Preparation method of high-temperature-resistant acid corrosion medium titanium alloy plate

Abstract

The invention relates to the technical field of titanium and titanium alloy materials, in particular to a preparation method of a titanium alloy plate resistant to a high-temperature acid corrosion medium. 10-15 wt% of Mo element is introduced into a Ti matrix to optimize the electronic structure and the chemical composition of the passivation film, and no more than 0.2 wt% of rare earth element is added cooperatively to achieve smelting purification, reduce oxide inclusion and promote grain refinement. According to the method, a structure homogenization and multi-stage hot working process is constructed, and a fine, uniform and segregation-free plate structure is obtained, so that the stability, compactness and re-passivation capability of a passivation film are remarkably improved. The titanium alloy plate prepared by the method shows excellent pitting corrosion resistance, crevice corrosion resistance and stress corrosion resistance in high-temperature acidic and chloride ion-containing harsh corrosive media, is high in service stability, and can be widely applied to key components such as titanium steel composite plates, petrochemical equipment, heat exchangers, reactors and seawater desalination.

Description

Technical Field

[0001] This invention relates to the field of titanium and titanium alloy materials technology, specifically to a method for preparing titanium alloy plates resistant to high-temperature acidic corrosion media. The titanium alloy plates prepared by this method can be widely used in key equipment such as heat exchangers, coolers, reactors, electrolytic cell structural components, piping and valves in the chemical industry, and are especially suitable for complex corrosion conditions such as strong oxidizing, high-temperature acid and chloride ion-containing environments. Background Technology

[0002] Titanium and titanium alloys, due to their excellent corrosion resistance and high specific strength, have been widely used in the manufacture of chemical equipment. my country's chemical industry has long been the largest consumer of titanium materials, with applications including heat exchangers, coolers, reactors, electrolytic cell structural components, piping, and valves. With the rapid development of the chemical industry, the demand for titanium in the chemical sector continues to grow rapidly, holding a significant position in my country's materials market.

[0003] However, as chemical media expand towards more oxidizing, higher-temperature, and more complex industrial systems, traditional industrial pure titanium and some commercially available corrosion-resistant titanium alloys are highly susceptible to localized corrosion in high-temperature acidic environments, such as pitting corrosion, crevice corrosion, and stress corrosion cracking, leading to a significant reduction in service life. Existing titanium alloy systems specifically designed for high-temperature acidic corrosion environments remain very limited, failing to meet the stable service requirements under harsh corrosive conditions. Therefore, developing titanium alloys with superior resistance to high-temperature acidic corrosion and their preparation methods is a crucial technical problem urgently needing to be solved in the chemical industry.

[0004] Patent CN116516214A discloses a titanium alloy resistant to high-temperature nitric acid corrosion and its preparation method. Its alloy system is Ti-Pd-Al, relying on the precious metal Pd to enhance corrosion resistance, significantly increasing material costs and hindering large-scale industrial application. Its cast or simply machined products exhibit poor microstructure uniformity and coarse grains, making it impossible to achieve refined microstructure and excellent corrosion resistance in large-size plates, thus failing to meet the requirements of chemical equipment for a balance between mechanical properties and corrosion resistance. Patent CN115807879A discloses a titanium alloy oil well pipe resistant to hydrochloric acid and hydrofluoric acid corrosion and its processing method. Its corrosion resistance relies on a composite surface treatment of an electrodeposited alloy layer (such as nickel-tungsten-phosphorus or nickel-tungsten-iron), a leak-sealing layer, and a passivation layer. Corrosion protection is achieved through a surface coating, but the process involves multiple complex steps such as electrodeposition, dehydrogenation, and sealing. This not only results in high costs and long production cycles, but also makes the surface coating prone to peeling and cracking in high-temperature acidic environments, leading to substrate exposure and corrosion, thus preventing long-term stable service. The patent with publication number CN118106367A proposes a method to improve the corrosion resistance of Ni-containing titanium alloy plates. The Ti-Mo-Ni alloy relies on the precipitation of Ni compounds to improve corrosion resistance. Its corrosion resistance depends solely on the single effect of Ni. Moreover, at high temperatures, Ni compounds are easily dissolved and the precipitated phase grows, which leads to the destruction of the passivation film continuity and a significant decrease in corrosion resistance. Summary of the Invention

