Nickel-chromium-rare earth intermediate alloy and preparation method and additive thereof

Abstract

The invention discloses a nickel-chromium-rare earth intermediate alloy as well as a preparation method and an additive thereof. The intermediate alloy comprises nickel, chromium and rare earth metal, the content of nickel in the intermediate alloy is 5wt%-90wt%, the content of chromium is 5wt%-50wt%, and the content of rare earth metal is 5wt%-90wt%; the density of the intermediate alloy ranges from 7.7 g / cm < 3 > to 8.76 g / cm < 3 >, the melting point ranges from 1354 DEG C to 1490 DEG C, the particle size of inclusions is smaller than 30 microns, and the oxygen content is smaller than 150 ppm. The density and melting point close to those of nickel-based alloy or molten steel are obtained through reasonable adjustment of the component proportion, uniform diffusion and dissolution can be achieved after adding, and the problems of oxidation burning loss, unstable component control, component segregation and smelting load increase caused by melting point difference and density difference in the nickel-based alloy and steel metallurgy adding process of nickel, chromium and rare earth are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a nickel-chromium-rare earth master alloy and a preparation method and additives thereof. Background Art

[0002] Nickel, chromium and rare earth are important alloying elements for nickel-based high-temperature alloys and various special steels such as stainless steel, pipeline steel and heat-resistant steel. After addition, they can effectively improve the corrosion resistance, fatigue resistance and oxidation resistance of materials through melt purification, inclusion modification, micro-alloying and other effects. At present, the following problems exist in the process of adding nickel, chromium and rare earth to nickel-based alloys and molten steel alloying: (1) Chromium and rare earth are mostly added as single raw materials in the process of preparing nickel-based alloys. Therefore, there are usually problems such as severe oxidation and burning, component segregation and increased smelting load due to density differences and melting point differences. (2) In the process of adding molten steel alloying, low-density, low-melting-point and highly active rare earth metals have problems such as unstable component control, poor uniformity and oxidation and burning when used as molten steel alloying additives. Although a large number of process experiments and studies have been carried out at home and abroad on the composition, form, and addition method of rare earth additives for molten steel alloying, including: ladle argon blowing and pressure injection method, ladle rare earth powder injection method, tundish / crystallizer wire feeding method, in-mold hanging rare earth metal method, ladle adding rare earth iron intermediate alloy method, etc., there are still a series of problems such as rare earth oxidation and burning, molten steel pollution and serious slag system damage. Therefore, the effective addition of rare earths is still a technical problem that restricts the development of rare earth steel. (3) Chromium and nickel are usually added in the molten steel alloying addition process using chromium-iron intermediate alloy and nickel-iron intermediate alloy. Among them, the density of chromium-iron alloy is 7.39-7.49g / cm 3 , melting point is 1600-1650℃; density of nickel-iron alloy is 8.07-8.58g / cm 3 , melting point is 1500-1510℃. The difference in density and melting point between ferrochrome and ferronickel and molten steel is not only not conducive to the uniformity of the composition of the molten steel, but also reduces the temperature of the molten steel and increases the smelting load. In addition, the application range of iron-based chromium and nickel intermediate alloys is narrow. They are only suitable for alloying additives for steel and cannot meet the addition process requirements of other non-iron-based alloys. (4) Rare earth metals are extremely easy to oxidize. Conventional rare earth additives are prone to severe oxidation during storage, which in turn causes contamination of the melt during process addition, seriously affecting the quality of the material. Summary of the invention

[0003] The purpose of the embodiments of the present invention is to provide a nickel-chromium-rare earth master alloy and a preparation method and additive thereof, which can obtain a density and melting point close to those of a nickel-based alloy or molten steel by reasonably adjusting the proportion of components, and can be evenly diffused and dissolved after addition, effectively solving the problems of oxidation and burning, unstable composition control, composition segregation and increased smelting load caused by differences in melting points and densities during the metallurgical addition process of nickel, chromium and rare earth in nickel-based alloys and steel.

