Method for controlling rolling of plate of nickel-based wrought superalloy resistant to molten salt corrosion

Abstract

The application relates to an alloy plate processing technology and discloses a molten salt corrosion resistant nickel-based deformed high-temperature alloy plate organization control rolling method, which solves the problems of difficult deformation and poor organization uniformity of high-tungsten high-temperature alloy plates. The method comprises the following steps: preparing raw materials according to the standard proportion of each element of the alloy, adopting a double smelting process, stirring in smelting, and obtaining a composition-uniform ingot; uniformly annealing the ingot at a temperature not lower than 1200 DEG C in steps; forging the annealed ingot into a 50-60mm plate blank; machining the plate blank after forging, and the surface roughness of the machined plate blank ranges from 30 to 60 microns; heating the plate blank obtained through machining to 950-1200 DEG C, and hot rolling the plate blank for multiple times to 10-20mm; after surface grinding, cold rolling the plate blank for multiple times to 4-6mm; adopting a heat treatment furnace to perform solid solution treatment on the alloy plate obtained through rolling, the solid solution treatment temperature is 1200+ / -10 DEG C, the holding time is 30-90 minutes, and the alloy plate is cooled through water quenching after heat treatment.

Description

Technical Field

[0001] This application relates to alloy sheet processing technology, and in particular to processing technology for nickel-based deformable high-temperature alloy sheets resistant to molten salt corrosion. Background Technology

[0002] This section is intended to provide background or context for the embodiments of this application as set forth in the claims. The description herein is not intended to imply that it is prior art that has been disclosed, simply because it is included in this section.

[0003] With the surge in my country's energy demand and the implementation of the "dual carbon" target, clean, safe, and efficient advanced nuclear and solar energy are among the best ways to solve my country's energy problems and carbon emission targets. Vigorously developing nuclear and solar energy is also an important direction for my country's future energy structure adjustment and optimization. Halogen molten salts (fluoride salts, chloride salts), as a high-heat-capacity and high-thermal-conductivity heat storage and transfer medium, can be applied to molten salt reactors and concentrated solar thermal power generation devices, and are favored by countries worldwide due to their high efficiency, economy, and sustainable development advantages. Furthermore, the structural materials for pressure vessels and heat exchangers used in high-temperature molten salt environments are required to operate stably under extreme conditions such as high temperature and strong corrosion for extended periods.

[0004] On the other hand, to achieve higher-efficiency energy conversion such as high-temperature hydrogen production, the outlet temperature of molten salt reactors needs to reach above 800 ℃. However, currently, no commercially available alloys can meet the performance requirements of structural alloys for 800 ℃ molten salt reactors. The most promising structural alloy for 800 ℃ molten salt reactors is a new type of molten salt corrosion-resistant nickel-based wrought high-temperature alloy, Ni-(26-28W)-6Cr (GH3539 alloy), jointly developed by the Shanghai Institute of Applied Physics and the Institute of Metal Research, Chinese Academy of Sciences. This is a Ni-W-Cr solid solution strengthened wrought alloy with a W content as high as 24%-28%, belonging to difficult-to-deform high-temperature alloys. During hot rolling, uniform deformation must be maintained to prevent cracking and material scrapping. At the same time, it is also necessary to improve the uniformity of the microstructure, refine the grains, and improve the material grade. Therefore, controlling the microstructure evolution of alloy plates and ultimately obtaining qualified plates with uniform and fine grains by combining smelting processes, hot rolling and cold rolling processes, and heat treatment processes is technically challenging and is one of the key issues restricting the development of molten salt reactors. Summary of the Invention

[0005] The purpose of this application is to provide a method for controlling the microstructure of nickel-based deformable high-temperature alloy plates resistant to molten salt corrosion, which solves the problems of difficult deformation and poor microstructure uniformity of high-tungsten high-temperature alloy plates.

[0006] This application discloses a method for controlling the microstructure of nickel-based deformable high-temperature alloy plates resistant to molten salt corrosion, comprising the following steps:

[0007] 1) Prepare raw materials according to the standard proportions of each element in the alloy, and use a double melting process with stirring during smelting to obtain a uniformly composed ingot.

