Manufacturing method of precipitation hardening type nickel-based wrought superalloy GH141 cold-rolled sheet

Abstract

The invention belongs to the field of metal material manufacturing, and particularly relates to a manufacturing method of a precipitation hardening type nickel-based high-temperature alloy GH141 cold-rolled sheet, which solves the problems of poor thermoplasticity, easy cracking, difficult cooling control and the like in the GH141 cold-rolled sheet processing by optimizing the technological process, and comprises the following steps: carrying out high-temperature homogenization treatment on a steel ingot; the homogenization temperature and the cooling mode are optimized to improve thermoplasticity; during forging cogging, preheating, sheathing and fast forging processes are adopted, so that heat loss is reduced, and the forging temperature interval is guaranteed; the heating temperature, the finish rolling temperature and the pass deformation are strictly controlled in the hot rolling process, and the plate quality is ensured; in the cold rolling stage, a semi-finished product is rolled at a large reduction rate, and the shape and performance of a finished product are controlled through a multi-pass small-deformation process; the cooling speed is particularly optimized in the solution treatment of the finished product, and rapid water cooling is realized. According to the method, the mechanical property and the surface quality of the GH141 alloy cold-rolled sheet are effectively improved, the use requirement in a high-temperature environment is met, and the method has remarkable industrial application value.

Description

Technical Field

[0001] The invention relates to the technical field of alloy preparation, and in particular to a method for manufacturing a precipitation hardening nickel-based deformable high-temperature alloy GH141 cold-rolled thin plate. Background Art

[0002] Precipitation-hardening nickel-based superalloys have important application value in key parts in aerospace and other fields due to their excellent high-temperature performance and mechanical properties. GH141 (new grade GH4141) is a high-performance precipitation-hardening deformation superalloy developed by imitating the American Rene'41 nickel-based superalloy and optimizing the composition. It strengthens the grain boundaries by adding trace elements B, Mg and Zr, so that the alloy has good strength and toughness under high temperature conditions. Especially in jet engine components, extremely high requirements are placed on the thermal strength, thermal stability and process adaptability of the material. The research and development of GH141 alloy fills the technical gap of similar materials in China and realizes partial import substitution.

[0003] However, due to the high alloying characteristics of GH141 alloy, its hot working plasticity is poor, the forging temperature range is narrow, and the processing is difficult. These characteristics make the manufacturing process of cold-rolled thin plates face many challenges:

[0004] Difficulties in homogenizing steel ingots: During high-temperature homogenization, large-sized γ' phase particles are precipitated at the grain boundaries, which improves the thermoplasticity of the alloy. However, different cooling methods have a significant impact on the effect of homogenization. Improper cooling conditions will lead to a decrease in hot working performance and increase the risk of cracking during ingot opening.

[0005] Difficulty in forging: GH141 alloy has high deformation resistance and is a typical difficult-to-deform alloy. Its hot working temperature window is narrow, only 60-80°C. During the forging process, due to rapid heat loss, cracks are very likely to occur if the final forging temperature is not well controlled. Therefore, how to optimize the heating and insulation process of the billet, reduce heat loss during processing, and ensure the forging temperature range is an urgent problem to be solved.

[0006] The hot rolling finishing process is complex: The hot rolling finishing rolling of GH141 alloy slabs has strict requirements on temperature control and deformation. The thinner the plate thickness, the faster the temperature drop, and frequent heating is required to ensure that the final rolling temperature is greater than 950℃. It is required that the number of rolling passes per fire should not exceed 3, and the deformation of a single pass should not be less than 8%. These factors put forward higher technical requirements on the pressure capacity and process control of the rolling mill equipment.

[0007] Limitations of cold rolling and subsequent processing: During the cold rolling process, GH141 alloy needs to adopt a large reduction rate and multiple small deformation processes. The total deformation rate of the semi-finished product is controlled at 30-35%, and the cooling rate of the finished plate plays a decisive role in its final performance. Foreign literature shows that the material can only meet the performance requirements if it is water-cooled within 5 seconds, which puts strict requirements on the solution heat treatment equipment and process control.

[0008] Challenges of surface treatment: The pickling process is sensitive to acid concentration and temperature control. Over-pickling will cause pinhole defects, while under-pickling will cause surface mottle and yellow film problems, affecting the quality of the finished product.

[0009] In summary, the existing technology has the following main defects when manufacturing precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled thin plates:

[0010] The homogenization effect of steel ingots is difficult to control, and cracks are prone to occur during the blanking process; the hot rolling temperature range is narrow, and the deformation pass and final rolling temperature are difficult to control; the cold rolling process is complex and the plate cooling speed is required to be high; the surface pickling process has poor stability and is prone to quality defects.

[0011] In view of the above problems, it is urgent to develop an optimized manufacturing method to improve the processing performance and product quality of GH141 alloy cold-rolled thin plate, while meeting the technical requirements of its mechanical properties and surface quality. Summary of the invention

[0012] The technical problem to be solved by the present invention is to provide a method for manufacturing precipitation hardened nickel-based high-temperature alloy GH141 cold-rolled thin plate, so as to solve the problems of cracking during forging and edge cracking during rolling as well as unsatisfactory performance of the finished cold-rolled thin plate in the conventional manufacturing method in the prior art.