[0005] To address the problems of localized corrosion, insufficient service stability, and difficulty in balancing cost control and large-size plate forming of existing titanium and titanium alloy materials in high-temperature acidic corrosive media, the present invention aims to provide a method for preparing titanium alloy plates resistant to high-temperature acidic corrosive media. Based on the theory of sub-outer shell electron vacancies and the corrosion electrochemical passivation mechanism, the method significantly improves the corrosion resistance of titanium alloys in high-temperature strong acid environments by optimizing the Ti-(10~15 wt.%)Mo-(0~0.2 wt.%)RE (La, Ce, Pr, Nd, Sm, Ru) alloy system.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing titanium alloy plates resistant to high-temperature acidic corrosion media includes the following steps: (1) Determine the chemical composition of the titanium alloy: by weight percentage, the titanium alloy contains 10.0~15.0% Mo and rare earth elements with a total content not exceeding 0.2%, with the balance being Ti. The rare earth elements are one or more of La, Ce, Pr, Nd, Sm and Ru. (2) Raw material batching and smelting: Sponge titanium, Al bean, AlMo master alloy and TiRE master alloy are used as raw materials. They are weighed and batched according to the chemical composition ratio in step (1). After mixing, they are pressed into electrodes. The raw materials are smelted three times in a vacuum arc furnace to obtain a cylindrical ingot with a length of 1700 mm and a cross-sectional diameter of 380 mm. The ingot is peeled and ultrasonically tested. After the riser is removed, the β transformation temperature T of the alloy is determined by metallographic microscopy. β ; (3) High-temperature homogenization heat treatment: The ingot in step (2) is subjected to high-temperature homogenization heat treatment in a stepped resistance furnace. The treatment temperature is 1000~1150℃ and the holding time is 12~48h. (4) Upsetting and drawing deformation: The ingot after homogenization treatment in step (3) is subjected to one upsetting and drawing deformation at 1000℃~1150℃ using a 4500MN high-speed forging machine, with a deformation amount ≥25%; (5) Single-phase zone three-fire secondary three-brick three-draw deformation: The forging billet after the billet opening in step (4) is formed by using a 4500MN fast forging machine. β The forging process is carried out at 40~60℃ with three heat treatments, three upsettings, and three drawings. The rapid upsetting deformation is adopted with a forging frequency of ≥90 times / minute, the deformation amount per heat treatment is ≥25%, and the cumulative deformation amount is ≥75%. (6) Two-phase zone three-fire secondary three-brick three-draw deformation: The forging billet after the single-phase zone treatment in step (5) is subjected to three-stage deformation using a 4500MN high-speed forging machine. β - Perform three-stage upsetting and three-stage drawing deformation at (40~60)℃, using slow-speed upsetting deformation, with a forging frequency of 45~65 times / minute, a deformation amount of ≥25% per stage, and a cumulative deformation amount of ≥75%; (7) Slab shaping: The forging slab after the two-phase region treatment in step (6) is formed by using a 4500MN high-speed forging machine. β - The slab is shaped at (20~60)℃ and the ingot is forged into a slab with a thickness of 150mm; (8) Multi-pass hot rolling: The 150mm thick slab after grinding in step (7) is rolled in a hot rolling mill. β - Multiple hot rolling deformations are performed at (20~40)℃ to obtain plates with a thickness of 20~30mm.

[0007] In the method for preparing titanium alloy plates resistant to high-temperature acid corrosion media, in step (1), the weight percentage of Mo is 10.0%.

[0008] In the method for preparing titanium alloy plates resistant to high-temperature acid corrosion media, the weight percentage of rare earth elements in step (1) is 0.1%.

[0009] In the method for preparing titanium alloy plates resistant to high-temperature acidic corrosion media, step (2) involves ultrasonic testing to eliminate surface and internal defects.

[0010] In the method for preparing titanium alloy plates resistant to high-temperature acidic corrosion media, step (3) involves promoting the homogenization of alloy composition and structure through high-temperature homogenization heat treatment, thereby providing a uniform structure for subsequent forging processes.

[0011] In the method for preparing titanium alloy plates resistant to high-temperature acidic corrosion media, step (8) involves 5 to 15 passes of multi-pass hot rolling deformation, with each pass involving a deformation amount of 10 to 30%.