[0008] 2) The ingot is subjected to step-by-step homogenization annealing at a temperature not lower than 1200℃;

[0009] 3) Forge the annealed ingot into 50-60mm slabs, wherein the forging heating temperature is 1180±20℃ and the final forging temperature is not lower than 900℃;

[0010] 4) The forged slab is machined to achieve a surface roughness of 30-60 μm.

[0011] 5) Heat the machined slab to 950-1200℃ and hot roll it multiple times to 10-20mm; after surface grinding, cold roll it multiple times to 4-6mm.

[0012] 6) The rolled alloy sheet is solution treated in a heat treatment furnace at a temperature of 1200±10℃ and a holding time of 30-90 minutes. After heat treatment, it is cooled by water quenching.

[0013] In a preferred embodiment, in step 1), the alloy is formulated in the following standard weight percentages: Cr: 6.0-8.0%, W: 24.0-28.0%, Fe: 0.5-0.55%, Mn: 0.5-0.8%, Si: 0.1-0.4%, C: 0.025-0.08%, Mo: 0-1.0%, Ti: 0-0.2%, Ni: balance.

[0014] In a preferred embodiment, the alloy does not contain Zr.

[0015] In a preferred embodiment, in step 1), the alloy is formulated in the following standard weight percentages: Cr: 6.0-8.0%, W: 24.0-28.0%, Fe: 0.5-0.55%, Mn: 0.5-0.8%, Si: 0.1-0.4%, C: 0.025-0.08%, Mo: 0-1.0%, Ti: 0-0.2%, Zr: 0-0.1%, Ni: balance; wherein, the addition of Zr refines the alloy grains and increases the grain boundary strength, which is more conducive to microstructure control and large deformation rolling.

[0016] In a preferred embodiment, the dual-melting process includes vacuum induction melting and vacuum consumable melting, and electromagnetic stirring is used during the melting process. The temperature of the alloy liquid in the vacuum induction melting stage is controlled within the range of 1550±20℃, and the melting time is 15-20 minutes. After the melting is completed, the casting temperature in the casting stage is controlled within the range of 1450±20℃.

[0017] In a preferred embodiment, step 2) further includes: holding the ingot at 1200-1250°C for 5 hours, and then raising the temperature to 1200-1250°C and holding it for 10-20 hours.

[0018] In a preferred embodiment, the multi-fire hot rolling further includes:

[0019] One-fire rolling: The slab obtained from the ingot processing is heated to 950-1200℃, and the holding time is calculated at 0.5-1.0mm / min. The number of rolling passes is 5-10, the total deformation is 40%-50%, and then the material is divided.

[0020] Second rolling: The slab after material division is heated to 950-1200℃, and the holding time is calculated at 0.4-0.8mm / min. The number of rolling passes is 4-6, and the total deformation is 35%-50%. Then the material is divided.

[0021] Three-stage rolling: The slab after material division is heated to 950-1200℃, and the holding time is calculated at 0.5-1.0 mm / minute. The number of rolling passes is 4-6, and the total deformation is 45%-60%.

[0022] In a preferred embodiment, if the thickness of the finished sheet is greater than or equal to 4 mm, the method further includes:

[0023] After the three-stage rolling process, the material is divided and cold-rolled: the number of rolling passes does not exceed 5, and the total deformation is not less than 45%.

[0024] In a preferred embodiment, during the solution treatment, the heating rate of the plate is 0.5-1.0 mm / min.

[0025] In a preferred embodiment, after step 4), the following steps are also included:

[0026] Ultrasonic testing is performed on the slabs obtained from machining.

[0027] In the embodiments of this application, by controlling the entire process, including high-temperature alloy purification smelting, step-by-step high-temperature annealing, microstructure control of large deformation plate rolling, and plate surface process control, the problems of difficult deformation and poor microstructure uniformity of high-tungsten high-temperature alloy plates are solved, the material yield and mechanical properties are improved, and high-temperature alloy plates with uniform microstructure and stable performance are prepared, which can be used in components such as molten salt reactor pressure vessels and heat exchangers.

[0028] In addition, the rolling process that combines multi-stage hot rolling with cold rolling can effectively improve the microstructure of alloy plates, resulting in thin plates with high purity, fine grains, and uniform microstructure, which meets the requirements for use in molten salt stress vessels.

