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CN-122012959-A - Method for preparing ultrahigh-purity invar alloy ingot based on forging diameter change

CN122012959ACN 122012959 ACN122012959 ACN 122012959ACN-122012959-A

Abstract

The invention discloses a method for preparing an ultrahigh-purity invar alloy ingot based on forging diameter change, which comprises the following steps of first step of vacuum electron beam melting to form an ingot, second step of forging diameter change, third step of vacuum consumable remelting, wherein the vacuum electron beam cold bed melting, the forging diameter change and the vacuum consumable remelting form a short continuous process, and the method has the advantages of large size, high purity, high grain size, uniform and compact structure, few defects and the like through optimizing parameters.

Inventors

  • WU JINGHUI
  • WANG MINJUN
  • DU QUANGUO
  • HU YAOYANG
  • YANG ZHIJUN
  • ZHONG XIANG

Assignees

  • 宁波创润新材料有限公司

Dates

Publication Date
20260512
Application Date
20260310

Claims (7)

  1. 1. The method for preparing the ultra-high purity invar alloy cast ingot based on forging diameter change is characterized by comprising the following steps of: firstly, smelting and forming an ingot by using a vacuum electron beam, adding raw materials with a required proportion of the invar alloy ingot into a furnace for smelting, melting a blank by using a first electron gun, and refining alloy melt melted in a crucible by using a second electron gun; Secondly, forging and diameter changing, namely preserving the heat of the cast ingot obtained in the first step for 4-8 hours at 1100-1250 ℃, and then performing upsetting treatment to the required size, wherein the initial forging temperature is more than or equal to 1050 ℃, and the final forging temperature is more than or equal to 950 ℃; And thirdly, remelting in a vacuum consumable manner, polishing the surface of the cast ingot forged in the second step, adding the cast ingot into a furnace for smelting, cooling the cast ingot with the furnace for at least 7 hours under high vacuum after smelting, and discharging the cast ingot after the surface temperature of the cast ingot is reduced to below 200 ℃.
  2. 2. The method for preparing the ultra-high purity invar alloy ingot based on forging diameter change as set forth in claim 1, wherein in the first step, the vacuum degree in the furnace is 4.5-5.5X10 -3 Pa, the pressure rise rate in the furnace is less than 1Pa/h, the first electron gun is used for smelting 300-320KW, the second electron gun is used for smelting 250-270KW, the smelting temperature is 1500-1600 ℃, the smelting rate is 9-11kg/min, the smelting time is 3-4h, and the ingot is discharged after the smelting is finished and naturally cooled for at least 4 h.
  3. 3. The method for preparing the invar alloy ingot with the ultra-high purity based on forging and diameter changing according to claim 2, wherein the invar alloy raw materials in the first step are mixed with 70 percent of Fe and 30 percent of Ni, and the mixture is prepared by an electrolytic iron plate and an electrolytic nickel plate with the purity of more than 99.99 percent.
  4. 4. The method for preparing the ultra-high purity invar alloy ingot based on forging diameter change, as set forth in claim 1, wherein in the second step, upsetting is firstly carried out at 1050-1150 ℃ along the axial direction, the upsetting deformation is 65-80%, then the furnace is returned to 980-1130 ℃ for radial drawing, the drawing deformation is 20-40%, the furnace is returned to 980-1130 ℃ for secondary axial upsetting, the upsetting deformation is 50-70%, the furnace is returned to 980-1130 ℃ for secondary radial drawing, and the drawing deformation is 40-55%.
  5. 5. A method for producing an ultra-high purity invar alloy ingot based on forging modification according to claim 1, wherein in the second step, the temperature is raised to 1200 ℃ at a rate of <100 ℃ per hour under the protection of inert gas and kept for 6 hours, and immediately after the completion of forging, the ingot is transferred into a hood-cooled furnace and cooled to 150 ℃ at a rate of <40 ℃ per hour and discharged from the furnace.
  6. 6. The method for preparing the ultra-high purity invar alloy ingot based on forging diameter change, which is characterized in that in the third step, the smelting current is linearly increased to 9+/-0.3 kA within 5min after a molten pool is stabilized during smelting, steady-state smelting is carried out at a constant smelting speed, the vacuum degree is less than 0.5Pa, the smelting current is linearly decreased to 2kA in 8-11 stages within 55+/-5 min at the end of smelting, after remelting, the ingot is cooled for at least 7h along with the furnace in a furnace with the vacuum degree less than or equal to 1Pa, and the ingot is discharged after the surface temperature is reduced to 200 ℃.
  7. 7. The method for producing an ultra-high purity invar alloy ingot based on forging and diameter modification according to claim 1, wherein in the third step, after the ingot is put into a crucible, vacuum is first applied to a vacuum degree of <0.1Pa, and then an arcing current of 6kA is applied between an electrode and a bottom homogeneous arc starting material and maintained for 6min.