[0004] To solve the above technical problems, a first aspect of an embodiment of the present invention provides a nickel-chromium-rare earth master alloy, comprising: nickel, chromium and rare earth metal;

[0005] The master alloy contains 5wt% to 90wt% nickel, 5wt% to 50wt% chromium, and 5wt% to 90wt% rare earth metal;

[0006] The density of the intermediate alloy is 7.7 g / cm 3 ~8.76g / cm 3 , melting point is 1354℃-1490℃, inclusion particle size is <30μm, and oxygen content is <150ppm.

[0007] Furthermore, the nickel content in the master alloy is 25wt% to 45wt%, the chromium content is 5wt% to 35wt%, and the rare earth metal content is 20wt% to 65wt%;

[0008] The density of the intermediate alloy is 7.86 g / cm 3 ~8.67g / cm 3 , melting point is 1367℃-1455℃.

[0009] Furthermore, the ratio of the sum of the mass of nickel and chromium in the master alloy to the mass of the rare earth metal is (1-4):1.

[0010] Furthermore, the mass ratio of nickel to chromium in the master alloy is (1-3):(1-3).

[0011] Furthermore, the rare earth metal includes at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, scandium and yttrium.

[0012] Furthermore, the rare earth metal includes at least one of lanthanum, cerium and yttrium.

[0013] Accordingly, a second aspect of an embodiment of the present invention provides a method for preparing a nickel-chromium-rare earth master alloy, which is used to prepare the nickel-chromium-rare earth master alloy, comprising the following steps:

[0014] The ingredients are proportioned according to the preset mass percentage, and nickel and chromium are loaded into the crucible;

[0015] The reaction furnace is evacuated and filled with a preset atmosphere to a preset pressure value, and the crucible is heated to make the metal temperature reach a preset temperature until the nickel and chromium are completely melted;

[0016] Add rare earth metals and refine for a preset time to obtain a nickel-chromium-rare earth master alloy solution;

[0017] gradually reducing the power to reduce the temperature of the nickel-chromium-rare earth master alloy solution to a second preset temperature and then pouring the solution into the mold, wherein the second preset temperature is higher than the melting point of the master alloy;

[0018] The alloy is cooled in the furnace under the protection of the furnace atmosphere and demoulded to obtain the nickel-chromium-rare earth master alloy.

[0019] Furthermore, the numerical range of the preset vacuum value is less than 0.1 Pa;

[0020] The preset atmosphere includes: argon;

[0021] The numerical range of the preset pressure value is 50000Pa~80000Pa;

[0022] The preset power is 10kw to 20kw;

[0023] The numerical range of the first preset temperature is 1350° C. to 1600° C.; and / or,

[0024] The value range of the preset time length is 10 minutes to 20 minutes.

[0025] Accordingly, a third aspect of an embodiment of the present invention provides an additive, including the above-mentioned nickel-chromium-rare earth master alloy, which is used in the production of rare earth steel or nickel-based alloy.

[0026] The above technical solution of the embodiment of the present invention has the following beneficial technical effects:

[0027] 1. Through the reasonable regulation of the component ratio, the master alloy can obtain a density and melting point close to that of nickel-based alloys or molten steel. Therefore, it can effectively improve the problems of oxidation and burning, poor composition uniformity, and unstable composition control caused by the differences in density and melting point of rare earth during the alloying process.

[0028] 2. Through the reasonable regulation of the component ratio, the intermediate alloy can obtain a density and melting point close to that of nickel-based alloys or molten steel. Therefore, it can effectively improve the problems of component segregation, unstable composition control, and increased smelting load caused by the differences in density and melting point of nickel and chromium during the alloying addition process.

[0029] 3. The co-introduction of chromium and nickel can not only form a dense chromium-rich oxide film and a composite chromium-nickel oxide protective layer, but also the nickel partially enriched at the bottom of the passivation film can further improve the stability of the passivation film, thereby significantly improving the oxidation resistance of the intermediate alloy and effectively improving the oxidation pollution problem of rare earth additives during storage and use.