[0029] The various technical features disclosed in the invention description, the various technical features disclosed in the embodiments and examples below, and the various technical features disclosed in the accompanying drawings can be freely combined to form various new technical solutions (all of which should be considered as recorded in this specification), unless such combination of technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed. Features C and D are equivalent technical means that serve the same function, and technically only one needs to be used; it is impossible to use both simultaneously. Feature E can be technically combined with feature C. Therefore, the solution A+B+C+D should not be considered as recorded because it is technically infeasible, while the solution A+B+C+E should be considered as recorded. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a method for controlling the microstructure of a nickel-based deformable high-temperature alloy sheet resistant to molten salt corrosion according to an embodiment of this application;

[0031] Figure 2 This is a microstructure diagram of the high-temperature alloy sheet prepared in Example 1 of this application;

[0032] Figure 3 This is a microstructure diagram of the high-temperature alloy sheet prepared in Example 5 of this application. Detailed Implementation

[0033] In the following description, many technical details are presented to help the reader better understand this application. However, those skilled in the art will understand that the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0034] This application provides a method for controlled rolling of nickel-based deformable superalloy plates resistant to molten salt corrosion. The alloy has an austenitic structure, exhibiting high mechanical properties and structural stability, as well as excellent resistance to molten salt corrosion, demonstrating superior service performance at operating temperatures of 800-850℃. Furthermore, due to the high content of the solid solution element W in the alloy, it exhibits significant deformation resistance, placing high demands on the design of the processing technology during profile fabrication.

[0035] In one embodiment, the chemical composition (by weight percentage) of the suitable molten salt corrosion resistant nickel-based wrought superalloy is as follows: Cr: 6.0-8.0%, W: 24.0-28.0%, Fe: 0.5-0.55%, Mn: 0.5-0.8%, Si: 0.1-0.4%, C: 0.025-0.08%, Mo: 0-1.0%, Ti: 0-0.2%, Ni: balance. Specifically, this superalloy does not contain the trace element Zr.

[0036] In one embodiment, the chemical composition (by weight percentage) of the suitable molten salt corrosion resistant nickel-based wrought superalloy is as follows: Cr: 6.0-8.0%, W: 24.0-28.0%, Fe: 0.5-0.55%, Mn: 0.5-0.8%, Si: 0.1-0.4%, C: 0.025-0.08%, Mo: 0-1.0%, Ti: 0-0.2%, Zr: 0-0.1%, Ni: balance. When trace element Zr is added to this alloy, the alloy grains are refined, the grain boundary strength is improved, which is more conducive to microstructure control and large deformation rolling.

[0037] In one embodiment, the main process of the plate microstructure control rolling method involving the above-mentioned high-temperature alloy is to use vacuum induction melting + electroslag remelting double melting to cast a master alloy ingot with the required chemical composition, to prepare a slab by forging, and then to perform multi-stage microstructure control hot rolling and large deformation cold rolling on the slab. Subsequently, the rolled plate is subjected to solution treatment to obtain the high-temperature alloy plate.

[0038] Specifically, the steps include the following:

[0039] Step 1) Ingot preparation: After melting and refining the alloy raw materials, the alloy obtained from melting and refining is cast into electrodes. The electrode rods are then subjected to electroslag remelting and cast into alloy ingots.

[0040] Step 2) Homogenization treatment: Homogenize the alloy ingot in segments at different temperatures within the range of 1200-1300 ℃ for more than 15 hours.

[0041] Preferably, the homogenization treatment temperature is 1200-1300 ℃, and the homogenization treatment duration is greater than 15 hours; preferably, the homogenization treatment temperature includes multiple temperature ranges; wherein the homogenization temperature of the previous temperature range is lower than that of the next temperature range; preferably, the temperature of the first temperature range is not lower than 1200 ℃, and the temperature of the final temperature range is not higher than 1300 ℃; preferably, the homogenization treatment duration does not exceed 25 hours.

[0042] Step 3) Forging slab: The homogenized master alloy ingot is forged into a slab with a thickness of 50-60 mm. The forging heating temperature is 1180±20 ℃, and the final forging temperature is not lower than 900 ℃.

[0043] Step 4) Machining and Ultrasonic Testing: The forged slab is machined to achieve a surface roughness of 30-60 μm. Optionally, the machined slab is subjected to ultrasonic testing to ensure that there are no metallurgical defects such as delamination or folding inside the slab.

