Method for controlling magnesium content in high-temperature alloy

Abstract

The invention discloses a method for controlling the content of magnesium in a high-temperature alloy, and belongs to the technical field of special metallurgy. The scheme comprises the following steps: performing vacuum induction melting on each raw material according to the component requirements of the smelted high-temperature alloy; niMg-MoO3-C-Mo composite alloy balls are added into the vacuum induction molten metal liquid, smelting continues to be carried out, and alloying treatment of Mg is carried out; the ratio of the density of the NiMg-MoO3-C-Mo composite alloy balls to the density of the molten metal is 1.05-1.10, the NiMg-MoO3-C-Mo composite alloy balls comprise inner-layer pellets and Mo powder wrapping the inner-layer pellets, and raw materials of the inner-layer pellets comprise MoO3, C and NiMg alloy; the molten metal subjected to Mg alloying treatment is poured into a consumable electrode; and the consumable electrode is subjected to electroslag remelting, so that an electroslag ingot is obtained. According to the scheme, the NiMg-MoO3-C-Mo composite alloy balls with the density larger than that of the high-temperature molten metal are put into the high-temperature molten alloy, and the yield of Mg in the smelting process is effectively increased.

Description

Technical Field

[0001] The invention relates to the technical field of special metallurgy, and more specifically to a method for controlling the magnesium content in a high-temperature alloy. Background Art

[0002] High-temperature alloys are a type of metal material that can work for a long time at temperatures above 600°C and under certain stresses. They have excellent high-temperature strength, good oxidation resistance and thermal corrosion resistance, fatigue resistance, fracture toughness and other comprehensive properties. In high-temperature alloys, especially nickel-based high-temperature alloys, adding trace amounts of magnesium can significantly improve the hot working plasticity of high-temperature alloys and significantly improve the high-temperature strength of alloys. Therefore, magnesium has become one of the important trace alloying elements in high-temperature alloys.

[0003] However, there are still difficulties in accurately controlling the magnesium content in high-temperature alloys. The key difficulty lies in the fact that magnesium has a high vapor pressure, low density, and is extremely easy to oxidize. Therefore, it is difficult to accurately control the magnesium content in high-temperature alloys to within the target range.

[0004] After searching, the Chinese invention patent with application number 201310443962X discloses a method for smelting a high-temperature alloy containing Mg. The application adopts vacuum induction plus electroslag remelting. During the vacuum induction smelting process, a nickel-magnesium alloy of 80% nickel and 20% magnesium is added into the furnace to increase the magnesium content of the high-temperature alloy. However, the density of the nickel-magnesium alloy of 80% nickel and 20% magnesium does not exceed 6g / cm 3 , while the density of high-temperature alloys is generally greater than 8g / cm 3 Therefore, the added nickel-magnesium alloy floats in the high-temperature alloy liquid. In addition, the high temperature and vacuum environment cause a large amount of nickel in the nickel-magnesium alloy to volatilize and cannot enter the metal liquid, which leads to a low magnesium yield. In addition, in the electroslag remelting process, the remelting slag system used contains only 5-10% MgO, which is similar to the traditional electroslag remelting slag system and cannot effectively inhibit the burning of magnesium.

[0005] The Chinese invention patent with application number 2023100518683 discloses a method for controlling the Mg content in the smelting process of nickel-based high-temperature alloys. The application also uses vacuum induction plus electroslag remelting. In the vacuum induction melting stage, a nickel-magnesium alloy containing 5-10% Mg is added for magnesium microalloying. However, the maximum density of the nickel-magnesium alloy containing 5-10% Mg will not exceed 7g / cm 3 , which is still lower than the density of high-temperature alloys, resulting in a low magnesium yield. In addition, the MgO content in the electroslag remelting process is still low, and magnesium is still burned during the remelting process.

[0006] The Chinese invention patent with application number 2020109727854 discloses a method for controlling the yield of magnesium in GH4141 high-temperature alloy, by adding a nickel-magnesium alloy wrapped in aluminum foil into a vacuum induction furnace. However, since the density of the nickel-magnesium alloy is lower than that of the GH4141 high-temperature alloy, the density of the aluminum foil is even lower, resulting in a further reduction in the density of the nickel-magnesium alloy wrapped in aluminum foil. When added to the induction furnace, it floats on the surface of the molten metal; the melting point of the aluminum foil is less than 700°C, which is much lower than the temperature of the high-temperature alloy liquid, and it melts quickly, causing the nickel-magnesium alloy to be exposed and volatilized, and its yield is reduced.

[0007] The Chinese invention patent with application number 2016109923849 discloses a method for controlling the magnesium content in a nickel-based high-temperature alloy during vacuum induction smelting. The method also adds a nickel-magnesium alloy with a lower density into the induction furnace, but there are still problems of nickel volatilization and low magnesium yield.

[0008] The Chinese invention patent with application number 2023100560110 discloses a method for producing high-temperature bearing steel by magnesium treatment, which increases the magnesium content of the molten steel by feeding magnesium wire into the electroslag remelting process. However, the boiling point of magnesium is only 1107°C, while the melting point of the slag pool in the electroslag remelting process is greater than 1700°C. When adding magnesium to the molten steel, the magnesium wire must first pass through the high-temperature slag pool, which will cause the magnesium wire to volatilize violently, thereby reducing the stability of the magnesium yield.

[0009] The Chinese invention patent with application number 202310968378X discloses a method for treating magnesium in molten steel in coordination with electroslag remelting, which controls the electroslag composition to strengthen the slag-gold reaction and thus control the magnesium content in the steel. However, electroslag remelting lasts for a long time, up to dozens of hours at most. As the slag-gold reaction proceeds, the magnesium-containing compounds in the slag gradually decrease, causing the slag-gold reaction to gradually weaken and the magnesium content in the steel to gradually decrease. As a result, the longitudinal deviation of the magnesium content in the electroslag ingot is large, which leads to a large longitudinal performance deviation.

[0010] The Chinese invention patent with application number 2017101462317 discloses a method for improving the recovery rate of magnesium in molten steel, by adding Fe-Ni-Mg alloy into a pressurized induction furnace, so that the alloy enters deep into the molten steel, thereby improving the recovery rate of magnesium in the molten steel. However, due to the low boiling point and high vapor pressure of Mg, after the added magnesium-containing alloy enters deep into the molten steel, the alloy will instantly produce a large number of magnesium bubbles gathered together, which is very likely to cause the molten steel to splash; and because the gathered magnesium bubbles rise quickly, the contact time between the bubbles and the molten steel will be reduced, thereby reducing the recovery rate of magnesium. Although this patent has a certain increase in the recovery rate of magnesium compared with the traditional magnesium increase method, it still needs further optimization. In particular, in order to improve the recovery rate of magnesium, this patent introduces a pressure of 0.5 to 2MPa into the induction furnace. This pressure has extremely high requirements for vacuum induction equipment, especially the maximum pressure that can be introduced into the current mainstream vacuum induction furnace does not exceed 0.1MPa, which is much lower than the pressure required by this patent. Therefore, this patent still has great difficulties in increasing magnesium in traditional vacuum induction furnaces. Summary of the invention

[0011] In view of the technical problems of magnesium volatilization and low yield in the current high-temperature magnesium alloying process, the present invention provides a method for controlling the magnesium content in a high-temperature alloy. The solution can effectively improve the Mg yield in the smelting process by adding NiMg-MoO3-C-Mo composite alloy balls to the molten metal during the vacuum induction melting process.