[0013] In order to overcome the above defects of the prior art, the present invention provides a method for manufacturing a precipitation hardened nickel-based high-temperature alloy GH141 cold-rolled sheet, comprising the following steps:

[0014] S1: High temperature homogenization heat treatment of steel ingot:

[0015] Take GH141 alloy steel ingot and perform homogenization treatment to improve the thermoplasticity of the steel ingot;

[0016] S2: Forging and blanking:

[0017] The steel ingot is preheated, and then the preheated steel ingot is returned to the furnace to a temperature of 1200±20° C., and forged to obtain a billet;

[0018] S3: Hot rolling treatment:

[0019] The blank obtained after forging in step S2 is subjected to hot rolling and hot finishing rolling in sequence to obtain a semi-finished plate; the hot rolling temperature is 1210±20°C, and the hot finishing rolling final rolling temperature is greater than 950°C;

[0020] S4: Heat treatment of semi-finished products:

[0021] Performing solution heat treatment on the semi-finished plate obtained in step S3;

[0022] S5: Pickling:

[0023] The semi-finished plate treated in step S4 is pickled;

[0024] S6: Cold rolling:

[0025] Cold rolling the semi-finished plate obtained in step S5;

[0026] Semi-finished products are cold rolled with large deformation, the deformation rate of the first three passes reaches more than 12%, and the total deformation is controlled at 30-35%; finished products are cold rolled with multiple passes of small deformation technology to ensure the plate shape and mechanical properties;

[0027] S7: Finished product heat treatment:

[0028] The finished plates are subjected to solution heat treatment, and the heating temperature, time and water exposure time are controlled. The water exposure time does not exceed 5 seconds, and they are cooled quickly to ensure material performance.

[0029] Compared with the prior art, the manufacturing method of the precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled thin plate of the present invention has the following advantages: the manufacturing method of the present invention comprehensively optimizes the manufacturing process of the GH141 alloy cold-rolled thin plate by improving key steps such as homogenization heat treatment, forging blanking, hot rolling treatment, pickling, cold rolling, and finished product heat treatment; by adopting high-temperature homogenization heat treatment in the homogenization heat treatment, the thermoplasticity of the steel ingot is improved, which provides a good foundation for subsequent processing; in the forging blanking process, the combined process of "preheating + insulation cotton coating + fast forging" is used to ensure the stability of the forging temperature, and avoid cracks caused by insufficient temperature in the blanking process; in the hot rolling process, the process design of "low-temperature preheating → coating protection → high-temperature heating → multiple rolling" is adopted, and the blank is heated to 12 10±20℃ to ensure good thermoplasticity, and the final rolling temperature is strictly controlled at above 950℃ in the hot rolling and finishing stage, ensuring the uniformity of the structure and dimensional stability of the semi-finished plate; in the cold rolling process, large deformation and small reduction multi-pass processes are adopted for the semi-finished and finished plates respectively, so as to optimize the accuracy and mechanical properties of the plate shape; in the heat treatment of the finished product, the grain growth is avoided by controlling the solid solution temperature, and the strength and toughness of the material are optimized at the same time; the overall preparation method design of the present invention focuses on the synergistic effect of each process, so that the precipitation of γ' phase and carbide is uniform and the size is reasonable, thereby strengthening the structure and performance of the alloy, solving the technical problems of large fluctuation of material performance and insufficient strength and toughness in the prior art, and finally making the finished GH141 cold-rolled thin plate have excellent mechanical properties, heat resistance and high temperature strength.

[0030] In a possible implementation, in step S1, the homogenization treatment is performed under the following conditions: treatment at a temperature of 1170±20° C. for 6-7 hours, followed by furnace cooling.

[0031] Compared with the prior art, the above technical solution can significantly improve the thermoplasticity of GH141 alloy steel ingot. The homogenization treatment promotes the initial precipitation and uniform distribution of the γ' phase through high temperature and long-term heat preservation, while reducing the internal stress and component segregation in the alloy. The uniformly distributed γ' phase can not only strengthen the matrix, but also reduce the deformation resistance of the steel ingot, so that it can show better processing performance in the subsequent forging and hot rolling process. The furnace cooling method can avoid the structural stress concentration and large structural gradient caused by rapid cooling, and effectively maintain the structural stability inside the steel ingot.

[0032] In a possible implementation, in step S2, the preheating condition is: preheating the steel ingot to 1200±20°C, and then coating the steel ingot with thermal insulation cotton.

[0033] Compared with the prior art, the above technical solution can effectively reduce the heat loss of the steel ingot during the process from preheating to blanking forging. By preheating the steel ingot to a temperature close to the upper limit of forging blanking (1200±20℃), the deformation resistance of the steel ingot can be significantly reduced, thereby improving the hot working plasticity of the difficult-to-deform nickel-based high-temperature alloy. After the surface of the steel ingot is coated with thermal insulation cotton, the temperature drop of the steel ingot between being discharged from the furnace and being returned to the furnace can be further slowed down, thereby avoiding surface cracking caused by large temperature gradient and local insufficient temperature during forging. Through the synergistic effect of reasonable preheating temperature and insulation measures, the processing problem caused by heat loss of high-alloy nickel-based steel ingots in the prior art is overcome, which not only meets the temperature requirements of the forging process, but also significantly improves the processing adaptability of the steel ingot and the overall product qualification rate.

[0034] In a possible embodiment, in step S3, the hot rolling conditions are: heating the billet to 1180±10°C, keeping it warm for 1.5 hours, then taking it out of the furnace and wrapping the billet with insulation material, then loading the billet into a heating furnace, heating it to 1210±20°C, keeping it warm for 40 minutes, and then rolling it.