[0044] Step 5) Rolling: The machined alloy slab is heated to 950-1200℃ and hot rolled multiple times to 10-20 mm; after surface grinding, it is cold rolled multiple times to 4-6 mm.

[0045] Preferably, the hot rolling process involves at least two hot rolling passes; preferably, the final hot rolling temperature is at least 950°C.

[0046] Step 6) Heat treatment: The rolled plate is heat treated at 1200±10 ℃ for more than 30 minutes and then water cooled to obtain a fine-grained austenitic high-temperature alloy plate resistant to molten salt corrosion.

[0047] Preferably, the heat treatment holding time does not exceed 90 minutes.

[0048] The present application will be further described in detail below through specific embodiments:

[0049] The following examples and comparative examples illustrate the preparation of a nickel-based wrought high-temperature alloy sheet resistant to molten salt corrosion. The microstructure of the prepared high-temperature alloy sheet was observed using an Axiovert 200 MAT optical microscope, and its grain size was analyzed.

[0050] Example 1

[0051] A method for controlling the microstructure of nickel-based deformable superalloy plates resistant to molten salt corrosion includes the following steps:

[0052] 1) Ingot Preparation: The alloy raw materials are added to a high-frequency vacuum induction furnace at a melting temperature of 1500 ℃ and a vacuum degree of 0.5×10-2 Pa. After the raw materials are completely melted, they are refined at 1550℃ for 15 minutes. Then, inert gas is introduced and the alloy liquid is poured into ingots, with the pouring temperature controlled within the range of 1450±20 ℃. After the vacuum-melted ingot cools, the ingot, after the riser is removed and polished, is placed in an electroslag remelting equipment as an electrode. After three steps of remelting operations—arc initiation, flux melting, and capping and feeding—the refined alloy ingot obtained by electroslag remelting is obtained. Specifically, the alloy components by weight percentage are: C 0.05%, Cr 6.0%, W 25.0%, Fe 0.5%, Mn 0.5%, Si 0.1%, Mo 0.5%, Ti 0.2%, with the balance being Ni.

[0053] 2) Homogenization treatment: The alloy ingot is subjected to the first homogenization treatment at 1230 ℃ for 5 hours in a resistance furnace, followed by the second homogenization treatment at 1270 ℃ for 15 hours.

[0054] 3) Forging slab: The homogenized master alloy ingot is forged into a slab with a thickness of 55 mm, wherein the forging heating temperature is 1180 ℃ and the final forging temperature is 930 ℃.

[0055] 4) Machining and ultrasonic testing: The forged slab is machined to achieve a surface roughness of 30-60 μm. Then, ultrasonic testing is performed to ensure that there are no metallurgical defects such as delamination or folding inside the slab.

[0056] 5) Controlled Rolling: The machined alloy slab is heated and subjected to multiple hot rolling passes; after surface grinding, it undergoes multiple cold rolling passes to a thickness of 4-6 mm. Specifically, the first hot rolling pass has an initial rolling temperature of 1150℃, 5 rolling passes, a total deformation of 40%, and a final rolling temperature control range of 1000℃, followed by material separation; the second hot rolling pass has an initial rolling temperature of 1150℃, 5 rolling passes, a total deformation of 40%, and a final rolling temperature control range of 1000℃, followed by material separation; the third hot rolling pass has an initial rolling temperature of 1180℃, 5 rolling passes, a total deformation of 50%, and a final rolling temperature control range of 1050℃, followed by material separation. The cold rolling passes after the third hot rolling pass do not exceed 5, and the total deformation is not less than 45%.

[0057] 6) Solution treatment: The alloy sheet after microstructure control rolling is solution treated in a high-temperature precision heat treatment furnace at a temperature of 1200 ℃ and a holding time of 60 minutes. After heat treatment, it is cooled to room temperature by water to obtain nickel-based deformable high-temperature alloy sheet resistant to molten salt corrosion.

[0058] The microstructure diagram of the high-temperature alloy sheet prepared in Example 1 is shown below. Figure 2 As shown.