[0012] The present invention provides a method for controlling the magnesium content in a high-temperature alloy, comprising: subjecting raw materials to vacuum induction melting according to the composition requirements of the smelted high-temperature alloy; adding NiMg-MoO3-C-Mo composite alloy balls to the vacuum induction molten metal liquid for continued smelting to perform Mg alloying treatment; the density of the NiMg-MoO3-C-Mo composite alloy balls is 1.05-1.10 to the density of the metal liquid, and the NiMg-MoO3-C-Mo composite alloy balls comprise inner layer pellets and Mo powder wrapped around the outer surface of the inner layer pellets, and the raw materials of the inner layer pellets comprise MoO3, C and NiMg alloy; casting the metal liquid after the Mg alloying treatment into a consumable electrode; and electroslag remelting the consumable electrode to obtain an electroslag ingot.

[0013] In view of the problem that magnesium is easy to volatilize and has a low yield when magnesium alloying is performed on high-temperature alloys in the prior art, the present invention adds NiMg-MoO3-C-Mo composite alloy balls, thereby effectively avoiding the volatilization of magnesium and improving its yield. It should be noted that the density of the NiMg-MoO3-C-Mo composite alloy balls added by vacuum induction melting and their composition are very important in the present invention. Specifically, the density of the NiMg-MoO3-C-Mo composite alloy ball is 1.05-1.10 to the density of the high-temperature molten metal, that is, it is greater than the density of the high-temperature molten metal. After the alloy ball is added to the molten metal, it will sink to the bottom of the molten metal relatively quickly. Due to the high temperature of the molten metal, the MoO3 and C inside the composite alloy ball react rapidly to produce a certain amount of CO gas. Under the crushing action of the CO gas, the outer Mo wrapping layer is destroyed, so that the NiMg alloy is dispersed in the molten metal, avoiding the agglomeration of NiMg and preventing the problem of a large number of bubbles being generated instantly. Magnesium in NiMg alloy generates magnesium vapor under high temperature, which is absorbed by molten steel during the floating process to achieve the purpose of alloying. And because NiMg alloy is dispersed in molten steel, the generated magnesium vapor is also dispersed in the molten steel, which is conducive to the absorption of magnesium by the alloy liquid, thereby increasing the yield of magnesium. Specifically, the density of the alloy ball can be effectively controlled by controlling its compaction degree during the alloy ball forming process.

[0014] Furthermore, the addition amount of the NiMg-MoO3-C-Mo composite alloy ball accounts for 0.2-0.6% of the mass of the molten metal.

[0015] Furthermore, the mass ratio of C to MoO3 in the NiMg-MoO3-C-Mo composite alloy ball is 0.8-0.9:4.

[0016] Furthermore, the particles of the NiMg alloy in the inner layer of the NiMg-MoO3-C-Mo composite alloy ball are 2 to 5 mm. The NiMg alloy particles are preferably 2 to 5 mm, which further promotes the uniform dispersion of the NiMg alloy in the molten metal, avoiding the problem of NiMg agglomeration and the instantaneous generation of a large number of bubbles. Moreover, the generated magnesium vapor is also more dispersed in the molten steel, which is more conducive to the absorption of magnesium by the alloy liquid, thereby further improving the magnesium recovery rate.

[0017] Furthermore, the particles of MoO3 and C used in the inner layer pellets of the NiMg-MoO3-C-Mo composite alloy ball are 200 mesh to 250 mesh.

[0018] Furthermore, the particle size of the Mo powder is 50-100 meshes.

[0019] Furthermore, the diameter of the NiMg-MoO3-C-Mo composite alloy ball is 30-40 mm, and the diameter of the inner layer pellet is 20-25 mm. MoO3 and C are first mixed, and then the mixture of MoO3 and C and NiMg particles are mixed to form the inner layer pellet, and finally Mo powder is coated on the outer surface of the inner layer pellet.

[0020] Furthermore, argon gas is introduced into the vacuum chamber, and when the pressure of the vacuum chamber reaches 20000-30000 Pa, NiMg-MoO3-C-Mo composite alloy balls are added into the vacuum induction molten metal liquid.

[0021] Furthermore, after adding NiMg-MoO3-C-Mo composite alloy balls into the vacuum induction molten metal, the alloy liquid is first allowed to stand for 3 to 5 minutes, and then induction heating is started. After the temperature rises to 1450 to 1500°C, heating is stopped, electromagnetic stirring is started for 1 minute, and finally the metal consumable electrode is cast.

[0022] Furthermore, 10 to 15 minutes before the end of refining, 0.4 to 4.0% Al and 1.0 to 3.0% Ti by mass are added to the vacuum induction molten metal; electromagnetic stirring is performed for 1 to 3 minutes, and then induction heating is started to keep the temperature between 1450 and 1460°C; and then NiMg-MoO3-C-Mo composite alloy balls are added to the vacuum induction molten metal.

[0023] Furthermore, the temperature of the vacuum induction refining is 1450-1500° C., the refining time is 2-10 hours, and the vacuum degree is ≤2Pa.

[0024] Furthermore, during the electroslag remelting of the consumable electrode, NiMg-MoO3-C-Mo composite alloy balls are added to the slag pool in batches, and the ratio of the density of the composite alloy balls to the density of the molten metal in the molten pool is 1.00-1.05.

[0025] It should be noted that the density of the NiMg-MoO3-C-Mo composite alloy ball added during the electroslag remelting process of the present invention is generally less than 3.0 g / cm 3, the density of slag is significantly lower than that of molten metal in the molten pool, so the density of the composite alloy ball is much higher than that of slag. When the composite alloy ball is added to the electroslag remelting system, the composite alloy ball quickly passes through the slag pool and reaches the surface of the molten metal pool. The ratio of its density to the density of the molten metal in the molten pool is 1.00-1.05. The difference between the density of the composite alloy ball used in the electroslag remelting process and the density of the molten metal in the molten pool is smaller than the difference between the density of the composite alloy ball used in vacuum induction melting and the density of the high-temperature molten metal. Therefore, its sedimentation speed in the molten metal pool is smaller than that in vacuum induction melting. Specifically, its density is slightly higher than the density of the high-temperature alloy liquid, and it slowly settles in the molten metal pool.

[0026] It should be noted that the control of sedimentation rate is of great significance for preventing alloy inclusions. During the electroslag remelting process, the bottom of the molten metal pool gradually solidifies under the strong cooling of the bottom water tank and the crystallizer. If the sedimentation rate of the composite alloy ball is too fast, it will quickly sink to the bottom of the molten metal pool, and may not have time to decompose and melt, and will be captured by the solidifying molten metal, thereby forming large particles of inclusions in the electroslag ingot, which seriously endangers the quality of the metal ingot. On the contrary, if the density of the composite alloy ball is less than the density of the molten metal in the molten pool, it will decompose on the surface of the molten metal pool, and the decomposition to form a large amount of Mg will react with the slag system, which will not only cause the loss of magnesium, but also change the composition of the slag system. Therefore, it is very important to control the density of the composite alloy ball so that it sinks slowly into the molten metal pool.