[0030] 4. Through the reasonable regulation of the proportion of components, the nickel-chromium-rare earth master alloy can be used as an alloying additive for nickel-based alloys and molten steel at the same time. Compared with rare earth iron master alloys, chromium-iron master alloys, and nickel-iron master alloys in steel metallurgical processes, the nickel-chromium-rare earth master alloy has the advantage of a wide range of applications. It can not only be used as nickel, chromium, and rare earth additives for molten steel alloying, but also as an alloying additive for non-ferrous metals.

[0031] 5. The nickel-chromium-rare earth master alloy has uniform composition and wide applicability. It can be used as a rare earth, nickel and chromium additive for nickel-based high-temperature alloys with nickel, chromium and rare earth as the main alloying elements and special performance steels such as heat-resistant steel, stainless steel and weathering steel. The master alloy can be added in processes such as die casting or continuous casting to improve the high-temperature oxidation resistance, toughness and corrosion resistance of the above materials. The selected rare earth metal can be selected according to the types of elements in heat-resistant steel, stainless steel, weathering steel and nickel-based alloys, and will not bring new impurities.

[0032] 6. By reasonably adjusting the component ratio of the master alloy, the three elements of nickel, chromium and rare earth can be added at one time, the batching process of the alloy with nickel, chromium and rare earth as the main alloying elements can be optimized, and precise batching can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of a method for preparing a nickel-chromium-rare earth master alloy provided by an embodiment of the present invention;

[0034] Figure 2 It is a schematic diagram of the preparation process of the nickel-chromium-rare earth master alloy provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0036] The first aspect of the embodiment of the present invention provides a nickel-chromium-rare earth master alloy, comprising: nickel, chromium and rare earth metal; the nickel content of the master alloy is 5wt% to 90wt%, the chromium content is 5wt% to 50wt%, and the rare earth metal content is 5wt% to 90wt%; the master alloy density is 7.7g / cm 3 ~8.76g / cm 3 , melting point is 1354℃-1490℃, inclusion particle size is <30μm, and oxygen content is <150ppm.

[0037] The above nickel-chromium-rare earth master alloy improves the oxidation burning caused by density and melting point differences, poor composition uniformity, unstable composition control, and composition segregation and increased smelting load during the addition of nickel and chromium by rationally regulating the composition ratio. In addition, the dense and stable chromium-rich oxide film and composite chromium-nickel oxide protective layer formed on the alloy surface after the synergistic addition of chromium and nickel can improve the oxidation resistance of the rare earth master alloy and improve the oxidation pollution problem of rare earth additives during storage and use.

[0038] The present invention aims at the problems of oxidation burning, poor composition uniformity, unstable composition control and easy oxidation pollution during storage of low-density, low-melting-point and high-activity rare earth metals in the process of adding alloys to nickel-based alloys and molten steel, and the problems of poor composition uniformity and increased smelting load caused by density difference and melting point difference of nickel and chromium in the process of alloying and adding nickel-based alloys and molten steel. The melting point, density, component reaction and stability of oxide layer formation of rare earth, nickel and chromium are comprehensively analyzed, and the difficult problem of efficient addition of nickel, chromium and rare earth in the metallurgical preparation process of nickel-based alloy and steel can be effectively solved through reasonable component ratio regulation.