[0059] Example 2

[0060] A method for controlling the microstructure of nickel-based deformable superalloy plates resistant to molten salt corrosion includes the following steps:

[0061] 1) Ingot Preparation: The alloy raw materials are added to a high-frequency vacuum induction furnace at a melting temperature of 1500 ℃ and a vacuum degree of 0.5×10-2 Pa. After the raw materials are completely melted, they are refined at 1550 ℃ for 15 minutes. Then, inert gas is introduced and the alloy liquid is poured into ingots, with the pouring temperature controlled within the range of 1450±20 ℃. After the vacuum-melted ingot cools, the ingot, after the riser is removed and polished, is placed in an electroslag remelting equipment as an electrode. After three steps of remelting operations—arc initiation, flux melting, and capping and feeding—the refined alloy ingot obtained by electroslag remelting is obtained. Specifically, the alloy components by weight percentage are: C 0.05%, Cr 6.0%, W 25.0%, Fe 0.5%, Mn 0.5%, Si 0.1%, Mo 0.5%, Ti 0.2%, with the balance being Ni.

[0062] 2) Homogenization treatment: The alloy ingot is subjected to the first homogenization treatment at 1230 ℃ for 5 hours in a resistance furnace, followed by the second homogenization treatment at 1270 ℃ for 15 hours.

[0063] 3) Forging slab: The homogenized master alloy ingot is forged into a slab with a thickness of 60 mm, wherein the forging heating temperature is 1180 ℃ and the final forging temperature is 930 ℃.

[0064] 4) Machining and ultrasonic testing: The forged slab is machined to achieve a surface roughness of 30-60 μm. Then, ultrasonic testing is performed to ensure that there are no metallurgical defects such as delamination or folding inside the slab.

[0065] 5) Controlled Rolling: The machined alloy slab is heated and subjected to multiple hot rolling processes; after surface grinding, it undergoes multiple cold rolling processes to a thickness of 4-6 mm. Specifically, the first hot rolling process has an initial rolling temperature of 1200 ℃, 8 rolling passes, a total deformation of 50%, and a final rolling temperature control range of 1050 ℃, followed by material separation; the second hot rolling process has an initial rolling temperature of 1180 ℃, 5 rolling passes, a total deformation of 45%, and a final rolling temperature control range of 1050 ℃, followed by material separation; the third hot rolling process has an initial rolling temperature of 1200 ℃, 5 rolling passes, a total deformation of 55%, and a final rolling temperature control range of 1080 ℃, followed by material separation. The cold rolling processes following the third hot rolling process do not exceed 5 passes, and the total deformation is not less than 45%.

[0066] 6) Solution treatment: The alloy sheet after microstructure control rolling is solution treated in a high-temperature precision heat treatment furnace at a temperature of 1200 ℃ and a holding time of 60 minutes. After heat treatment, it is cooled to room temperature by water to obtain nickel-based deformable high-temperature alloy sheet resistant to molten salt corrosion.

[0067] Example 3

[0068] A method for controlling the microstructure of nickel-based deformable superalloy plates resistant to molten salt corrosion includes the following steps:

[0069] 1) Ingot Preparation: The alloy raw materials are added to a high-frequency vacuum induction furnace at a melting temperature of 1500 ℃ and a vacuum degree of 0.5×10-2 Pa. After the raw materials are completely melted, they are refined at 1550 ℃ for 15 minutes. Then, inert gas is introduced and the alloy liquid is poured into ingots, with the pouring temperature controlled within the range of 1450±20 ℃. After the vacuum-melted ingot cools, the ingot, after the riser is removed and polished, is placed in an electroslag remelting equipment as an electrode. After three steps of remelting operations—arc initiation, flux melting, and capping and feeding—the refined alloy ingot obtained by electroslag remelting is obtained. Specifically, the alloy components by weight percentage are: C 0.05%, Cr 6.0%, W 25.0%, Fe 0.5%, Mn 0.5%, Si 0.1%, Mo 0.5%, Ti 0.2%, with the balance being Ni.

[0070] 2) Homogenization treatment: The alloy ingot is subjected to the first homogenization treatment at 1230 ℃ for 5 hours in a resistance furnace, followed by the second homogenization treatment at 1270 ℃ for 15 hours.

[0071] 3) Forging slab: The homogenized master alloy ingot is forged into a slab with a thickness of 50 mm, wherein the forging heating temperature is 1180 ℃ and the final forging temperature is 930 ℃.