[0027] During the sedimentation process, under the high temperature of the molten pool and the crushing effect of CO gas, the NiMg alloy and the outer layer of metal Mo are crushed and dispersed, and quickly dissolved in the metal molten pool to prevent alloy inclusions. At the same time, due to the dispersion of NiMg, the magnesium vapor is evenly dispersed in the metal molten pool, which avoids the excessive concentration of magnesium on the surface of the molten pool, thereby avoiding the reaction of magnesium with the remelting slag system, and keeping the magnesium and slag system components in a balanced state, that is, the magnesium recovery rate can be improved, and the composition of the remelting slag system will not be changed, and the stability of the remelting process will not be affected. In addition, adding NiMg-MoO3-C-Mo composite alloy balls to the slag pool in batches is conducive to further preventing alloy inclusions and reducing the longitudinal deviation of the magnesium content in the electroslag ingot.

[0028] Furthermore, the diameter of the NiMg-MoO3-C-Mo composite alloy ball used in the electroslag remelting is 10 to 20 mm; and the diameter of the inner layer of the ball is 5 to 10 mm.

[0029] Furthermore, the particles of NiMg alloy in the inner layer of the NiMg-MoO3-C-Mo composite alloy ball used in electroslag remelting are 1 to 2 mm.

[0030] In the electroslag remelting process, the size of the composite alloy balls used is smaller than that of the inner and outer layers of the composite balls in the vacuum induction melting process. The smaller size of the composite alloy balls is conducive to their rapid melting and decomposition during the sedimentation of the molten metal pool. If the size is too large, it may settle to the bottom of the solidifying molten metal pool before it is melted and decomposed, causing heterogeneous inclusions in the electroslag ingot. By designing smaller-sized magnesium-enhanced composite alloy balls for the electroslag remelting process, the time for melting and decomposition is controlled, which further promotes the smooth decomposition of the composite alloy balls inside the molten metal pool and the completion of Mg alloying. For the vacuum induction melting process, since the crucible is full of liquid metal and there is no solidification process, the size of the composite gold balls melted by vacuum reaction can be slightly larger.

[0031] Furthermore, the NiMg alloy in the composite metal ball used for vacuum induction melting is 17% Mg-83% Ni.

[0032] Furthermore, the NiMg alloy in the composite metal ball used for electroslag remelting is 10% Mg-90% Ni.

[0033] During the vacuum induction melting process, the temperature of the molten metal is relatively low, generally around 1500°C. When the NiMg alloy is selected as 17% Mg-83% Ni, its alloy melting point is low, which is conducive to its decomposition and melting in the molten metal to complete the magnesium alloying. During the electroslag remelting process, the composite alloy ball needs to pass through the slag pool before entering the molten metal pool. Generally, the temperature of the slag pool exceeds 1700°C. If the NiMg alloy in the composite alloy ball still uses 17% Mg-83% Ni, it is possible that it will decompose during the process of passing through the slag pool, which will eventually reduce the magnesium recovery rate; therefore, 10% Mg-90% NiMg alloy particles with a higher alloy melting point should be used.

[0034] Furthermore, during the electroslag remelting process, NiMg-MoO3-C-Mo composite alloy balls are added every 5 to 10 minutes.

[0035] Furthermore, 1.0-1.5 kg of NiMg-MoO3-C-Mo composite alloy balls are added to each ton of consumable electrode remelted.

[0036] Furthermore, NiMg-MoO3-C-Mo composite alloy balls are added into the slag pool along the surface of the consumable electrode.

[0037] Further, the slag used for the electroslag remelting contains the following components in mass proportion: 42-50% CaF2, 20-25% MgF2, 2-6% Al2O3, 20-25% MgO, 1-2% TiO2, 2-4% NaF; and the weight ratio of CaF2 to MgF2 in the slag system is 2:1. It should be noted that the use of the CaF2-MgF2-MgO-Al2O3-TiO2-NaF multi-component composite slag system and the optimization design of the mass proportion of each component in the present invention are conducive to the chemical balance between aluminum and magnesium-containing compounds under high temperature conditions. Specifically, by adjusting the Al2O3, TiO2, and MgO components in the slag system, the burning and reduction of magnesium can be prevented, and the change of slag composition caused by the chemical reaction between aluminum and magnesium-containing compounds can be prevented, thereby affecting the stability of the remelting process and the quality of the product. Moreover, when the slag system contains reasonable CaF2, MgF2 and NaF, the slag system maintains reasonable melting point and viscosity, which can provide kinetic conditions for good chemical reactions between aluminum and magnesium-containing compounds.

[0038] Furthermore, the consumable electrode surface is polished, baked at 150-200° C. for 5-8 hours, and then electroslag remelted. The remelting process is performed using argon protection remelting, and the oxygen content in the atmosphere is ≤0.1%;

[0039] Furthermore, solid slag starting is adopted, and before arcing, rare earth silicon-magnesium alloy accounting for 0.03-0.06% of the slag mass is added; during the slag melting process, rare earth silicon-magnesium alloy accounting for 0.04-0.08% of the slag mass is added.

[0040] Furthermore, the high temperature alloy contains 0.003-0.01% Mg,

[0041] Furthermore, the high temperature alloy contains ≥1.0% Mo.

[0042] Furthermore, the density of the high temperature alloy is 7.5 to 8.5 g / cm 3 .

[0043] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0044] (1) The present invention adds NiMg-MoO3-C-Mo composite alloy balls with a density of 1.05 to 1.10 times that of the high-temperature molten metal into the vacuum induction melting process, so that the composite alloy balls quickly settle to the bottom of the high-temperature molten metal. At the same time, the temperature of the high-temperature molten metal is used to generate CO gas from the MoO3 and C inside the composite alloy balls. Under the crushing effect of the internal CO gas, the outer Mo coating layer is destroyed, and the NiMg alloy is dispersed in the molten metal. The Mg is absorbed by the high-temperature alloy during the gasification and floating process in the high-temperature molten metal, thereby improving the magnesium yield. Furthermore, the particles of the NiMg alloy in the inner layer of the spherical agglomerates are 2 to 5 mm, which is conducive to improving the dispersion degree of the NiMg alloy in the molten metal, thereby further improving the magnesium yield.

[0045] (2) The present invention further adds NiMg-MoO3-C-Mo composite alloy balls to the slag pool during the electroslag remelting process, and optimizes the density thereof, so that the ratio of its density to the density of the molten metal in the molten pool is 1.00-1.05, the difference between the density of the composite alloy balls and the density of the molten metal in the molten pool is reduced, and the slow sedimentation of the composite alloy balls in the molten metal pool and the dispersion effect of the internal CO gas on the NiMg alloy and Mo powder are controlled, thereby preventing alloy inclusions. At the same time, by settling the composite alloy balls into the interior of the molten metal pool, the excessive concentration of magnesium on the surface of the molten pool is avoided, thereby avoiding the reaction of magnesium with the remelting slag system, and maintaining a balanced state between magnesium and the slag system components. Furthermore, the particles of the NiMg alloy in the inner layer of the spherical pellets are 1-2 mm, which is conducive to improving the dispersion degree of the NiMg alloy in the molten metal, thereby further improving the magnesium recovery rate. The overall size of the composite alloy balls used in the electroslag remelting process is smaller. Through the above measures, the Mg recovery rate in the smelting process can be effectively improved, and the performance of the high-temperature alloy can be improved.

[0046] (3) The present invention further optimizes the design of the high-temperature alloy electroslag remelting process. According to the thermodynamic law of the reaction between aluminum and magnesium-containing compounds, a CaF2-MgF2-MgO-Al2O3-TiO2-NaF multi-component composite slag system is designed and the mass proportion of each component is optimized to maintain the chemical balance between aluminum and magnesium-containing compounds under high temperature conditions. This can not only inhibit the oxidation of magnesium, but also prevent the burning and reduction of magnesium. In addition, it can also prevent the chemical reaction between aluminum and magnesium-containing compounds from causing changes in the slag composition, thereby affecting the stability of the remelting process and product quality. DETAILED DESCRIPTION

[0047] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with embodiments.