[0039] By rationally adjusting the proportion of components, the density and melting point close to those of nickel-based alloy or steel melt can be obtained, and after addition, the components can be uniformly diffused and dissolved, effectively solving the problems of oxidation burning, unstable component control, component segregation and increased smelting load caused by the difference in melting point and density of nickel, chromium and rare earth in the metallurgical addition process of nickel-based alloy and steel. At the same time, the simultaneous introduction of chromium and nickel can react on the surface of the alloy to form a dense and stable oxide protective layer, thereby effectively improving the oxidation problem of rare earth additives during storage and use. In addition, by adjusting the proportion of components, the master alloy can not only be applied to different types of nickel-based alloys and steel melts at the same time, but also can realize the one-time addition of three elements, optimize the batching process of alloys with nickel, chromium and rare earth as alloying elements, and realize precise batching. The nickel-chromium-rare earth master alloy prepared by the method has uniform composition and wide applicability, and can be used as nickel, chromium and rare earth additives for special performance steels such as nickel-based high-temperature alloys and heat-resistant steel, stainless steel and weathering steel. The preparation method of the master alloy provided by the present invention is simple, low in investment cost, and easy to promote and apply in industry.

[0040] Preferably, the nickel content in the master alloy is 25wt% to 45wt%, the chromium content is 5wt% to 35wt%, and the rare earth metal content is 20wt% to 65wt%; the density of the master alloy is 7.86g / cm 3 ~8.67g / cm 3 , melting point is 1367℃-1455℃.

[0041] Specifically, the ratio of the sum of the mass of nickel and chromium to the mass of the rare earth metal in the master alloy is (1-4):1.

[0042] Specifically, the mass ratio of nickel to chromium in the master alloy is (1-3):(1-3).

[0043] Optionally, the rare earth metal includes at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, scandium and yttrium. Preferably, the rare earth metal includes at least one of lanthanum, cerium and yttrium.

[0044] Accordingly, please refer to Figure 1 and Figure 2 A second aspect of an embodiment of the present invention provides a method for preparing a nickel-chromium-rare earth master alloy, which is used to prepare the nickel-chromium-rare earth master alloy, comprising the following steps:

[0045] Step S100, prepare materials according to preset mass percentages, and load nickel and chromium into the crucible. Cover the crucible and evacuate it to below the preset vacuum value, fill it with preset atmosphere to the preset pressure value and repeat the furnace cleaning 3 times, and power the furnace at the preset power.

[0046] Step S200, evacuating the reaction furnace and then filling it with a preset atmosphere to a preset pressure value, heating the crucible to make the metal temperature reach a first preset temperature until the nickel and chromium are completely melted.

[0047] Step S300, adding rare earth metals and refining for a preset time to obtain a nickel-chromium-rare earth master alloy solution.

[0048] Step S400, gradually reducing the power to reduce the temperature of the nickel-chromium-rare earth master alloy solution to a second preset temperature and then pouring the solution into a mold, wherein the second preset temperature is higher than the melting point of the master alloy.

[0049] Step S500, cooling in the furnace under the protection of the furnace atmosphere, and demoulding to obtain the nickel-chromium-rare earth master alloy.

[0050] Specifically, the numerical range of the preset vacuum value is less than 0.1Pa, and the preset atmosphere includes: argon; the numerical range of the preset pressure value is 50000Pa~80000Pa; the numerical range of the first preset temperature is 1350℃~1600℃; the preset power is 10kw~20kw; and / or, the numerical range of the preset time is 10min~20min.

[0051] The master alloy of the present invention can not only form a dense chromium-rich oxide film and a composite chromium-nickel oxide protective layer by the co-introduction of chromium and nickel, but also the nickel partially enriched at the bottom of the passivation film can further improve the stability of the passivation film, thereby significantly improving the oxidation resistance of the master alloy and effectively improving the oxidation pollution problem of rare earth additives during storage and use.

[0052] At the same time, by adjusting the proportion of components, the intermediate alloy can not only be used as an additive for nickel-based alloys and molten steel alloying, but its scope of application is completely superior to that of iron-based nickel, chromium and rare earth intermediate alloys. It can also realize the one-time addition of three elements, optimize the alloy proportioning process with nickel, chromium and rare earth as alloying elements, and achieve precise proportioning.

[0053] The present invention obtains the density, melting point and oxidation resistance weight gain test results of the nickel-chromium-rare earth master alloy under different nickel contents, different chromium contents and different rare earth elements and corresponding contents through experiments.