[0072] 4) Machining and ultrasonic testing: The forged slab is machined to achieve a surface roughness of 30-60 μm. Then, ultrasonic testing is performed to ensure that there are no metallurgical defects such as delamination or folding inside the slab.

[0073] 5) Controlled Rolling: The machined alloy slab is heated and subjected to multiple hot rolling processes; after surface grinding, it undergoes multiple cold rolling processes to a thickness of 4-6 mm. Specifically, the first hot rolling process has an initial rolling temperature of 1180 ℃, 5 rolling passes, a total deformation of 40%, and a final rolling temperature control range of 1050 ℃, followed by material separation; the second hot rolling process has an initial rolling temperature of 1150 ℃, 4 rolling passes, a total deformation of 35%, and a final rolling temperature control range of 1030 ℃, followed by material separation; the third hot rolling process has an initial rolling temperature of 1200 ℃, 5 rolling passes, a total deformation of 45%, and a final rolling temperature control range of 1080 ℃, followed by material separation. The cold rolling processes following the third hot rolling process do not exceed 5 passes, and the total deformation is not less than 45%.

[0074] 6) Solution treatment: The alloy sheet after microstructure control rolling is solution treated in a high-temperature precision heat treatment furnace at a temperature of 1200 ℃ and a holding time of 60 minutes. After heat treatment, it is cooled to room temperature by water to obtain nickel-based deformable high-temperature alloy sheet resistant to molten salt corrosion.

[0075] Example 4

[0076] A method for controlling the microstructure of nickel-based deformable superalloy plates resistant to molten salt corrosion includes the following steps:

[0077] 1) Ingot Preparation: The alloy raw materials are added to a high-frequency vacuum induction furnace at a melting temperature of 1500 ℃ and a vacuum degree of 0.5×10-2 Pa. After the raw materials are completely melted, they are refined at 1550 ℃ for 15 minutes. Then, inert gas is introduced and the alloy liquid is poured into ingots, with the pouring temperature controlled within the range of 1450±20 ℃. After the vacuum-melted ingot cools, the ingot, after the riser is removed and polished, is placed in an electroslag remelting equipment as an electrode. After three steps of remelting—arc initiation, flux melting, and capping and feeding—the refined alloy ingot obtained by electroslag remelting is obtained. Specifically, the alloy components by weight percentage are: C 0.05%, Cr 6.0%, W 25.0%, Fe 0.5%, Mn 0.5%, Si 0.1%, Mo 0.5%, Ti 0.2%, Zr 0.1%, with the balance being Ni.

[0078] 2) Homogenization treatment: The alloy ingot is subjected to the first homogenization treatment at 1230 ℃ for 5 hours in a resistance furnace, followed by the second homogenization treatment at 1270 ℃ for 15 hours.

[0079] 3) Forging slab: The homogenized master alloy ingot is forged into a slab with a thickness of 50 mm, wherein the forging heating temperature is 1180 ℃ and the final forging temperature is 930 ℃.

[0080] 4) Machining and ultrasonic testing: The forged slab is machined to achieve a surface roughness of 30-60 μm. Then, ultrasonic testing is performed to ensure that there are no metallurgical defects such as delamination or folding inside the slab.

[0081] 5) Controlled Rolling: The machined alloy slab is heated and subjected to multiple hot rolling processes; after surface grinding, it undergoes multiple cold rolling processes to a thickness of 4-6 mm. Specifically, the first hot rolling process has an initial rolling temperature of 1100 ℃, 5 rolling passes, a total deformation of 40%, and a final rolling temperature control range of 950 ℃, followed by material separation; the second hot rolling process has an initial rolling temperature of 1100 ℃, 4 rolling passes, a total deformation of 35%, and a final rolling temperature control range of 970 ℃, followed by material separation; the third hot rolling process has an initial rolling temperature of 1150 ℃, 5 rolling passes, a total deformation of 45%, and a final rolling temperature control range of 1000 ℃, followed by material separation. The cold rolling processes following the third hot rolling process do not exceed 5 passes, and the total deformation is not less than 45%.

[0082] 6) Solution treatment: The alloy sheet after microstructure control rolling is solution treated in a high-temperature precision heat treatment furnace at a temperature of 1200 ℃ and a holding time of 60 minutes. After heat treatment, it is cooled to room temperature by water to obtain nickel-based deformable high-temperature alloy sheet resistant to molten salt corrosion.