[0048] The method for controlling the magnesium content in a high-temperature alloy provided by the present invention is suitable for controlling the magnesium content in the high-temperature alloy. The following embodiments and comparative examples are only used to explain the technical effects of the scheme of the present invention and should not be understood as limiting the composition of the high-temperature alloy to which the scheme is adapted.

[0049] Example 1

[0050] This embodiment provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy composition includes the following components in mass proportion: 2.6% Mo, 0.004-0.009% Mg, and its density is 7.9g / cm 3 .

[0051] The specific preparation of the high temperature alloy used in this embodiment includes the following:

[0052] (I) Preparation of NiMg-MoO3-C-Mo composite alloy balls

[0053] The preparation method of NiMg-MoO3-C-Mo composite alloy ball used for vacuum induction melting is as follows:

[0054] (1) Raw material composition: NiMg alloy composed of 17% Mg-83% Ni is crushed into 2-3 mm NiMg alloy particles; 80 mesh Mo powder, wherein the Mo content is ≥99.9%; 250 mesh MoO3 and C powder, wherein the mass ratio of C to MoO3 is 0.8:4.

[0055] (2) Preparation process: First, MoO3 and C are fully mixed, and then the mixture of MoO3 and C and 2-3 mm NiMg alloy particles are mixed and pressed into 22 mm inner layer pellets, and finally the inner layer pellets are coated with Mo powder and pressed into NiMg-MoO3-C-Mo composite alloy balls with a diameter of 36 mm.

[0056] The density of the composite alloy ball prepared for vacuum induction melting is 8.7 g / cm 3 The mass ratio of NiMg-MoO3-C-Mo in the composite alloy ball is 9.00%:5.00%:1%:85.00%, which is equivalent to the mass proportion of magnesium element in the composite alloy ball being 1.53%.

[0057] The preparation method of NiMg-MoO3-C-Mo composite alloy ball in electroslag remelting is as follows:

[0058] (1) Raw material composition: NiMg alloy composed of 10% Mg-90% Ni is crushed into 1-2 mm NiMg alloy particles; 80 mesh Mo powder, wherein the Mo content is ≥99.9%; 250 mesh MoO3 and C powder, wherein the mass ratio of C to MoO3 is 0.8:4.

[0059] (2) Preparation process: First, MoO3 and C are fully mixed, and then the mixture of MoO3 and C and 1-2 mm NiMg alloy particles are mixed and pressed into 8 mm inner layer pellets, and finally the inner layer pellets are coated with Mo powder and pressed into NiMg-MoO3-C-Mo composite alloy balls with a diameter of 16 mm.

[0060] The density of the prepared composite alloy ball for electroslag remelting is 8.2g / cm 3 The mass ratio of NiMg-MoO3-C-Mo in the composite metal ball is 7.00%:2.50%:0.5%:90%, which is equivalent to the mass proportion of magnesium element in the composite alloy ball being 0.7%.

[0061] (ii) Vacuum induction melting and electroslag remelting

[0062] The Mo content in the smelted high-temperature alloy is added from two parts. The first part is added to the vacuum induction furnace in the form of pure metal in S1, and the second part is added in the form of composite alloy balls.

[0063] S1: According to the composition requirements of the high-temperature alloy to be smelted, the amount of various raw materials is calculated according to the mass ratio, and all other alloys except Al, Mg and Ti are added to the vacuum induction furnace for melting and refining; the added alloy materials are all pure metal materials;

[0064] S2: vacuum induction refining temperature is 1450-1500℃, refining time is 8 hours, vacuum degree is ≤2Pa; 10 minutes before the end of refining, 2% Al and 1% Ti are added to the high-temperature alloy liquid by mass; then electromagnetic stirring is used for 2 minutes, and then induction heating is started to keep the temperature between 1450 and 1460℃;

[0065] S3: high-purity argon gas is introduced into the vacuum chamber. When the pressure of the vacuum chamber reaches 25000Pa, 0.4% of the mass ratio of NiMg-MoO3-C-Mo composite alloy balls are added to the metal liquid, and then the alloy liquid is allowed to stand for 4 minutes, induction heating is started, and heating is stopped after the temperature rises to 1480°C, electromagnetic stirring is started for 1 minute, and finally a metal consumable electrode is cast;

[0066] S4: After the surface of the consumable electrode is polished and baked at 200°C for 5 hours, the electroslag remelting is carried out. The electroslag remelting is started by solid slag, and the remelting process is protected by argon gas. The oxygen content in the atmosphere is ≤0.1%; the slag material used is composed of 46% CaF2, 23% MgF2, 6% Al2O3, 20% MgO, 2% TiO2, and 4% NaF; the weight ratio of CaF2 to MgF2 in the slag system is 2:1. Based on the mass of the above slag material as a whole, before arcing, add 0.04% of the slag material mass to the above slag material and mix it evenly. During the slag melting process, add 0.06% of the slag material mass to the rare earth silicon magnesium alloy. During the electroslag remelting process, add NiMg-MoO3-C-Mo composite alloy balls to the slag pool along the surface of the consumable electrode once every 8 minutes, and add 1.2kg of NiMg-MoO3-C-Mo composite alloy balls for every ton of consumable electrode remelted.

[0067] S5: demoulding the electroslag ingot after remelting, and the smelting process is completed.

[0068] A high-temperature alloy metal ingot was prepared, and the measured Mg content in the metal ingot was 0.0062%. The composite alloy balls used in the preparation process of the high-temperature alloy metal ingot contained 0.0714 kg of magnesium per ton of steel. By adding the composite alloy balls, the metal ingot obtained had a total magnesium increase of 0.062 kg per ton of steel, and the magnesium recovery rate was 86.83%.

[0069] Comparative Example 1

[0070] This comparison provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy is the same as that in Example 1. The difference from Example 1 is that the alloy balls used for increasing magnesium and molybdenum alloying are different and the amounts used are different. The rest of the operations are basically the same.

[0071] Specifically, the preparation method of the alloy balls used in vacuum induction melting is: 12.45% Ni-2.55% Mg-85% Mo alloy is directly crushed into NiMgMo alloy particles with a particle size less than 2-3 mm, and the NiMgMo alloy particles are used to press into 30 mm NiMgMo composite alloy balls, whose density is the same as the density of the composite alloy balls used for vacuum induction melting in Example 1.

[0072] The preparation method of the alloy balls used in electroslag remelting is as follows: 22.5% Ni-2.5% Mg-75% Mo alloy is crushed into NiMgMo alloy particles with a particle size of less than 1-2 mm, and the NiMgMo alloy particles are used to press into 18 mm NiMgMo composite alloy balls, whose density is the same as the density of the composite alloy balls used for electroslag remelting in Example 1.

[0073] And the amounts of the above alloy pellets used in vacuum induction melting and electroslag remelting are different.

[0074] Specifically, in vacuum induction melting, 0.50% of NiMgMo composite alloy balls are added to the vacuum induction molten metal liquid. In electroslag remelting, 1.3 kg of NiMgMo composite alloy balls are added to each ton of consumable electrode remelted.