[0035] Compared with the prior art, the above technical scheme can effectively reduce the problems of large deformation resistance and poor plasticity of the billet caused by insufficient temperature during hot rolling. The first step is to heat the billet to 1180±10℃ and keep it warm for 1.5 hours, which helps to improve the overall temperature uniformity of the billet and reduce the adverse effect of temperature difference during rolling on deformation performance. Subsequently, the billet after being taken out of the furnace is wrapped with insulation material to slow down its temperature drop rate, avoid excessive surface cooling and increased temperature difference due to exposure to the environment, thereby improving the surface plasticity during rolling. The billet is returned to the furnace and heated to 1210±20℃ and kept warm for 40 minutes to further ensure that the billet has sufficient hot processing plasticity when entering the rolling stage. By heating in stages, reasonable insulation and controlling the rolling temperature, not only the problems of insufficient plasticity and temperature loss in the hot rolling process of high-alloyed billets in the prior art are overcome, but also the efficiency of hot rolling and product qualification rate are improved, laying an important foundation for subsequent processing technology.

[0036] In a possible implementation, in step S3, the conditions for hot rolling and finishing are: rolling is performed by multiple heating, and the number of rolling passes for each heating is no more than 3, and the deformation of each pass is not less than 8%; the cooling method after rolling is single-piece separate cooling.

[0037] Compared with the prior art, the above technical scheme effectively solves the problems of uneven plate temperature, increased deformation resistance and final performance degradation caused by too fast temperature drop during hot rolling and finishing, and maintains the temperature stability of the plate during rolling by multiple heating to avoid the degradation of processing performance due to rapid cooling; the number of rolling passes for each heating is limited to no more than 3, and the deformation amount of each pass is strictly controlled to be no less than 8%, which helps to give full play to the plasticity of the material in the appropriate temperature range, make the deformation more uniform and sufficient, and reduce defects caused by insufficient local deformation or stress concentration; after rolling, a single-piece separate cooling method is adopted to prevent the influence of temperature difference when multiple pieces are cooled, and avoid internal stress unevenness and deformation defects caused by stacking cooling. By optimizing the number of heating times, rolling passes, deformation amount and cooling method, the problems of poor plasticity, difficult to control dimensional accuracy and subsequent unstable performance of high-temperature alloys in hot rolling and finishing in the prior art are overcome.

[0038] In a possible implementation, in step S4, the conditions of the solution heat treatment are: the solution temperature is 1080±10° C., and the solution time is less than 2 hours.

[0039] Compared with the prior art, the above technical scheme can significantly improve the microstructure uniformity and mechanical properties of GH141 alloy during heat treatment. By precisely controlling the solution temperature within the range of 1080±10°C, the γ' phase and part of the carbides (MC and M6C) in the alloy can be fully dissolved and redistributed in the matrix, thereby reducing grain boundary segregation and residual stress and optimizing the microstructure of the alloy. Controlling the solution time to less than 2 hours not only ensures that the strengthening phase in the alloy is fully dissolved, but also effectively avoids the problem of grain growth and toughness reduction due to too long treatment time.

[0040] In a possible implementation, in step S5, the pickling conditions are: pickling is performed using sulfuric acid with a concentration of 45-50%, and the temperature of the sulfuric acid is 80-90°C.

[0041] Compared with the prior art, the above technical solution can effectively solve the problems of uneven pickling effect, over-pickling or under-pickling in the traditional pickling process, ensure the purity and quality of the surface of the GH141 alloy cold-rolled sheet, and provide sufficient corrosion capacity to remove surface oxide scale and impurities by controlling the sulfuric acid concentration at 45-50%, but avoid excessive concentration causing over-pickling and producing pinhole defects; at the same time, controlling the acid temperature at 80-90°C can increase the reaction rate of pickling, ensure efficient and uniform surface cleaning within a limited time, and avoid the risk of accelerated acid volatilization or local corrosion due to excessively high temperature.

[0042] In a possible embodiment, in step S6, the cold rolling treatment includes semi-finished product cold rolling and finished product cold rolling, and the semi-finished product cold rolling includes: cold rolling the semi-finished product sheet by a large deformation method, and the deformation rate of the first three passes reaches more than 12%, and the total deformation rate of the rolling process is 30-35%; the finished product cold rolling is carried out after the semi-finished product cold rolling is completed, and the condition is: cold rolling the semi-finished product cold rolled sheet by a small reduction and multiple passes deformation method.

[0043] Compared with the existing technology, the above technical scheme can significantly optimize the mechanical properties and shape control of the plate during the cold rolling process, ensure that the cold-rolled thin plate achieves a balance between deformation and mechanical properties, and through the high-pass deformation rate design of semi-finished cold rolling (the deformation rate of the first three passes is ≥12%, and the total deformation is 30-35%), the refinement and densification effect of large deformation cold rolling on the alloy structure is fully utilized to improve the mechanical properties and uniformity of the plate; while the finished cold rolling further optimizes the flatness, surface quality and final dimensional accuracy of the plate through a deformation method of small reduction and multiple passes.

[0044] In a possible embodiment, in step S7, the temperature of the solution treatment is 1080±10°C, and after the solution treatment is completed and the plate is taken out of the furnace, it is water-cooled. The conditions of the water cooling treatment are: the plate is water-cooled after it is taken out of the furnace, and the water cooling treatment time is less than 5 seconds.

[0045] Compared with the prior art, the above technical scheme can significantly improve the comprehensive performance of the plate, especially its high-temperature strength, ductility and creep resistance. Through precise control of the solution treatment temperature (1080±10℃), the γ' strengthening phase in the GH141 alloy can be fully dissolved, and the carbides (such as MC, M6C) can be partially dissolved, reducing the coarse precipitation phase, thereby improving the microstructure uniformity of the alloy; in addition, after the solution treatment, rapid water cooling (water exposure time is less than 5 seconds) can effectively inhibit grain growth, retain the high-strength fine-grained structure formed in the solution process, and quickly fix the solute atoms to avoid grain boundary weakening and secondary phase precipitation.