[0054] Furthermore, in the alloy oxidation weight gain test, each intermediate alloy was first processed by wire cutting into a size of Oxidation samples, 5 samples were prepared in each group, and they were polished with SiC sandpaper of No. 240 to 2000 in turn, then ultrasonically cleaned with acetone and alcohol, put into a drying oven for insulation for 1 hour, then taken out and put into a dryer for cooling to room temperature and then weighed; then the experimental corundum crucible was roasted and dried until constant weight; then a high-temperature oxidation resistance test was carried out in a high-temperature furnace, and the sample was loaded into the furnace after the furnace temperature was raised to 1000℃, and the static weight increase method was used for the selective oxidation test in the air medium. The crucible was taken out from the furnace every 20 hours of insulation, and weighed after cooling to room temperature. The cumulative oxidation time was 100 hours.

[0055] The preparation method of the nickel-chromium-rare earth master alloy is further described below with reference to several comparative examples and embodiments:

[0056] Embodiment 1:

[0057] A method for preparing a nickel-chromium-rare earth cerium master alloy of the present invention comprises the following steps:

[0058] Prepare materials according to the weight percentage of each element in the alloy: the weights of electrolytic chromium, electrolytic nickel, and rare earth metal cerium raw materials are 5.0kg, 14.39kg, and 5.31kg respectively; the purity of electrolytic nickel and chromium raw materials is 99.5%, and the rare earth metal is cerium, with a purity of 99.5%.

[0059] The above-mentioned electrolytic nickel and electrolytic chromium raw materials are placed in the alumina crucible of the vacuum induction melting furnace, and the rare earth metal cerium is placed in the charging bin. Magnesium oxide crucibles or calcium oxide crucibles can also be used instead of alumina crucibles. After filling the furnace with argon and washing it, evacuate it and then fill it with argon to 80000Pa. Slowly increase the power to make the crucible metal temperature reach 1430℃. After the nickel block and chromium block are completely melted, add rare earth metal cerium to the molten metal through the material trough and refine and keep warm for 10min. After the refining is completed, the alloy solution is poured into the mold and cooled with the furnace under the protection of argon atmosphere in the furnace. After 2h, demolding is carried out to obtain 24.9kg nickel-chromium-cerium intermediate alloy. The mold can be a cast iron mold or a stainless steel mold. The composition of the nickel-chromium-rare earth cerium intermediate alloy in this embodiment is: 20.1wt% chromium, 57.8wt% nickel and 22.1wt% cerium, with a density of 8.11g / cm3 and a melting point of 1360℃.

[0060] Embodiment 2:

[0061] A method for preparing a nickel-chromium-rare earth yttrium master alloy of the present invention comprises the following steps:

[0062] Prepare materials according to the weight percentage of each element in the alloy: the weights of electrolytic chromium, electrolytic nickel, and rare earth metal yttrium raw materials are 2.67kg, 16.9kg, and 4.74kg respectively; the purity of electrolytic nickel and chromium raw materials is 99.5%, and the rare earth metal is yttrium, with a purity of 99.5%.

[0063] The above-mentioned electrolytic nickel and electrolytic chromium raw materials are placed in the alumina crucible of the vacuum induction melting furnace, and the rare earth metal yttrium is placed in the charging bin. Magnesium oxide crucibles or calcium oxide crucibles can also be used instead of alumina crucibles. After vacuuming, argon is filled to 80000Pa. Slowly increase the power to make the crucible metal temperature reach 1600℃. After the nickel block and chromium block are completely melted, rare earth metal yttrium is added to the molten metal through the material trough and refined and kept warm for 15min. After the refining is completed, the alloy solution is poured into the mold and cooled with the furnace under the protection of argon atmosphere in the furnace. After 2h, demolding is performed to obtain 26.2kg nickel-chromium-yttrium intermediate alloy. The mold can be a cast iron mold or a stainless steel mold. The nickel-chromium-rare earth yttrium intermediate alloy of this embodiment is composed of: 10.2wt% chromium, 70.2wt% nickel and 19.6wt% yttrium, with a density of 7.85g / cm3 and a melting point of 1382℃.

