high temperature refining starts when the temperature is controlled at 1550℃, and Pb, Zn, As, Sb, Bi, Se, Te, O, and N gradually begin to volatilize and decrease as stirring proceeds; After 20 minutes of high-temperature refining, the vacuum induction furnace is powered off for freezing treatment. After the surface is filmed, power is supplied to shake the grate to remove slag. When the surface of the molten steel is clear and free of impurities, steel is cast to cast multiple Φ50×475mm electrode rods.

4. The method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloy according to claim 1, characterized in that: The method of vacuum consumable remelting the cast electrode rod comprises: Place the electrode rod into a vacuum consumable furnace and pump the vacuum degree in the vacuum consumable furnace to 2×10 -2 Pa, set the melting current to 3KA, the arc voltage to 3V for consumable melting, the melting vacuum degree to 1Pa, and after the melting is completed and the cooling time is 40min, the ingot is taken out of the air, and the ingot specification is Φ70×400mm cast rod.

5. The method for producing high-quality nickel for aviation-grade nickel-based high-temperature alloy according to claim 1, characterized in that: The plasma remelting of the cast rods for three times of deep impurity removal comprises: The cast rod is placed in a plasma remelting furnace, and the plasma remelting furnace is evacuated to 2×10 -2 Pa, maintain stability and continue to fill with argon to 350Pa, set the main arc current to 700-1000A, the maintenance arc current to 100A, perform plasma remelting, use a high-strength water-cooled copper crystallizer to solidify and crystallize the molten steel, and take out the cast rod after cooling for 1h. The ingot specification is Φ70×400mm cast rod.

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