[0046] In a possible implementation manner, after step S7 is completed, step S8 of flattening the finished product is further included, including: flattening the finished plate twice, and the total deformation rate of the two flattening treatments is ≤1%.

[0047] Compared with the existing technology, the above technical solution can effectively control the flatness and surface quality of the finished plate, while avoiding the degradation of mechanical properties caused by excessive deformation. Through two flattening treatments, the residual stress generated by the plate during heat treatment and cold rolling is gradually eliminated with a small deformation amount, thereby improving the flatness and dimensional stability of the plate. The total deformation rate is strictly limited to ≤1%, which can ensure that the microstructure of the material is not damaged, thereby retaining the strength and toughness of the plate. DETAILED DESCRIPTION

[0048] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0049] The process route of GH141 cold-rolled thin plate involved in the present invention is: selected raw materials → vacuum induction melting → electroslag remelting → vacuum consumable remelting → high-temperature homogenization treatment of steel ingots → forging and blanking → hot rolling → annealing → pickling → cold-rolled finished product, wherein the selected raw materials → vacuum induction melting → electroslag remelting → vacuum consumable remelting will not be repeated, and S1-S6 in the afternoon of this application correspond to the above-mentioned high-temperature homogenization treatment of steel ingots → forging and blanking → hot rolling → annealing → pickling → cold-rolled finished product, including:

[0050] The present invention provides a method for manufacturing a precipitation hardened nickel-based high-temperature alloy GH141 cold-rolled sheet, comprising the following steps:

[0051] S1: High temperature homogenization heat treatment of steel ingot:

[0052] Take GH141 alloy steel ingot and perform homogenization treatment to improve the thermoplasticity of the steel ingot;

[0053] S2: Forging and blanking:

[0054] The steel ingot is preheated, and then the preheated steel ingot is returned to the furnace to a temperature of 1200±20° C., and forged to obtain a billet;

[0055] S3: Hot rolling treatment:

[0056] The blank obtained after forging in step S2 is subjected to hot rolling and hot finishing rolling in sequence to obtain a semi-finished plate; the hot rolling temperature is 1210±20°C, and the hot finishing rolling final rolling temperature is greater than 950°C;

[0057] S4: Heat treatment of semi-finished products:

[0058] Performing solution heat treatment on the semi-finished plate obtained in step S3;

[0059] S5: Pickling:

[0060] The semi-finished plate treated in step S4 is pickled;

[0061] S6: Cold rolling:

[0062] Cold rolling the semi-finished plate obtained in step S5;

[0063] Semi-finished products are cold rolled with large deformation, the deformation rate of the first three passes reaches more than 12%, and the total deformation is controlled at 30-35%; finished products are cold rolled with multiple passes of small deformation technology to ensure the plate shape and mechanical properties;

[0064] S7: Finished product heat treatment:

[0065] The finished plate is subjected to solution heat treatment, and the heating temperature, time and water exposure time are controlled. The water exposure time does not exceed 5 seconds, and it is cooled quickly to ensure the material performance;

[0066] As a preferred solution, in step S1, the homogenization treatment is carried out under the following conditions: treatment at a temperature of 1170±20° C. for 6-7 hours, followed by furnace cooling.

[0067] Due to the particularity of GH141 alloy steel ingot, large-sized, square γ' particles are precipitated during the slow cooling process after heat preservation, thereby reducing the alloy's deformation resistance and improving its thermoplasticity. In order to reduce the cracking edge during the opening process of the billet, homogenization treatment must be carried out before forging. Its cooling method significantly affects the effect of homogenization heat treatment. After the steel ingot treated by the 1170±20℃x6-7h homogenization process is cooled with the furnace, the thermoplasticity is significantly improved.

[0068] As a preferred solution, in step S2, the preheating condition is: preheating the steel ingot to 1200±20°C, and then coating the steel ingot with thermal insulation cotton.

[0069] Since the alloying degree of GH141 alloy is high, the deformation resistance is large, and it is a difficult-to-deform alloy, the alloy has poor hot processing plasticity and is difficult to forge. The actual forging temperature range of the steel ingot in the factory is only 60-80℃. During forging, due to delays in the operation process, the heat loss is large, resulting in a lower forging temperature of the alloy, a narrower optimal hot processing temperature range, and poor control of the final forging temperature, it is easy to produce cracks. In order to reduce heat loss during processing and ensure the forging temperature range, the approach of this plan is: the billet is now preheated to 1200℃ in the heating furnace, wrapped with a layer of insulation cotton after being taken out of the furnace, and then returned to the furnace to heat to the billet opening temperature, and kept warm for 2 hours. At this time, the temperature is easy to use the upper limit temperature, which improves the forging effect.

[0070] As a preferred scheme, in step S3, the conditions for hot rolling are: heating the billet to 1180±10°C, keeping it warm for 1.5 hours, then taking it out of the furnace and wrapping the billet with insulation material, then loading the billet into a heating furnace, heating it to 1210±20°C, keeping it warm for 40 minutes, and then rolling it.

[0071] The above-mentioned hot rolling is carried out on a thin plate rolling mill. With reference to the characteristic that the hot processing plasticity is poor during forging, when rolling the thin plate, the temperature is increased by 10°C on the basis of the original forging temperature. The billet is heated to 1180±10°C in a step-type natural gas heating furnace, kept warm for 1.5 hours, quickly taken out of the furnace, and wrapped and bundled with pre-prepared insulation materials. Then it is craned to the furnace inlet of the heating furnace, quickly put into the furnace, and then the heating temperature is increased to 1210°C and kept warm for 40 minutes; as a preferred scheme, in the step S3, the conditions for hot rolling and finishing are: rolling is carried out by multiple heating, and the number of rolling passes for each heating fire does not exceed 3 times, and the deformation of each pass is not less than 8%; the cooling method after rolling is single-piece separate cooling.