[0064] Embodiment 3:

[0065] A method for preparing a nickel-chromium-rare earth gadolinium master alloy of the present invention comprises the following steps:

[0066] Prepare materials according to the weight percentage of each element in the alloy: the weights of electrolytic chromium, electrolytic nickel, and rare earth metal gadolinium raw materials are 1.21kg, 1.21kg, and 21.78kg respectively; the purity of electrolytic nickel and chromium raw materials is 99.5%; the rare earth metal is gadolinium, and its purity is 99.5%.

[0067] The above-mentioned electrolytic nickel and electrolytic chromium raw materials are placed in the alumina crucible of the vacuum induction melting furnace, and the rare earth metal gadolinium is placed in the charging bin. A magnesium oxide crucible or a calcium oxide crucible can also be used instead of an alumina crucible. After evacuation, argon is filled to 6000Pa, and the power is slowly increased to make the crucible metal temperature reach 1350°C. After the nickel block and the chromium block are completely melted, the rare earth metal gadolinium is added to the molten metal through the material trough and refined and kept warm for 20 minutes. After the refining is completed, the alloy solution is poured into the mold. Cool with the furnace under the protection of the argon atmosphere in the furnace, and demold after 2 hours to obtain 24.2kg of nickel-chromium-gadolinium intermediate alloy. The mold can be a cast iron mold or a stainless steel mold. The nickel-chromium-rare earth gadolinium intermediate alloy of this embodiment is composed of: 5wt% chromium, 5wt% nickel and 90wt% gadolinium, with a density of 7.91g / cm3 and a melting point of 1370°C.

[0068] Embodiment 4:

[0069] A method for preparing a nickel-chromium-rare earth praseodymium master alloy of the present invention comprises the following steps:

[0070] Prepare materials according to the weight percentage of each element in the alloy: the weights of electrolytic chromium, electrolytic nickel, and rare earth metal praseodymium are 12.9kg, 9.7kg, and 3.15kg respectively; the purity of electrolytic nickel and chromium raw materials is 99.5%; the rare earth metal is praseodymium, and its purity is 99.5%.

[0071] The above-mentioned electrolytic nickel and electrolytic chromium raw materials are placed in the alumina crucible of the vacuum induction melting furnace, and the rare earth metal praseodymium is placed in the material trough of the vacuum induction melting furnace. Magnesium oxide crucibles or calcium oxide crucibles can also be used instead of alumina crucibles. After evacuation, argon is filled to 5000Pa, and the power is slowly increased to make the crucible metal temperature reach 1560°C. After the nickel block and chromium block are completely melted, rare earth metal praseodymium is added to the molten metal through the material trough and refined and kept warm for 10 minutes. After the refining is completed, the alloy solution is poured into the mold. Cool with the furnace under the protection of argon atmosphere in the furnace, and demold after 2 hours to obtain 25.4kg nickel-chromium-praseodymium intermediate alloy. The mold can be a cast iron mold or a stainless steel mold. The nickel-chromium-rare earth praseodymium intermediate alloy of this embodiment is composed of: 50wt% chromium, 37.6wt% nickel and 12.4wt% praseodymium, with a density of 7.78g / cm3 and a melting point of 1395°C.

[0072] The raw material ratios of Examples 5 to 27 and Comparative Examples 1 to 6 are shown in Table 1, and their preparation methods are consistent with the above-mentioned preparation methods.

[0073] Table 1

[0074]

[0075]

[0076] In order to compare the differences in density, melting point and oxidation resistance between the nickel-chromium-rare earth master alloy of the present invention and conventional master alloys, as well as the uniformity and yield of each element composition after adding the nickel-chromium-rare earth master alloy to steel or nickel-based alloys, the present invention prepared 27 types of nickel-chromium-rare earth master alloys and comparative master alloys, and tested their density, melting point and oxidation resistance.