[0012] The design concept of this invention is: Studies based on corrosion electrochemistry and passivation film stability mechanisms have shown that alloying to regulate the composition and structure of the passivation film on titanium alloy surfaces is an effective way to improve their corrosion resistance. This invention proposes using β-stabilizing elements with d-shell electron vacancies, such as Mo, as the main alloying element, which can promote the formation of a more stable and resilient oxide film during passivation. Simultaneously, the introduction of rare earth elements can achieve a purification effect during smelting, reducing oxide inclusions and significantly refining the grain size by altering recrystallization behavior. The fine-grained structure facilitates the rapid and uniform formation of the passivation film, improving its density and repassivation ability, thereby significantly enhancing the corrosion resistance of titanium alloys in high-temperature acidic media. Furthermore, rare earth elements have a stronger affinity for oxygen, which is beneficial for improving the stability and dissolution resistance of the passivation film, providing more reliable protection for titanium alloys in complex corrosive environments.

[0013] 1. Alloy composition optimization design based on electronic structure regulation Based on the d-shell electron vacancy theory, this invention optimizes the electronic structure and chemical composition of the passivation film of the alloy by rationally introducing the β-stable element Mo with d-shell electron vacancies into the titanium matrix. This promotes the formation of a more stable, dense, and highly resistant passivation film in high-temperature acidic media, thereby enhancing the inherent corrosion resistance of the alloy at the micro-electrochemical level and laying a theoretical foundation for the long-term service of materials in extreme corrosive environments.

[0014] 2. Design of microstructure and passivation film stability enhanced by rare earth elements This invention introduces extremely low amounts of rare earth elements (including one or more of La, Ce, Pr, Nd, Sm, and Ru) into the alloy system. Utilizing the purification and deoxidation effects of rare earth elements during the smelting process, it effectively reduces the content of oxide inclusions and improves the purity of the matrix. Simultaneously, by controlling grain recrystallization behavior, it achieves a significant grain refinement effect, promoting the uniform formation of the passivation film and enhancing its repassivation capability. The strong binding tendency between rare earth elements and oxygen further improves the chemical stability and dissolution resistance of the passivation film, thereby achieving a synergistic enhancement of corrosion resistance and microstructure stability.

[0015] 3. Integrated process design based on microstructure homogenization and multi-stage thermal processing This invention achieves thorough homogenization of alloy composition and refined microstructure control through a systematic process route of "high-purity raw material preparation → multiple vacuum consumable arc melting → high-temperature homogenization heat treatment → staged forging and hot rolling." This is achieved through multi-pass deformation in both single-phase and two-phase regions, and T... β The nearby heat treatment process yields a fine, uniform, and segregation-free microstructure in the plate, which significantly improves the stability, density, and repassivation energy of the passivation film. This provides an ideal microstructure basis for the rapid nucleation and stable growth of the passivation film, thereby significantly improving the service stability and reliability of titanium alloy plates in high-temperature acidic corrosive media.

[0016] In summary, this invention achieves a significant improvement in the service performance of titanium alloys in high-temperature acidic corrosion environments by optimizing the composition design based on the d-layer electron vacancy theory (also known as the sub-outer layer electron vacancy theory, which optimizes the passivation film stability by regulating the d-layer electron vacancy structure) and the passivation film stability mechanism. It introduces Mo and specific rare earth elements to improve the composition and microstructure uniformity of the passivation film. Combined with homogenization melting and microstructure refinement hot working processes, this invention meets the application requirements of the chemical industry for high-reliability titanium alloy plates under harsh corrosive media conditions.

[0017] The advantages and beneficial effects of this invention are: 1. This invention introduces 10-15 wt.% Mo into the Ti matrix through alloy composition design based on the d-layer electron vacancy theory. By utilizing the Mo element to optimize the electronic structure and passivation film chemical composition, the stability and repassivation capability of the passivation film of titanium alloy in strong oxidizing and high-temperature acidic media are significantly improved, effectively inhibiting pitting corrosion, crevice corrosion and stress corrosion cracking, thereby greatly extending the service life of the material.

[0018] 2. This invention introduces trace amounts of rare earth elements (such as La, Ce, Pr, Nd, Sm, Ru) of no more than 0.2 wt.% to achieve inclusion purification and oxide removal during the smelting process, thereby improving the purity of the matrix. At the same time, it promotes grain refinement and microstructure homogenization, increases the passivation film formation rate and density, and enables the alloy to maintain excellent structural stability and corrosion resistance under complex corrosive environments.

[0019] 3. The titanium alloy plates prepared by the method described in this invention exhibit excellent service stability and reliability in high-temperature acidic and chloride-containing highly corrosive media. They can be widely used in key structural components in harsh corrosive environments such as titanium-steel composite plates, petrochemical equipment, chemical heat exchangers, reactors, and desalination devices, and have significant industrial promotion value.