[0072] Hot rolling and finishing rolling mainly provide raw materials for cold rolling of thin plates. Its temperature control, control of deformation of each pass and cooling speed after rolling are crucial to the rolling of cold-rolled plates. The thinner the plate, the faster the temperature drop. In order to ensure that the final rolling temperature is greater than 950℃, frequent heating can only be adopted. The number of rolling passes for each fire cannot exceed 3 passes, and the deformation of each pass cannot be less than 8%. This puts strict requirements on the rolling mill of a single plate. Under normal circumstances, the rolling pressure of the rolling mill shall not be less than 35000KN. In addition, the semi-finished products (equivalent to the cold-rolled billets) that have been finished rolled to size are not easy to cool. The best cooling method is to cool the single pieces separately after rolling is completed.

[0073] As a preferred solution, in step S4, the conditions of the solution heat treatment are: the solution temperature is 1080±10°C, and the solution time is less than 2 hours.

[0074] The solution heat treatment in the present invention has a great influence on the 760℃ tensile and 900℃ / 170MPa rupture properties of GH141 alloy. As the solution temperature increases, the strength and toughness and plasticity of the alloy decrease; as the solution time increases, the strength decreases slightly, but the toughness and plasticity decrease significantly. When aging at 760℃, the 760℃ tensile strength and toughness of the alloy increase synchronously with the extension of time; when aging above 800℃, as the aging temperature increases and the time increases, the 760℃ strength of the alloy decreases, and the toughness and plasticity increase.

[0075] As the solution temperature increases, the durability life generally shows a downward trend. Except for the 1080℃ solution treatment, the durability life increases with time. The durability life of the 1110℃ and 1120℃ solution treatments both decrease significantly after reaching a peak at 2h. The durability life of the 1120℃ treatment has decreased significantly. As the aging temperature increases, the durability life peaks at 800℃. The influence of aging time is small. Except for the 760℃ aging, the durability life decreases slightly with time. The durability life of the aging above 800℃ increases with time. Therefore, the best solution effect can be obtained by selecting 1080±10℃ and a solution time of less than 2 hours.

[0076] As a preferred solution, in step S5, the pickling conditions are: pickling is performed using sulfuric acid with a concentration of 45-50%, and the temperature of the sulfuric acid is 80-90°C.

[0077] The pickling in the present invention generally adopts H2SO4 pickling, the acid concentration is controlled at 45-50%, and the acid solution temperature is controlled at 80-90°C. Exceeding this concentration and temperature is very easy to over-pickling, resulting in pinhole defects. When the concentration is lower than 40% and the temperature is lower than 80°C, the surface of the plate has obvious under-pickling phenomenon, and the surface spots and yellow film are heavier.

[0078] As a preferred solution, in step S6, the cold rolling treatment includes semi-finished product cold rolling and finished product cold rolling, and the semi-finished product cold rolling includes: cold rolling the semi-finished product sheet by a large deformation method, and the deformation rate of the first three passes reaches more than 12%, and the total deformation rate of the rolling process is 30-35%; the finished product cold rolling is carried out after the semi-finished product cold rolling is completed, and the condition is: cold rolling the semi-finished product cold rolled sheet by a small reduction and multiple passes deformation method.

[0079] In the above cold rolling process, the semi-finished product cold rolling adopts a large deformation method, and the deformation rate of the first three passes reaches more than 12%. The total deformation rate of the rolling process is controlled at 30-35%, while the finished product rolling adopts a small pressure and multiple passes deformation method to ensure the control of the plate shape and the performance requirements of the finished product.

[0080] As a preferred solution, in step S7, the temperature of the solution treatment is 1080±10°C, and after the solution treatment is completed and the plate is taken out of the furnace, it is water-cooled. The conditions of the water-cooling treatment are: the plate is water-cooled after it is taken out of the furnace, and the water-cooling treatment time is less than 5 seconds.

[0081] In the manufacturing method of the present invention, the key to the heat treatment of the finished plate is to control the cooling rate. According to the research on GH141 alloy of the present invention, the steel can only meet the performance requirements if it is cooled by water within 5 seconds. Based on this feature, we specially improved the structure of the solid solution heat treatment furnace and added a fast furnace roller (30m / s) in the furnace discharge section. In addition to the γ matrix, the microstructure of GH141 alloy in the standard heat treatment state also has a γ' phase, MC, M6C, M 23 C6 type carbide. Among them, the γ phase is the main strengthening phase of the alloy, accounting for about 23.9% of the alloy. After aging at different temperatures and times, μ phase and σ phase will also precipitate. After heat treatment of the alloy, the phase transformation temperature range of the precipitated phase in the organization is shown in Table 1:

[0082] Table 1: Phase transformation temperature range of each precipitate phase in GH141 alloy

[0083]

[0084] During the solution treatment, the γ' phase dissolves, the carbide phase also dissolves or precipitates, and the grains grow. The grain size changes slightly after solution treatment at 1080℃; the grains grow significantly after solution treatment at temperatures above 1100℃, and the carbides (MC+M6C) begin to dissolve above 1100℃, and the amount decreases rapidly. 23 The amount of C6 increases. The dissolution of the dispersed γ' phase and the partial dissolution of the grain boundary carbides reduce their pinning effect on the grain boundary, resulting in rapid grain growth. Therefore, the temperature of the solution treatment is selected to be 1080±10℃, and the water cooling treatment time is less than 5 seconds.