[0075] The obtained high temperature alloy metal ingot has a measured Mg content of 0.0049%. The composite metal alloy ball used in the preparation of the high temperature alloy metal ingot contains 0.16 kg of magnesium per ton of steel, and the obtained metal ingot has a total magnesium content of 0.049 kg per ton of steel, with a magnesium yield of 30.62%.

[0076] Comparative Example 2

[0077] This comparative example provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy is the same as that in Example 1. The difference from Example 1 is that the composite alloy balls used for increasing magnesium and molybdenum alloying are different and the amounts used are different. The rest of the operations are basically the same.

[0078] Specifically: The preparation method of NiMg-Mo composite alloy balls used in vacuum induction melting is as follows: A NiMg alloy composed of 17% Mg-83% Ni is crushed into NiMg alloy particles with a particle size of 2 to 3 mm, and the NiMg alloy particles are pressed into 22 mm inner layer pellets, which are coated with 80-mesh Mo powder on the outside to obtain composite alloy balls with a particle size of 36 mm, wherein the mass ratio of NiMg-Mo is 15%:85%, and the mass proportion of magnesium element in the composite alloy ball is 2.55%, and its density is the same as the density of the composite alloy ball used for vacuum induction melting in Example 1.

[0079] The preparation process of the NiMg-Mo composite alloy pellets used in electroslag remelting is as follows: a NiMg alloy composed of 10% Mg-90% Ni is crushed into NiMg alloy particles with a particle size of 1 to 2 mm, and the NiMg alloy particles are pressed into 8 mm inner layer pellets, which are coated with 80-mesh Mo powder on the outside to obtain composite alloy pellets with a particle size of 16 mm, wherein the mass ratio of NiMg-Mo is 15%:85%, and the mass proportion of magnesium element in the composite alloy ball is 1.5%, and its density is the same as the density of the composite alloy ball used for electroslag remelting in Example 1.

[0080] Specifically, in vacuum induction melting, 0.5% of NiMg-Mo alloy balls are added to the high-temperature alloy liquid by mass; in electroslag remelting, 0.1.3 kg of NiMg-Mo composite alloy balls are added to each ton of consumable electrode remelted, and the rest of the operations are basically the same.

[0081] The obtained high temperature alloy metal ingot has a measured Mg content of 0.0036%. The composite metal alloy ball used in the preparation of the high temperature alloy metal ingot contains 0.148 kg of magnesium per ton of steel, and the obtained metal ingot has a total magnesium content of 0.036 kg per ton of steel, with a magnesium yield of 24.32%.

[0082] Comparative Example 3

[0083] This comparative example provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy is the same as that in Example 1. The difference from Example 1 is that the composite alloy balls used for increasing magnesium and molybdenum alloying are different and the amounts used are different. The rest of the operations are basically the same.

[0084] Specifically: The preparation method of NiMg-Mo composite alloy balls used in vacuum induction melting is as follows: A NiMg alloy composed of 17% Mg-83% Ni is crushed into NiMg alloy particles with a particle size of 2 to 3 mm, and the NiMg alloy particles are pressed into 22 mm inner layer pellets, which are coated with 80-mesh Mo powder on the outside to obtain composite alloy balls with a particle size of 36 mm, wherein the mass ratio of NiMg-Mo is 15%:85%, and the mass proportion of magnesium element in the composite alloy ball is 2.55%, and its density is the same as the density of the composite alloy ball used for vacuum induction melting in Example 1.

[0085] The preparation process of NiMg-Mo composite alloy pellets used in electroslag remelting is as follows: a NiMg alloy composed of 10% Mg-90% Ni is crushed into NiMg alloy particles with a particle size of 1 to 2 mm, and the NiMg alloy particles are pressed into 8 mm inner layer pellets, and 80 mesh Mo powder is wrapped on the outside to obtain a composite alloy pellet with a particle size of 16 mm, wherein the mass ratio of NiMg-Mo is 40%:60%; the mass proportion of magnesium in the composite alloy ball is 4%, and its density is 7.6 g / cm 3 , slightly smaller than the molten metal in the molten pool.

[0086] The above-mentioned composite alloy balls are used in different amounts in vacuum induction melting and electroslag remelting. Specifically, in vacuum induction melting, 0.6% of NiMg-Mo alloy balls are added to the high-temperature alloy liquid by mass; in electroslag remelting, 1.4 kg of NiMg-Mo composite alloy balls are added for every ton of consumable electrodes remelted.

[0087] The obtained high temperature alloy metal ingot has a measured Mg content of 0.0045%. The composite metal alloy ball used in the preparation of the high temperature alloy metal ingot contains 0.209 kg / ton of steel of magnesium, and the obtained metal ingot has a total magnesium content of 0.045 kg / ton of steel, with a magnesium recovery rate of 21.53%.

[0088] Comparative Example 4

[0089] This comparative example provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy is the same as that in Example 1. The difference from Example 1 is that the composite alloy balls used for increasing magnesium and molybdenum alloying in vacuum induction melting are different and the amounts used are different, and the rest of the operations are basically the same.

[0090] Specifically: The preparation method of NiMg-MoO3-C-Mo composite alloy balls used in vacuum induction melting is as follows: a NiMg alloy composed of 17% Mg-83% Ni is crushed into NiMg alloy particles with a particle size of 2 to 3 mm, and the NiMg alloy particles are pressed into 22 mm inner layer pellets, which are coated with 80 mesh Mo powder on the outside to obtain composite alloy balls with a particle size of 36 mm, and the mass ratio of NiMg-MoO3-C-Mo is 22%:15%:3%:60%, which is equivalent to 3.74% of the mass of the magnesium element in the composite alloy ball, and its density is less than the density of the vacuum induction molten metal liquid.

[0091] The amounts of the composite alloy balls used in vacuum induction melting are different. Specifically, in vacuum induction melting, NiMg-Mo alloy balls are added in an amount of 0.7% by mass of the high-temperature alloy liquid.

[0092] A high-temperature alloy metal ingot is prepared, and the measured Mg content in the metal ingot is 0.0048%. The composite metal alloy ball used in the preparation process of the high-temperature alloy metal ingot contains 0.272 kg of magnesium per ton of steel, and the obtained metal ingot has a total magnesium content of 0.048 kg per ton of steel, and the magnesium recovery rate is 17.65%.

[0093] Comparative Example 5

[0094] This comparative example provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy is the same as that in Example 1. The difference from Example 1 is that the composite alloy balls used for increasing magnesium and molybdenum alloying in electroslag remelting are different and the amounts used are different, and the rest of the operations are basically the same.

[0095] Specifically: The preparation method of NiMg-MoO3-C-Mo composite alloy balls used in electroslag remelting is as follows: a NiMg alloy composed of 10% Mg-90% Ni is crushed into NiMg alloy particles with a particle size of 1 to 2 mm, and the NiMg alloy particles are pressed into 8 mm inner layer balls, which are coated with 80-mesh Mo powder on the outside to obtain composite alloy balls with a particle size of 16 mm, wherein the mass ratio of NiMg-MoO3-C-Mo is 23%:10%:2%:65%, which is equivalent to a magnesium element mass proportion of 2.3% in the composite alloy ball, and its density is less than the density of the molten metal in the molten pool.

[0096] The amount of the above-mentioned composite alloy balls used in electroslag remelting is different. Specifically, in electroslag remelting, 1.5 kg of NiMg-Mo composite alloy balls are added for every ton of consumable electrode remelted.