[0083] Example 5

[0084] A method for controlling the microstructure of nickel-based deformable superalloy plates resistant to molten salt corrosion includes the following steps:

[0085] 1) Ingot Preparation: The alloy raw materials are added to a high-frequency vacuum induction furnace at a melting temperature of 1500 ℃ and a vacuum degree of 0.5×10-2 Pa. After the raw materials are completely melted, they are refined at 1550 ℃ for 15 minutes. Then, inert gas is introduced and the alloy liquid is poured into ingots, with the pouring temperature controlled within the range of 1450±20 ℃. After the vacuum-melted ingot cools, the ingot, after the riser is removed and polished, is placed in an electroslag remelting equipment as an electrode. After three steps of remelting—arc initiation, flux melting, and capping and feeding—the refined alloy ingot obtained by electroslag remelting is obtained. Specifically, the alloy components by weight percentage are: C 0.05%, Cr 6.0%, W 25.0%, Fe 0.5%, Mn 0.5%, Si 0.1%, Mo 0.5%, Ti 0.2%, Zr 0.1%, with the balance being Ni.

[0086] 2) Homogenization treatment: The alloy ingot is subjected to the first homogenization treatment at 1230 ℃ for 5 hours in a resistance furnace, followed by the second homogenization treatment at 1270 ℃ for 15 hours.

[0087] 3) Forging slab: The homogenized master alloy ingot is forged into a slab with a thickness of 60 mm, wherein the forging heating temperature is 1180 ℃ and the final forging temperature is 930 ℃.

[0088] 4) Machining and ultrasonic testing: The forged slab is machined to achieve a surface roughness of 30-60 μm. Then, ultrasonic testing is performed to ensure that there are no metallurgical defects such as delamination or folding inside the slab.

[0089] 5) Controlled Rolling: The machined alloy slab is heated and subjected to multiple hot rolling passes; after surface grinding, it is cold rolled multiple times to a thickness of 4-6 mm. Specifically, the first hot rolling process has an initial rolling temperature of 1150 ℃, 5 rolling passes, a total deformation of 40%, and a final rolling temperature control range of 1000 ℃, followed by material separation; the second hot rolling process has an initial rolling temperature of 1150 ℃, 5 rolling passes, a total deformation of 40%, and a final rolling temperature control range of 1000 ℃, followed by material separation; the third hot rolling process has an initial rolling temperature of 1180 ℃, 5 rolling passes, a total deformation of 50%, and a final rolling temperature control range of 1050 ℃, followed by material separation. The cold rolling passes after the third hot rolling process do not exceed 5, and the total deformation is not less than 45%.

[0090] 6) Solution treatment: The alloy sheet after microstructure control rolling is solution treated in a high-temperature precision heat treatment furnace at a temperature of 1200 ℃ and a holding time of 60 minutes. After heat treatment, it is cooled to room temperature by water to obtain nickel-based deformable high-temperature alloy sheet resistant to molten salt corrosion.

[0091] The microstructure diagram of the high-temperature alloy sheet prepared in Example 5 is shown below. Figure 3 As shown.

[0092] The nickel-based deformable superalloy plates resistant to molten salt corrosion prepared in the above embodiments of this application all exhibited a uniform fine-grained microstructure. The hot rolling and cold rolling processes effectively controlled the grain size, with the average grain size of all plates being less than 50 μm and exhibiting excellent microstructure uniformity, with grain size differences of less than 2 levels. In Examples 4 and 5, trace element Zr was added to the alloy composition. The process implemented in this application can be applied to alloys with both compositions. Zr can further refine the microstructure, control the grain size during rolling, improve grain boundary strength, and widen the rolling processing range.

[0093] In summary, the microstructure-controlled rolling method for nickel-based deformable superalloy plates resistant to molten salt corrosion provided in this application can successfully prepare fine-grained high-tungsten superalloy plates. The preparation process provided in this application combines a full-process approach including high-temperature alloy purification smelting, step-by-step high-temperature annealing, microstructure-controlled rolling of plates with large deformation, and surface process control of the plates. This enables microstructure control under conditions of large deformation cold rolling. Simultaneously, multi-stage microstructure-controlled hot rolling effectively optimizes the microstructure and refines the grains, resulting in fine-grained plates with high purity and uniform microstructure, providing a technological guarantee for the application of corrosion-resistant materials in high-performance molten salt reactors.