[0085] As a preferred solution, after step S7, step S8 of flattening the finished product is further included, including: flattening the finished plate twice, and the total deformation rate of the two flattening treatments is ≤1%.

[0086] The following provides a specific embodiment combined with data in combination with the above-mentioned technical solution to further expand the technical solution of the present invention:

[0087] Embodiment 1:

[0088] This embodiment provides a method for manufacturing a precipitation hardened nickel-based deformed high-temperature alloy GH141 cold-rolled sheet, comprising the following steps:

[0089] S1: High temperature homogenization heat treatment of steel ingot: Put the GH141 alloy steel ingot into a heating furnace and keep it at 1170℃ for 6.5 hours for homogenization heat treatment to improve the thermoplasticity of the steel ingot, and then cool it with the furnace;

[0090] S2: Forging and blanking: The steel ingot after homogenization heat treatment is preheated to 1200°C, wrapped with insulation cotton after being taken out of the furnace, and then returned to the blanking temperature for 2 hours, and then forged and blanked to obtain a blank;

[0091] S3: Hot rolling treatment: The forged billet is subjected to hot rolling and hot finishing rolling in sequence:

[0092] (1) Hot rolling: The billet is heated to 1180°C, kept at this temperature for 1.5 hours, and then quickly taken out of the furnace and wrapped with insulation material. It is then heated to 1210°C again, kept at this temperature for 40 minutes, and then rolled.

[0093] (2) Hot rolling and finishing rolling: The billet after hot rolling is subjected to multiple heating and rolling, with each hot rolling pass not exceeding 3 passes and the deformation of each pass not less than 8%, so as to ensure that the final rolling temperature is greater than 950°C; after rolling, the billet is cooled by cooling the individual pieces separately to obtain a semi-finished plate;

[0094] S4: Semi-finished product heat treatment: The semi-finished product plate is subjected to solution heat treatment, and the specific conditions are: the solution temperature is 1080°C, and the solution time is not more than 2 hours, so as to improve the microstructure and properties of the plate;

[0095] S5: Pickling: The semi-finished plate after solution heat treatment is pickled with H2SO4 solution with an acid concentration of 47.5%, and the pickling temperature is controlled at 80-90℃ to remove surface oxides and impurities;

[0096] S6: Cold rolling treatment:

[0097] The pickled semi-finished plate is cold rolled, comprising the following steps:

[0098] (1) Cold rolling of semi-finished products: cold rolling is carried out by large deformation rolling method, the deformation rate of the first three passes is not less than 12%, and the total rolling deformation rate is controlled at 32.5%;

[0099] (2) Finished product cold rolling: After the semi-finished product is cold rolled, the plate is finished by a multi-pass small reduction deformation method to ensure the plate shape accuracy and final mechanical properties requirements;

[0100] S7: Finished product heat treatment: The finished cold-rolled plate is subjected to solution heat treatment. The specific conditions are: the solution treatment temperature is 1080°C, the solution treatment time is no more than 2 hours, and then the plate is water-cooled within 5 seconds after it comes out of the furnace, and the cooling rate is greater than 20°C / second to ensure that the plate performance meets the standard requirements;

[0101] S8: Finished product flattening: The finished plate is flattened twice, and the total deformation rate does not exceed 1% to ensure the flatness and dimensional accuracy of the plate. The thickness of the finished plate is 0.6mm.

[0102] Embodiment 2:

[0103] This embodiment provides a method for manufacturing a precipitation hardened nickel-based deformed high-temperature alloy GH141 cold-rolled sheet, comprising the following steps:

[0104] S1: High temperature homogenization heat treatment of steel ingot: Put the GH141 alloy steel ingot into a heating furnace and keep it at 1150℃ for 6 hours for homogenization heat treatment to improve the thermoplasticity of the steel ingot, and then cool it with the furnace;

[0105] S2: Forging and blanking: preheat the steel ingot after homogenization heat treatment to 1080°C, cover it with insulation cotton after it comes out of the furnace, return it to the blanking temperature, keep it warm for 2 hours, and then forge and blank to obtain the blank;

[0106] S3: Hot rolling treatment:

[0107] The forged billet is subjected to hot rolling and hot finishing rolling in sequence:

[0108] (1) Hot rolling: The billet is heated to 1170°C, kept at this temperature for 1.5 hours, and then quickly taken out of the furnace and wrapped with insulation material. It is then heated to 1190°C again, kept at this temperature for 40 minutes, and then rolled.

[0109] (2) Hot rolling and finishing rolling: The billet after hot rolling is subjected to multiple heating and rolling, with each hot rolling pass not exceeding 3 passes and the deformation of each pass not less than 8%, so as to ensure that the final rolling temperature is greater than 950°C; after rolling, the billet is cooled by cooling the individual pieces separately to obtain a semi-finished plate;

[0110] S4: Semi-finished product heat treatment: The semi-finished product plate is subjected to solution heat treatment, and the specific conditions are: the solution temperature is 1080±10°C, and the solution time is not more than 2 hours, so as to improve the microstructure and properties of the plate;

[0111] S5: Pickling: The semi-finished plate after solution heat treatment is pickled with a H2SO4 solution with an acid concentration of 45%, and the pickling temperature is controlled at 80-90°C to remove surface oxides and impurities;

[0112] S6: Cold rolling treatment:

[0113] The pickled semi-finished plate is cold rolled, comprising the following steps:

[0114] (1) Cold rolling of semi-finished products: cold rolling is carried out by large deformation rolling method, the deformation rate of the first three passes is not less than 12%, and the total rolling deformation rate is controlled at 30%;

[0115] (2) Finished product cold rolling: After the semi-finished product is cold rolled, the plate is finished by a multi-pass small reduction deformation method to ensure the plate shape accuracy and final mechanical properties requirements;

[0116] S7: Finished product heat treatment: The finished cold-rolled plate is subjected to solution heat treatment. The specific conditions are: the solution treatment temperature is 1070°C, the solution treatment time is no more than 2 hours, and then the plate is water-cooled within 5 seconds after it comes out of the furnace, and the cooling rate is greater than 20°C / second to ensure that the plate performance meets the standard requirements;

[0117] S8: Finished product flattening: The finished plate is flattened twice, and the total deformation rate does not exceed 1% to ensure the flatness and dimensional accuracy of the plate. The thickness of the finished plate is 0.6mm.