[0097] The obtained high temperature alloy metal ingot has a measured Mg content of 0.0034%. The composite metal alloy ball used in the preparation of the high temperature alloy metal ingot contains 0.099 kg of magnesium per ton of steel, and the obtained metal ingot has a total magnesium content of 0.034 kg per ton of steel, with a magnesium yield of 34.34%.

[0098] Comparative Example 6

[0099] This comparative example provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy is the same as that in Example 1. The difference from Example 1 is that the slag system used in the electroslag remelting is different. The slag material used is composed of 48% CaF2, 22% Al2O3, 3% TiO2, 22% CaO, 5% Mg, and no rare earth silicon-magnesium alloy is added. The rest of the operations are basically the same.

[0100] A high-temperature alloy metal ingot was prepared, and the measured Mg content in the metal ingot was 0.0026%. The composite metal alloy ball used in the preparation process of the high-temperature alloy metal ingot contained 0.0714 kg / ton of steel of magnesium, and the actual increase in magnesium was 0.026 kg / ton of steel, and the magnesium recovery rate was 36.41%.

[0101] Example 2

[0102] This embodiment provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy contains the following components in mass proportion: 1.6% Mo, 0.006-0.01% Mg, and a density of 8.2 g / cm 3 .

[0103] The specific preparation of the high temperature alloy used in this embodiment includes the following:

[0104] (I) Preparation of NiMg-MoO3-C-Mo composite alloy balls

[0105] The preparation method of NiMg-MoO3-C-Mo composite alloy ball used for vacuum induction melting is as follows:

[0106] (1) Raw material composition: NiMg alloy composed of 17% Mg-83% Ni is crushed into 4-5 mm NiMg alloy particles; 50 mesh Mo powder, wherein the Mo content is ≥ 99.9%; 200 mesh MoO3 and C powder, wherein the mass ratio of C to MoO3 is 0.9:4;

[0107] (2) Preparation process: First, MoO3 and C are fully mixed, and then the mixture of MoO3 and C and 4-5 mm NiMg alloy particles are mixed and pressed into 25 mm inner layer pellets, and finally the inner layer pellets are coated with Mo powder and pressed into NiMg-MoO3-C-Mo composite alloy balls with a diameter of 40 mm.

[0108] The density of the composite alloy ball prepared for vacuum induction melting is 8.8 g / cm 3 The mass ratio of NiMg-MoO3-C-Mo in the composite alloy ball is 7.00%:2.45%:0.55%:90%, which is equivalent to the mass proportion of magnesium element in the composite alloy ball being 1.19%.

[0109] The preparation method of NiMg-MoO3-C-Mo composite alloy ball in electroslag remelting is as follows:

[0110] (1) Raw material composition: NiMg alloy composed of 10% Mg-90% Ni is crushed into 1-2 mm NiMg alloy particles; 50 mesh Mo powder, wherein the Mo content is ≥ 99.9%; 200 mesh MoO3 and C powder, wherein the mass ratio of C to MoO3 is 0.9:4;

[0111] (2) Preparation process: First, MoO3 and C are fully mixed, and then the mixture of MoO3 and C and 1-2 mm NiMg alloy particles are mixed and pressed into 10 mm inner layer pellets, and finally the inner layer pellets are coated with Mo powder and pressed into NiMg-MoO3-C-Mo composite alloy balls with a diameter of 20 mm;

[0112] The density of the prepared composite alloy ball for electroslag remelting is 8.4 g / cm 3 The mass ratio of NiMg-MoO3-C-Mo in the composite alloy ball is 7.60%:1.96%:0.44%:90%, of which the mass ratio of magnesium element in the composite alloy ball is 0.76%.

[0113] (ii) Vacuum induction melting and electroslag remelting

[0114] S1: According to the composition requirements of the high-temperature alloy to be smelted, the amount of various raw materials is calculated according to the mass ratio, and all other alloys except Al, Mg and Ti are added to the vacuum induction furnace for melting and refining; the added alloy materials are all pure metal materials;

[0115] S2: vacuum induction refining temperature 1450 ~ 1500 ℃, refining time 10 hours, vacuum degree ≤ 2Pa; 15 minutes before the end of refining, add 0.4% Al and 3% Ti to the high-temperature alloy liquid by mass; then use electromagnetic stirring for 3 minutes, and then start induction heating to keep the temperature between 1450 ~ 1460 ℃;

[0116] S3: high-purity argon gas is introduced into the vacuum chamber. When the pressure of the vacuum chamber reaches 20000Pa, NiMg-MoO3-C-Mo composite alloy balls accounting for 0.6% of the mass ratio of the metal liquid are added, and then the alloy liquid is allowed to stand for 5 minutes, induction heating is started, and heating is stopped after the temperature rises to 1450°C, electromagnetic stirring is started for 1 minute, and finally a metal consumable electrode is cast;

[0117] S4: After the surface of the consumable electrode is polished and baked at 150°C for 8 hours, the electroslag remelting is performed. The electroslag remelting is started by solid slag, and the remelting process is protected by argon gas, and the oxygen content in the atmosphere is ≤0.1%; the slag material used is composed of 50% CaF2, 25% MgF2, 2% Al2O3, 20% MgO, 1% TiO2, and 2% NaF; the weight ratio of CaF2 to MgF2 in the slag system is 2:1. Based on the mass of the above slag material as a whole, before arcing, add 0.06% of the slag material mass of rare earth silicon-magnesium alloy to the above slag material and mix it evenly. During the slag melting process, add 0.08% of the slag material mass of rare earth silicon-magnesium alloy evenly; during the electroslag remelting process, add NiMg-MoO3-C-Mo composite alloy balls to the slag pool along the surface of the consumable electrode once every 5 minutes, and add 1.5kg of NiMg-MoO3-C-Mo composite alloy balls for every ton of consumable electrode remelted.

[0118] S5: demoulding the electroslag ingot after remelting, and the smelting process is completed.

[0119] The obtained high temperature alloy metal ingot has a measured Mg content of 0.0069%. The composite metal alloy ball used in the preparation of the high temperature alloy metal ingot contains 0.0856 kg of magnesium per ton of steel, and the obtained metal ingot has a total magnesium content of 0.069 kg per ton of steel, with a magnesium recovery rate of 80.61%.

[0120] Example 3

[0121] This embodiment provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy contains the following components by mass: 3.3% Mo, 0.003-0.007% Mg, and a density of 7.8 g / cm 3 The specific preparation of the high temperature alloy used in this embodiment includes the following:

[0122] (I) Preparation of NiMg-MoO3-C-Mo composite alloy balls

[0123] The preparation method of NiMg-MoO3-C-Mo composite alloy ball used for vacuum induction melting is as follows:

[0124] (1) Raw material composition: NiMg alloy composed of 17% Mg-83% Ni is crushed into 2-3 mm NiMg alloy particles; 100 mesh Mo powder, wherein the Mo content is ≥ 99.9%; 250 mesh MoO3 and C powder, wherein the mass ratio of C to MoO3 is 0.85:4;

[0125] (2) Preparation process: First, MoO3 and C are fully mixed, and then the mixture of MoO3 and C and 2-3 mm NiMg alloy particles are mixed and pressed into a 20 mm inner layer pellet, and finally the inner layer pellet is coated with Mo powder and pressed into a NiMg-MoO3-C-Mo composite alloy ball with a diameter of 30 mm.