Description

Method for preparing ultrahigh-purity invar alloy ingot based on forging diameter change Technical Field The invention relates to the technical field of alloys, in particular to a method for preparing an ultrahigh-purity invar alloy ingot based on forging and diameter changing. Background Invar is an iron-nickel based precision alloy with an ultra-low coefficient of thermal expansion near room temperature, whose typical composition is 36% nickel (balance iron and small amounts of other elements), and is therefore also known as Fe-36Ni alloy. The core properties of the alloy are very low average coefficients of thermal expansion, typically about 1.2x10 -6/°c, over a temperature range of-20 ℃ to 100 ℃, and only about one tenth of that of conventional steels, due to their special cancellation effects of ferromagnetism and lattice expansion. Invar is widely used in the fields of aerospace (such as satellite structures, gyroscopes), precision instruments (such as optical platforms, laser cavities), electronic packaging, and critical sealing materials for Liquefied Natural Gas (LNG) carriers, due to its excellent dimensional stability. The prior art has the defects that the invar alloy is easy to repeatedly contact with a crucible of refractory materials and slag in the preparation process of the invar alloy ingot, so that the purity of the ingot is reduced, the tissue uniformity is poor, the invar alloy with high quality is difficult to stably obtain, and the invar alloy is required to be improved. Disclosure of Invention In order to solve at least one technical defect, the invention provides the following technical scheme: The application discloses a method for preparing an ultrahigh-purity invar alloy ingot based on forging and diameter changing, which comprises the following steps: firstly, smelting and forming an ingot by using a vacuum electron beam, adding raw materials with a required proportion of the invar alloy ingot into a furnace for smelting, melting a blank by using a first electron gun, and refining alloy melt melted in a crucible by using a second electron gun; Secondly, forging and diameter changing, namely preserving the heat of the cast ingot obtained in the first step for 4-8 hours at 1100-1250 ℃, and then performing upsetting treatment to the required size, wherein the initial forging temperature is more than or equal to 1050 ℃, and the final forging temperature is more than or equal to 950 ℃; And thirdly, remelting in a vacuum consumable manner, polishing the surface of the cast ingot forged in the second step, adding the cast ingot into a furnace for smelting, cooling the cast ingot with the furnace for at least 7 hours under high vacuum after smelting, and discharging the cast ingot after the surface temperature of the cast ingot is reduced to below 200 ℃. Further, in the first step, the vacuum degree in the furnace is 4.5-5.5X10 -3 Pa, the pressure rise rate in the furnace is less than 1Pa/h, the first electron gun is used for smelting at 300-320KW, the second electron gun is used for smelting at 250-270KW, the smelting temperature is 1500-1600 ℃, the smelting rate is 9-11kg/min, the smelting time is 3-4h, and the ingot is discharged after the smelting is finished and naturally cooled for at least 4 h. Further, in the first step, the invar alloy raw materials are mixed into the mixture of 70% of Fe and 30% of Ni, and the mixture is mixed into the electrolytic iron plate and the electrolytic nickel plate with the purity of more than 99.99%. Further, in the second step, upsetting is firstly carried out at 1050-1150 ℃ along the axial direction, the upsetting deformation is 65-80%, then the furnace is returned to 980-1130 ℃ for radial drawing, the drawing deformation is 20-40%, the furnace is returned to 980-1130 ℃ for secondary axial upsetting, the upsetting deformation is 50-70%, the furnace is returned to 980-1130 ℃ for secondary radial drawing, and the drawing deformation is 40-55%. Further, in the second step, the temperature is raised to 1200 ℃ at a rate of <100 ℃ per hour under the protection of inert gas and kept for 6 hours, and immediately after the forging is completed, the mixture is transferred into a cover cooling furnace and cooled to 150 ℃ at a rate of <40 ℃ per hour and discharged from the furnace. In the third step, after the melting pool is stabilized, the melting current is linearly increased to 9+/-0.3 kA within 5min and is subjected to steady-state melting at a constant melting speed, the vacuum degree is less than 0.5Pa, the melting current is linearly decreased to 2kA in 8-11 stages within 55+/-5 min at the end of melting, after the remelting is finished, the cast ingot is cooled for at least 7h along with the furnace in the furnace with the vacuum degree of less than or equal to 1Pa, and the cast ingot is discharged after the surface temperature is reduced to 200 ℃. Further, in the third step, after the ingot was charged into the crucible, vacuum was first applied to