[0118] Embodiment 3:

[0119] This embodiment provides a method for manufacturing a precipitation hardened nickel-based deformed high-temperature alloy GH141 cold-rolled sheet, comprising the following steps:

[0120] S1: High temperature homogenization heat treatment of steel ingot: Put the GH141 alloy steel ingot into a heating furnace and keep it at 1190℃ for 6-7 hours for homogenization heat treatment to improve the thermoplasticity of the steel ingot, and then cool it with the furnace;

[0121] S2: Forging and blanking: preheat the steel ingot after homogenization heat treatment to 1220°C, cover it with insulation cotton after it comes out of the furnace, return it to the blanking temperature, keep it warm for 2 hours, and then forge and blank to obtain the blank;

[0122] S3: Hot rolling treatment:

[0123] The forged billet is subjected to hot rolling and hot finishing rolling in sequence:

[0124] (1) Hot rolling: The billet is heated to 1190°C, kept at this temperature for 1.5 hours, and then quickly taken out of the furnace and wrapped with insulation material. It is then heated to 1230°C again, kept at this temperature for 40 minutes, and then rolled.

[0125] (2) Hot rolling and finishing rolling: The billet after hot rolling is subjected to multiple heating and rolling, with each hot rolling pass not exceeding 3 passes and the deformation of each pass not less than 8%, so as to ensure that the final rolling temperature is greater than 950°C; after rolling, the billet is cooled by cooling the individual pieces separately to obtain a semi-finished plate;

[0126] S4: Semi-finished product heat treatment: The semi-finished product plate is subjected to solution heat treatment, and the specific conditions are: the solution temperature is 1090°C, and the solution time is not more than 2 hours, so as to improve the microstructure and properties of the plate;

[0127] S5: Pickling: The semi-finished plate after solution heat treatment is pickled with a H2SO4 solution with an acid concentration of 50%, and the pickling temperature is controlled at 80-90°C to remove surface oxides and impurities;

[0128] S6: Cold rolling treatment:

[0129] The pickled semi-finished plate is cold rolled, comprising the following steps:

[0130] (1) Cold rolling of semi-finished products: cold rolling is carried out by large deformation rolling method, the deformation rate of the first three passes is not less than 12%, and the total deformation rate of the rolling process is controlled at 35%;

[0131] (2) Finished product cold rolling: After the semi-finished product is cold rolled, the plate is finished by a multi-pass small reduction deformation method to ensure the plate shape accuracy and final mechanical properties requirements;

[0132] S7: Finished product heat treatment: The finished cold-rolled plate is subjected to solution heat treatment. The specific conditions are: the solution treatment temperature is 1090°C, the solution treatment time is no more than 2 hours, and then the plate is water-cooled within 5 seconds after it comes out of the furnace, and the cooling rate is greater than 20°C / second to ensure that the plate performance meets the standard requirements;

[0133] S8: Finished product flattening: The finished plate is flattened twice, and the total deformation rate does not exceed 1% to ensure the flatness and dimensional accuracy of the plate. The thickness of the finished plate is 0.6mm.

[0134] The mechanical properties of the GH141 cold-rolled sheets obtained in the above-mentioned embodiments 1-3 were tested by random sampling. The test results are shown in Table 2, where the cold rolling end state corresponds to the sheet after the cold rolling treatment in step S6, and the cold rolling end + solution treatment corresponds to the sheet after the finished product heat treatment in step S7:

[0135] Table 2 Mechanical properties of 0.6 mm GH141 cold-rolled sheet

[0136]

[0137] From Table 2, we can know that at the end of cold rolling, that is, without aging treatment, the tensile strength (σb) of GH141 alloy is between 980MPa and 1021MPa, the yield strength (σ0.2) is between 650MPa and 662MPa, the elongation (δ5) is between 23% and 28%, which meets the standard requirements, and the hardness (HR15N) is between 68 and 72, which is lower than the standard requirement of ≤75HR15N; and after aging treatment, the tensile strength (σb) of the alloy is increased to 1180MPa to 1199MPa, the yield strength (σ0.2) is increased to 901MPa to 921MPa, the elongation (δ5) is increased to between 6% and 11%, and the hardness is 38HRC to 41HRC, which shows that the aging treatment significantly improves the elongation of the GH141 alloy. Although the hardness is reduced, it is still better than the standard, especially in the yield strength and tensile strength. The alloy after aging treatment shows a significant improvement. The improvement in elongation also shows that the toughness of the alloy has been enhanced, which is more suitable for use under more demanding working conditions.