[0077] From the melting point, density and oxidation resistance of each master alloy in Table 1, it can be seen that: through reasonable component ratio regulation, the nickel-chromium-rare earth master alloy provided by the present invention can obtain a density and melting point close to that of a nickel-based alloy or a steel solution, while the master alloy shown in the comparative example is difficult to simultaneously achieve a density and melting point close to that of a nickel-based alloy and steel through component adjustment. At the same time, the oxidation resistance of Ni-Cr-Ce shown in Example 1 is better than that of the master alloys to which Cr or Ni is added alone in Comparative Example 1 and Comparative Example 2, because the co-introduction of chromium and nickel can not only form a dense chromium-rich oxide film and a composite chromium-nickel oxide protective layer, but also the nickel partially enriched at the bottom of the passivation film can further improve the stability of the passivation film, thereby significantly improving the oxidation resistance of the master alloy. In addition, its oxidation resistance is also much better than that of the Ce-Fe alloy in the comparative example. In addition, the oxidation resistance of Ni-Cr-Y shown in Example 2 is also better than that of the Ni-Y, Cr-Y and Fe-Y alloys shown in Comparative Examples 4-6. Therefore, the nickel-chromium-rare earth can effectively improve the oxidation pollution problem of rare earth additives during storage and use.

[0078] It can be known from the above embodiments and comparative examples that:

[0079] The nickel-chromium-rare earth cerium master alloy in Example 1, the chromium-cerium master alloy in Comparative Example 2, and elemental chromium + elemental cerium were used to prepare GH4169 nickel-based high-temperature alloy in a medium-frequency induction furnace. The addition of the nickel-chromium-rare earth cerium master alloy provided by the present invention significantly improves the yield and composition uniformity of rare earth cerium and chromium. The comparison results are shown in Table 2.

[0080] Table 2

[0081]

[0082] The nickel-chromium-rare earth yttrium master alloy in Example 2, the yttrium-chromium master alloy in Comparative Example 5, and elemental chromium + elemental yttrium were used to prepare GH4169 nickel-based high-temperature alloy. The addition of the nickel-chromium-rare earth yttrium master alloy provided by the present invention significantly improves the yield and composition uniformity of rare earth yttrium and chromium. The comparison results are shown in Table 3.

[0083] Table 3

[0084]

[0085] 06Cr23Ni13 high nickel austenitic stainless steel was prepared using the nickel-chromium-rare earth cerium master alloy in Example 1 and the cerium-iron master alloy + chromium-iron alloy + nickel-iron alloy in Comparative Example 8. The addition of the nickel-chromium-rare earth cerium master alloy provided by the present invention significantly improves the yield and composition uniformity of rare earth cerium, chromium and nickel. The comparison results are shown in Table 4.

[0086] Table 4

[0087]

[0088] 06Cr23Ni13 high nickel austenitic stainless steel was prepared using the nickel-chromium-rare earth yttrium master alloy in Example 2 and the yttrium-iron master alloy + chromium-iron alloy + nickel-iron alloy in Comparative Example 6. The addition of the nickel-chromium-rare earth cerium master alloy provided by the present invention significantly improves the yield and composition uniformity of rare earth yttrium, chromium and nickel. The comparison results are shown in Table 5.

[0089] Table 5

[0090]

[0091] Accordingly, a third aspect of an embodiment of the present invention provides an additive, including the above-mentioned nickel-chromium-rare earth master alloy, which is used in the production of rare earth steel or nickel-based alloy.

[0092] Specifically, the rare earth steel and nickel-based alloy include: die-cast or continuous-cast ordinary steel, structural steel, tool steel, special performance steel and / or high-temperature alloy, etc.