[0126] The density of the composite alloy ball prepared for vacuum induction melting is 8.4 g / cm 3 The mass ratio of NiMg-MoO3-C-Mo in the composite alloy ball is 11.40%:2.97%:0.63%:85%, of which the mass ratio of magnesium element in the composite alloy ball is 0.76%.

[0127] The preparation method of NiMg-MoO3-C-Mo composite alloy ball in electroslag remelting is as follows:

[0128] (1) Raw material composition: NiMg alloy composed of 10% Mg-90% Ni is crushed into 1-2 mm NiMg alloy particles; 100 mesh Mo powder, wherein the Mo content is ≥ 99.9%; 250 mesh MoO3 and C powder, wherein the mass ratio of C to MoO3 is 0.85:4;

[0129] (2) Preparation process: First, MoO3 and C are fully mixed, and then the mixture of MoO3 and C and 1-2 mm NiMg alloy particles are mixed and pressed into 5 mm inner layer pellets, and finally the inner layer pellets are coated with Mo powder and pressed into NiMg-MoO3-C-Mo composite alloy balls with a diameter of 10 mm.

[0130] The density of the prepared composite alloy ball for electroslag remelting is 8.0 g / cm 3 The mass ratio of NiMg-MoO3-C-Mo in the composite alloy ball is 14.00%:4.95%:1.05%:80%, of which the mass ratio of magnesium element in the composite alloy ball is 1.4%.

[0131] (ii) Vacuum induction melting and electroslag remelting

[0132] S1: According to the composition requirements of the high-temperature alloy to be smelted, the amount of various raw materials is calculated according to the mass ratio, and all other alloys except Al, Mg and Ti are added to the vacuum induction furnace for melting and refining; the added alloy materials are all pure metal materials;

[0133] S2: vacuum induction refining temperature 1450 ~ 1500 ℃, refining time 2 hours, vacuum degree ≤ 2Pa; 12 minutes before the end of refining, add 4% Al and 1% Ti to the high-temperature alloy liquid by mass; then use electromagnetic stirring for 1 minute, and then start induction heating to keep the temperature between 1450 ~ 1460 ℃;

[0134] S3: high-purity argon gas is introduced into the vacuum chamber. When the pressure of the vacuum chamber reaches 30000Pa, NiMg-MoO3-C-Mo composite alloy balls accounting for 0.2% of the mass ratio of the high-temperature alloy liquid are added, and then the alloy liquid is allowed to stand for 3 minutes, induction heating is started, and heating is stopped after the temperature rises to 1500°C, electromagnetic stirring is started for 1 minute, and finally a metal consumable electrode is cast;

[0135] S4: After the surface of the consumable electrode is polished and baked at 180°C for 6 hours, the electroslag remelting is performed. The electroslag remelting is started by solid slag, and the remelting process is protected by argon gas, and the oxygen content in the atmosphere is ≤0.1%; the slag material used is composed of 42% CaF2, 21% MgF2, 6% Al2O3, 25% MgO, 2% TiO2, and 4% NaF; the weight ratio of CaF2 to MgF2 in the slag system is 2:1. Based on the mass of the above slag material as a whole, before arcing, add 0.03% of the slag material mass to the above slag material and mix it evenly. During the slag melting process, add 0.04% of the slag material mass to the rare earth silicon magnesium alloy; during the electroslag remelting process, add NiMg-MoO3-C-Mo composite alloy balls to the slag pool along the surface of the consumable electrode once every 10 minutes, and add 1.0 kg of NiMg-MoO3-C-Mo composite alloy balls for every ton of consumable electrode remelted.

[0136] S5: demoulding the electroslag ingot after remelting, and the smelting process is completed.

[0137] The obtained high temperature alloy metal ingot has a measured Mg content of 0.0047%. The composite metal alloy ball used in the preparation of the high temperature alloy metal ingot contains 0.0542 kg of magnesium per ton of steel, and the obtained metal ingot has a total magnesium content of 0.047 kg per ton of steel, with a magnesium recovery rate of 86.72%.

[0138] Example 4

[0139] This embodiment provides a method for controlling the magnesium content in a high-temperature alloy. The smelted high-temperature alloy contains the following components by mass: 2.0% Mo, 0.005-0.01% Mg, and a density of 8.0 g / cm 3 .

[0140] The specific preparation of the high temperature alloy of this embodiment includes the following steps:

[0141] (I) Preparation of NiMg-MoO3-C-Mo composite alloy balls

[0142] The preparation method of NiMg-MoO3-C-Mo composite alloy ball used for vacuum induction melting is as follows:

[0143] (1) Raw material composition: NiMg alloy composed of 17% Mg-83% Ni is crushed into 2-3 mm NiMg alloy particles; 100 mesh Mo powder, wherein the Mo content is ≥ 99.9%; 250 mesh MoO3 and C powder, wherein the mass ratio of C to MoO3 is 0.9:4;

[0144] (2) Preparation process: First, MoO3 and C are fully mixed, and then the mixture of MoO3 and C and 2-3 mm NiMg alloy particles are mixed and pressed into a 20 mm inner layer pellet, and finally the inner layer pellet is coated with Mo powder and pressed into a NiMg-MoO3-C-Mo composite alloy ball with a diameter of 30 mm.

[0145] The density of the composite alloy ball prepared for vacuum induction melting is 8.5 g / cm 3 The mass ratio of NiMg-MoO3-C-Mo in the composite alloy ball is 10.55:2.00:0.45%:87.00%, which is equivalent to the mass proportion of magnesium element in the composite alloy ball being 1.79%.

[0146] The preparation method of NiMg-MoO3-C-Mo composite alloy ball in electroslag remelting is as follows:

[0147] (1) Raw material composition: NiMg alloy composed of 10% Mg-90% Ni is crushed into 1-2 mm NiMg alloy particles; 100 mesh Mo powder, wherein the Mo content is ≥ 99.9%; 250 mesh MoO3 and C powder, wherein the mass ratio of C to MoO3 is 0.9:4;

[0148] (2) Preparation process: First, MoO3 and C are fully mixed, and then the mixture of MoO3 and C and 1-2 mm NiMg are mixed and pressed into a 5 mm inner layer pellet, and finally the inner layer pellet is coated with Mo powder and pressed into a NiMg-MoO3-C-Mo composite alloy ball with a diameter of 10 mm.

[0149] The density of the prepared composite alloy ball for electroslag remelting is 8.2g / cm 3 The mass proportions of NiMg-MoO3-C-Mo in the composite alloy ball are 11.10%, 4.00%, 0.9% and 84.00%, which is equivalent to the mass proportion of magnesium element in the composite alloy ball being 1.11%.