[0138] The above embodiments further prove that the present invention provides a method for manufacturing a precipitation-hardened nickel-based deformed high-temperature alloy GH141 cold-rolled thin plate, by reasonably designing the steps of steel ingot homogenization heat treatment, forging blanking, hot rolling and finishing rolling, semi-finished product heat treatment, pickling, cold rolling, finished product heat treatment and leveling, and accurately controlling key process parameters such as heating temperature, deformation amount, rolling temperature, cooling rate, etc., so that the alloy has excellent plastic deformation ability during the cold rolling process, and at the same time greatly improves the mechanical properties and surface quality of the finished thin plate. The present invention effectively improves the thermoplasticity and forgeability of the GH141 alloy and avoids the occurrence of cracking and hot working defects by optimizing the homogenization heat treatment and forging blanking process; improves the structural uniformity and dimensional accuracy of the plate by accurately controlling the hot rolling temperature and the final rolling cooling method; further ensures the surface quality and cold rolling deformation performance of the thin plate by coordinating the pickling and cold rolling processes; finally, by combining the solid solution heat treatment and rapid cooling technology, effectively solves the problems of grain growth and insufficient hardness, so that the finished plate exhibits excellent strength, plasticity and durability under both room temperature and high temperature conditions; the present invention significantly solves the technical difficulties existing in the prior art in the manufacture of GH141 alloy thin plates, such as poor hot working plasticity, substandard finished product performance, and easy cracking during the cold rolling process, and has the significant advantages of simple process operation, stable finished product quality, and excellent comprehensive performance, and provides important technical support for the localization and large-scale industrial production of precipitation-hardened nickel-based high-temperature alloy thin plates.

[0139] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0140] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for manufacturing a precipitation hardened nickel-based high-temperature alloy GH141 cold-rolled sheet, characterized in that: The following steps are involved: S1: High temperature homogenization heat treatment of steel ingot: Take GH141 alloy steel ingot and perform homogenization treatment to improve the thermoplasticity of the steel ingot; S2: Forging and blanking: The steel ingot is preheated, and then the preheated steel ingot is returned to the furnace to a temperature of 1200±20° C., and forged to obtain a billet; S3: Hot rolling treatment: The blank obtained after forging in step S2 is subjected to hot rolling and hot finishing rolling in sequence to obtain a semi-finished plate; the hot rolling temperature is 1210±20°C, and the hot finishing rolling final rolling temperature is greater than 950°C; S4: Heat treatment of semi-finished products: Performing solution heat treatment on the semi-finished plate obtained in step S3; S5: Pickling: The semi-finished plate treated in step S4 is pickled; S6: Cold rolling: Cold rolling the semi-finished plate obtained in step S5; Semi-finished products are cold rolled with large deformation, and finished products are cold rolled with multiple passes of small deformation to ensure plate shape and mechanical properties; S7: Finished product heat treatment: The finished plates are subjected to solution heat treatment, and the heating temperature, time and water exposure time are controlled. The water exposure time does not exceed 5 seconds, and they are cooled quickly to ensure material performance.

2. The method for manufacturing the precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled sheet according to claim 1, characterized in that: In the step S1, the homogenization treatment is carried out under the conditions of: treating at a temperature of 1170±20° C. for 6-7 hours, followed by cooling in the furnace.

3. The method for manufacturing the precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled sheet according to claim 1, characterized in that: In the step S2, the preheating condition is: preheating the steel ingot to 1200±20°C, and then coating the steel ingot with thermal insulation cotton.

4. The method for manufacturing the precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled thin plate according to claim 1, characterized in that: In step S3, the conditions for hot rolling are: heating the billet to 1180±10°C, keeping it warm for 1.5 hours, then taking it out of the furnace and wrapping it with insulation material, then putting the billet into a heating furnace, heating it to 1210±20°C, keeping it warm for 40 minutes, and then rolling it.

5. The method for manufacturing the precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled sheet according to claim 1, characterized in that: In step S3, the conditions for hot rolling and finishing rolling are: rolling is carried out by multiple heating, and the number of rolling passes in each heating is not more than 3, and the deformation of each pass is not less than 8%; the cooling method after rolling is single-piece separate cooling.

6. The method for manufacturing the precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled sheet according to claim 1, characterized in that: In step S4, the conditions of the solution heat treatment are: the solution temperature is 1080±10° C., and the solution time is less than 2 hours.

7. The method for manufacturing the precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled sheet according to claim 1, characterized in that: In step S5, the pickling conditions are: pickling is performed with sulfuric acid having a concentration of 45-50%, and the temperature of the sulfuric acid is 80-90°C.

8. The method for manufacturing the precipitation hardening nickel-based high-temperature alloy GH141 cold-rolled sheet according to claim 1, characterized in that: In step S6, the cold rolling process includes semi-finished product cold rolling and finished product cold rolling. The semi-finished product cold rolling includes: cold rolling the semi-finished product sheet by large deformation, and the deformation rate of the first three passes reaches more than 12%, and the total deformation rate of the rolling process is 30-35%; the finished product cold rolling is carried out after the semi-finished product cold rolling is completed, and the condition is: cold rolling the semi-finished product cold rolled sheet by small reduction and multiple passes.

9. The method for manufacturing the precipitation hardening nickel-based high temperature alloy GH141 cold-rolled sheet according to claim 1, characterized in that: In step S7, the temperature of the solution treatment is 1080±10°C, and after the solution treatment is completed and the plate is taken out of the furnace, it is water-cooled. The conditions of the water-cooling treatment are: the plate is water-cooled after it is taken out of the furnace, and the water-cooling treatment time is less than 5 seconds.

10. The method for manufacturing the precipitation hardening nickel-based high temperature alloy GH141 cold rolled sheet according to claim 1, characterized in that: After step S7 is completed, step S8 of flattening the finished product is further included, including: flattening the finished plate twice, and the total deformation rate of the two flattening treatments is ≤1%.

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