[0094] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, if it refers to performing an action according to a certain element, it means performing the action at least according to that element, including two cases: performing the action only according to that element, and performing the action according to that element and other elements. Expressions such as "multiple," "repeatedly," and "various" include two, two times, two kinds, and more than two, more than two times, and more than two kinds.

[0095] This specification includes combinations of various embodiments described herein. Individual references to embodiments (e.g., “one embodiment”, “some embodiments”, or “preferred embodiments”) do not necessarily refer to the same embodiment; however, these embodiments are not mutually exclusive unless indicated to be mutually exclusive or are readily apparent to those skilled in the art. It should be noted that the word “or” is used in a non-exclusive sense throughout this specification unless the context explicitly indicates or requires it.

[0096] All references to this application are considered to be incorporated in their entirety into the disclosure of this application so that they can serve as a basis for modifications if necessary. Furthermore, it should be understood that after reading the contents of this application, those skilled in the art can make various alterations or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A method for controlling the microstructure of nickel-based deformable high-temperature alloy plates resistant to molten salt corrosion, characterized in that, Includes the following steps: Step 1) Prepare raw materials according to the standard proportions of each element in the alloy, and use a double melting process. Stir during smelting to obtain a cast ingot with uniform composition. Step 2) The ingot is subjected to step-by-step homogenization annealing at a temperature not lower than 1200℃; Step 3) Forge the annealed ingot into a 50-60mm slab, wherein the forging heating temperature is 1180±20℃ and the final forging temperature is not lower than 900℃; Step 4) Machining the forged slab to achieve a surface roughness of 30-60 μm. Step 5) The machined slab is subjected to multiple hot rolling processes, including: First hot rolling: heating to 950-1200℃, rolling 5-10 times, with a total deformation of 40%-50%, then separating the material; Second hot rolling: heating to 950-1200℃, rolling 4-6 times, with a total deformation of 35%-50%, then separating the material; Third hot rolling: heating to 950-1200℃, rolling 4-6 times, with a total deformation of 45%-60%; After hot rolling to 10-20mm, the surface is ground, and then cold rolled to 4-6mm, with no more than 5 cold rolling passes and a total deformation of not less than 45%; Step 6) The rolled alloy sheet is solution treated in a heat treatment furnace at a temperature of 1200±10℃ and a holding time of 30-90 minutes. After heat treatment, it is cooled by water quenching. In step 1), The alloy is formulated in the following standard weight percentages: Cr: 6.0-8.0%, W: 24.0-28.0%, Fe: 0.5-0.55%, Mn: 0.5-0.8%, Si: 0.1-0.4%, C: 0.025-0.08%, Mo: 0-1.0%, Ti: 0-0.2%, Ni: balance. The alloy does not contain Zr; or... The alloy is formulated in the following standard weight percentages: Cr: 6.0-8.0%, W: 24.0-28.0%, Fe: 0.5-0.55%, Mn: 0.5-0.8%, Si: 0.1-0.4%, C: 0.025-0.08%, Mo: 0-1.0%, Ti: 0-0.2%, Zr: 0-0.1%, Ni: balance; wherein, the Zr composition does not include a zero point. The addition of Zr refines the alloy grains and improves the grain boundary strength, which is beneficial for microstructure control and large deformation rolling.

2. The method for controlling the microstructure of nickel-based deformable high-temperature alloy plates resistant to molten salt corrosion according to claim 1, characterized in that, The dual-stage melting process includes vacuum induction melting and vacuum consumable melting, and electromagnetic stirring is used during the melting process. The temperature control range of the alloy liquid in the vacuum induction melting stage is 1550±20℃, the melting time is 15-20 minutes, and the casting temperature control range after melting is 1450±20℃.

3. The method for controlling the microstructure of nickel-based deformable high-temperature alloy plates resistant to molten salt corrosion according to claim 1 or 2, characterized in that, In the solution treatment, the heating rate of the plate is 0.5-1.0 mm / min.

4. The method for controlling the microstructure of nickel-based deformable high-temperature alloy plates resistant to molten salt corrosion according to claim 1 or 2, characterized in that, Following step 4), the following steps are also included: Ultrasonic testing is performed on the slabs obtained from machining.

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