[0150] (ii) Vacuum induction melting and electroslag remelting

[0151] S1: According to the composition requirements of the high-temperature alloy to be smelted, the amount of various raw materials is calculated according to the mass ratio, and all other alloys except Al, Mg and Ti are added to the vacuum induction furnace for melting and refining; the added alloy materials are all pure metal materials;

[0152] S2: vacuum induction refining temperature 1450 ~ 1500 ℃, refining time 8 hours, vacuum degree ≤ 2Pa; 12 minutes before the end of refining, add 2% Al and 2% Ti to the high-temperature alloy liquid by mass; then use electromagnetic stirring for 1 minute, and then start induction heating to keep the temperature between 1450 ~ 1460 ℃;

[0153] S3: high-purity argon gas is introduced into the vacuum chamber. When the pressure of the vacuum chamber reaches 30000Pa, NiMg-MoO3-C-Mo composite alloy balls accounting for 0.4% of the mass ratio of the high-temperature alloy liquid are added, and then the alloy liquid is allowed to stand for 5 minutes, induction heating is started, and heating is stopped after the temperature rises to 1500°C, electromagnetic stirring is started for 1 minute, and finally a metal consumable electrode is cast;

[0154] S4: After the surface of the consumable electrode is polished and baked at 200°C for 5 hours, the electroslag remelting is carried out. The electroslag remelting is started by solid slag, and the remelting process is protected by argon gas, and the oxygen content in the atmosphere is ≤0.1%; the slag material used is composed of 48% CaF2, 24% MgF2, 4% Al2O3, 23% MgO, 1% TiO2, and 3% NaF; the weight ratio of CaF2 to MgF2 in the slag system is 2:1. Based on the mass of the above slag material as a whole, before arcing, add 0.06% of the slag material mass to the above slag material and mix it evenly. During the slag melting process, add 0.08% of the slag material mass to the rare earth silicon magnesium alloy; during the electroslag remelting process, add NiMg-MoO3-C-Mo composite alloy balls to the slag pool along the surface of the consumable electrode once every 5 minutes, and add 1.2kg of NiMg-MoO3-C-Mo composite alloy balls for every ton of consumable electrode remelted.

[0155] S5: demoulding the electroslag ingot after remelting, and the smelting process is completed.

[0156] A high-temperature alloy metal ingot was prepared, and the measured Mg content in the metal ingot was 0.0072%. The composite metal alloy ball and rare earth silicon-magnesium alloy used in the preparation process of the high-temperature alloy metal ingot contained 0.0879 kg of magnesium per ton of steel, and the obtained metal ingot had a total magnesium content of 0.072 kg per ton of steel, and the magnesium recovery rate was 81.91%.

Claims

1. A method for controlling the magnesium content in a high temperature alloy, characterized in that: include: According to the composition requirements of the high-temperature alloy to be smelted, the raw materials are subjected to vacuum induction melting; Adding NiMg-MoO3-C-Mo composite alloy balls into the vacuum induction molten metal liquid to continue smelting to perform Mg alloying treatment; the density ratio of the NiMg-MoO3-C-Mo composite alloy balls to the density of the metal liquid is 1.05-1.10, and the NiMg-MoO3-C-Mo composite alloy balls include inner layer pellets and Mo powder wrapped outside the inner layer pellets, and the raw materials of the inner layer pellets include MoO3, C and NiMg alloy; Casting the molten metal after Mg alloying treatment into a consumable electrode; and The consumable electrode is electroslag remelted to obtain an electroslag ingot.

2. The method for controlling the magnesium content in a high temperature alloy according to claim 1, characterized in that: The addition amount of the NiMg-MoO3-C-Mo composite alloy ball accounts for 0.2-0.6% of the mass of the molten metal; And / or the mass ratio of C to MoO3 in the NiMg-MoO3-C-Mo composite alloy ball is 0.8-0.9:

4.

3. The method for controlling the magnesium content in a high temperature alloy according to claim 1, characterized in that: The particle size of the NiMg alloy in the NiMg-MoO3-C-Mo composite alloy ball is 2 to 5 mm; and / or the particle size of MoO3 and C in the NiMg-MoO3-C-Mo composite alloy ball is 200-250 mesh; And / or the particle size of Mo powder is 50-100 mesh.

4. The method for controlling the magnesium content in a high temperature alloy according to claim 1, characterized in that: The diameter of the NiMg-MoO3-C-Mo composite alloy ball is 30-40 mm, and the diameter of the inner layer ball is 20-25 mm; And / or when preparing the composite alloy ball, MoO3 and C are first mixed, and then the mixture of MoO3 and C and NiMg particles are mixed to form an inner layer pellet, and finally Mo powder is coated on the outside of the inner layer pellet.

5. The method for controlling the magnesium content in a high temperature alloy according to claim 1, characterized in that: Argon gas is introduced into the vacuum chamber, and when the pressure of the vacuum chamber reaches 20000-30000 Pa, NiMg-MoO3-C-Mo composite alloy balls are added into the vacuum induction molten metal liquid; And / or after adding NiMg-MoO3-C-Mo composite alloy balls into the vacuum induction molten metal liquid, the alloy liquid is first allowed to stand for 3 to 5 minutes, and then induction heating is started, and heating is stopped after the temperature rises to 1450 to 1500°C, electromagnetic stirring is started for 1 minute, and finally the metal consumable electrode is cast; and / or 10 to 15 minutes before the end of refining, add 0.4 to 4.0% Al and 1.0 to 3.0% Ti by mass ratio to the vacuum induction molten metal; electromagnetic stirring for 1 to 3 minutes, then start induction heating to keep the temperature between 1450 and 1460° C.; then add NiMg-MoO3-C-Mo composite alloy balls to the vacuum induction molten metal; And / or the temperature of the vacuum induction refining is 1450-1500° C., the refining time is 2-10 hours, and the vacuum degree is ≤2Pa.

6. The method for controlling the magnesium content in a high temperature alloy according to any one of claims 1 to 5, characterized in that: During the electroslag remelting of the consumable electrode, NiMg-MoO3-C-Mo composite alloy balls are added to the slag pool in batches, and the density ratio of the composite alloy balls to the density of the molten metal in the molten pool is 1.00-1.

05.

7. The method for controlling the magnesium content in a high temperature alloy according to claim 6, characterized in that: The diameter of the NiMg-MoO3-C-Mo composite alloy ball used in the electroslag remelting is 10-20 mm; and the diameter of the inner layer of the ball is 5-10 mm; And / or the particle size of the NiMg alloy in the inner layer of the NiMg-MoO3-C-Mo composite alloy ball used in electroslag remelting is 1 to 2 mm; And / or the NiMg alloy in the composite metal ball used for vacuum induction melting is 17% Mg-83% Ni; And / or the NiMg alloy in the composite metal ball used for electroslag remelting is 10% Mg-90% Ni.

8. The method for controlling the magnesium content in a high temperature alloy according to claim 6, characterized in that: During the electroslag remelting process, NiMg-MoO3-C-Mo composite alloy balls are added every 5 to 10 minutes; And / or add 1.0-1.5kg of NiMg-MoO3-C-Mo composite alloy balls for every ton of consumable electrode remelted; and / or NiMg-MoO3-C-Mo composite alloy balls are added into the slag pool along the surface of the consumable electrode.

9. The method for controlling the magnesium content in a high temperature alloy according to claim 6, characterized in that: The slag used in the electroslag remelting comprises the following components in percentage by weight: 42-50% CaF2, 20-25% MgF2, 2-6% Al2O3, 20-25% MgO, 1-2% TiO2, 2-4% NaF; and the weight ratio of CaF2 to MgF2 in the slag system is 2:1; And / or the surface of the consumable electrode is polished and baked at 150-200°C for 5-8 hours before electroslag remelting, the remelting process adopts argon protection remelting, and the oxygen content in the atmosphere is ≤0.1%; and / or solid slag is used for starting, and before arcing, rare earth silicon-magnesium alloy accounting for 0.03-0.06% of the slag mass is added; during the slag melting process, rare earth silicon-magnesium alloy accounting for 0.04-0.08% of the slag mass is added.

10. The method for controlling the magnesium content in a high temperature alloy according to claim 6, characterized in that: The high temperature alloy contains 0.003-0.01% Mg; and / or ≥1.0%Mo; And / or the density of the high temperature alloy is 7.5-8.5 g / cm 3 .