[0093] The embodiment of the present invention is intended to protect a nickel-chromium-rare earth master alloy and its preparation method and additives. The master alloy comprises: nickel, chromium and rare earth metal; the nickel content in the master alloy is 5wt% to 90wt%, the chromium content is 5wt% to 50wt%, and the rare earth metal content is 5wt% to 90wt%; the master alloy density is 7.7g / cm 3 ~8.76g / cm 3 , melting point is 1354℃-1490℃, inclusion size is less than 30μm, oxygen content is less than 150ppm. The above technical solution has the following effects:

[0094] By rationally adjusting the proportion of components, a density and melting point close to those of nickel-based alloys or molten steel can be obtained, which can diffuse and dissolve evenly after addition, effectively solving the problems of oxidation and burning, unstable composition control, composition segregation and increased smelting load caused by differences in melting points and densities during the metallurgical addition process of nickel, chromium and rare earth in nickel-based alloys and steel.

[0095] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A nickel-chromium-rare earth master alloy, It is characterized in that include: nickel, chromium and rare earth metals; The master alloy contains 5wt% to 90wt% nickel, 5wt% to 50wt% chromium, and 5wt% to 90wt% rare earth metal; The density of the intermediate alloy is 7.7 g / cm 3 ~8.76g / cm 3 , melting point is 1354℃-1490℃, inclusion particle size is <30μm, and oxygen content is <150ppm.

2. The nickel-chromium-rare earth master alloy according to claim 1, It is characterized in that The master alloy contains 25wt% to 45wt% nickel, 5wt% to 35wt% chromium, and 20wt% to 65wt% rare earth metal; The density of the intermediate alloy is 7.86 g / cm 3 ~8.67g / cm 3 , melting point is 1367℃-1455℃.

3. The nickel-chromium-rare earth master alloy according to claim 2, It is characterized in that The ratio of the sum of the mass of nickel and chromium in the master alloy to the mass of the rare earth metal is (1-4):

1.

4. The nickel-chromium-rare earth master alloy according to claim 3, It is characterized in that The mass ratio of nickel to chromium in the master alloy is (1-3):(1-3).

5. The nickel-chromium-rare earth master alloy according to any one of claims 1 to 4, It is characterized in that The rare earth metal includes at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, scandium and yttrium.

6. The nickel-chromium-rare earth master alloy according to claim 5, It is characterized in that The rare earth metal includes at least one of lanthanum, cerium and yttrium.

7. A method for preparing a nickel-chromium-rare earth master alloy, It is characterized in that The method for preparing the nickel-chromium-rare earth master alloy as claimed in any one of claims 1 to 6 comprises the following steps: The ingredients are proportioned according to the preset mass percentage, and nickel and chromium are loaded into the crucible; Close the cover and evacuate the furnace to below the preset vacuum value, fill it with a preset atmosphere to a preset pressure value, and repeat the furnace cleaning three times; after evacuating the reaction furnace, fill it with a preset atmosphere to a preset pressure value, heat the crucible so that the metal temperature reaches a first preset temperature, and until the nickel and chromium are completely melted; Add rare earth metals and refine for a preset time to obtain a nickel-chromium-rare earth master alloy solution; gradually reducing the power to reduce the temperature of the nickel-chromium-rare earth master alloy solution to a second preset temperature and then pouring the solution into the mold, wherein the second preset temperature is higher than the melting point of the master alloy; The alloy is cooled in the furnace under the protection of the furnace atmosphere and demoulded to obtain the nickel-chromium-rare earth master alloy.

8. The method for preparing the nickel-chromium-rare earth master alloy according to claim 7, It is characterized in that The numerical range of the preset vacuum value is less than 0.1 Pa; The preset atmosphere includes: argon; The numerical range of the preset pressure value is 50000Pa~80000Pa; The preset power is 10kw to 20kw; The numerical range of the first preset temperature is 1350° C. to 1600° C.; and / or, The value range of the preset time length is 10 minutes to 20 minutes.

9. An additive, It is characterized in that The nickel-chromium-rare earth master alloy comprises any one of claims 1 to 6 and is used for producing rare earth steel or nickel-based alloy.

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