[0020] 4. The alloy system of this invention is rationally designed, and the preparation process route is clear. It can be realized using conventional raw materials and mature equipment. Its process control is simple and the operation error tolerance is high. It not only significantly improves the controllability of composition and structure and the reproducibility of the preparation process, but also makes the method of this invention have excellent industrial application potential and mass production feasibility, making it suitable for large-scale promotion and application in the fields of chemical and materials manufacturing.

[0021] 5. The titanium alloy plates prepared by the method of this invention exhibit excellent resistance to pitting corrosion, crevice corrosion and stress corrosion in harsh corrosive media such as high-temperature acidic and chloride-containing media. They have high service stability and can be widely used in key components such as titanium-steel composite plates, petrochemical equipment, heat exchangers, reactors and seawater desalination. They have significant engineering application and industrialization promotion value. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the embodiments, but the present invention is not limited to these embodiments.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0024] In this invention, the β phase transformation temperature (Ti) of alloys with different compositions is determined by differential thermal analysis (DTA). β ): T of Ti-10Mo-0.1La alloy β The temperature range is 775~780 °C for the Ti-10Mo-0.1Nd alloy. βThe temperature range is 780~785 °C for the Ti-10Mo-0.1Ru alloy. β The temperature is 770~775℃.

[0025] The present invention will be further described in detail below through embodiments.

[0026] Example 1

[0027] In this embodiment, the method for preparing titanium alloy plates resistant to high-temperature acidic corrosion media includes the following steps: (1) The chemical composition of the titanium alloy by weight percentage is Mo: 10.0%; rare earth element La: 0.1% and the balance is Ti.

[0028] (2) Using sponge titanium, Al bean, AlMo master alloy, and TiRE master alloy as raw materials, the materials are weighed and batched according to the chemical composition ratio designed for the alloy. After thorough mixing, the materials are pressed into electrodes and smelted three times in a vacuum arc furnace according to the alloy composition prepared in step (1) to obtain a cylindrical ingot with uniform composition. The length of the ingot is 1700 mm and the diameter of the cross-section is 380 mm. The obtained ingot is peeled and ultrasonically tested to eliminate surface and internal defects. Then the riser part of the ingot is removed, and the β transformation temperature of the alloy is determined to be 775~780 ℃ using metallographic microscopy.

[0029] (3) The qualified ingots in step (2) are subjected to high-temperature homogenization heat treatment in a stepped resistance furnace. The treatment temperature is 1080℃ and the holding time is 24h, so as to promote the homogenization of alloy composition and structure and provide a uniform structure for subsequent forging processes.

[0030] (4) The ingot after homogenization in step (3) was subjected to one hot upsetting and drawing deformation at 1080℃ using a 4500MN fast forging machine with a deformation amount of 30.0%.

[0031] (5) The forging blank after the forging in step (4) is subjected to three-fire, three-up and three-draw deformation using a 4500MN fast forging machine. The temperature is controlled at 825~830 ℃. The forging is required to be fast upsetting, with a forging frequency of 150 times / minute, a deformation amount of 38.0% per fire, and a cumulative deformation amount of 76.2%.

[0032] (6) Using a 4500MN fast forging machine, the forging billet after three heatings, three upsettings and three drawings in the single-phase region in step (5) is subjected to three heatings, three upsettings and three drawings in the two-phase region. The temperature is controlled at 725~730℃. Slow upsetting deformation is required, the forging frequency is 50 times / minute, the deformation per heating is 45.0%, and the cumulative deformation is 85.3%.

[0033] (7) The forging billet after three heatings, three stackings and three drawings in the two-phase region in step (6) is finally shaped into a slab using a 4500MN fast forging machine. The temperature is controlled at 735~740℃. Finally, the ingot with a length of 1700 mm and a cross-sectional diameter of 380 mm is forged into a slab with a thickness of 150 mm.

[0034] (8) The 150 mm thick slab after grinding in step (7) is hot rolled in 9 passes using a hot rolling mill to obtain a 25 mm thick plate. The temperature is controlled at 745~750℃.

[0035] Example 2

[0036] In this embodiment, the method for preparing titanium alloy plates resistant to high-temperature acidic corrosion media includes the following steps: (1) The chemical composition of the titanium alloy by weight percentage is Mo: 10.0%; rare earth element Nd: 0.1% and the balance is Ti.

[0037] (2) Using sponge titanium, Al bean, AlMo master alloy, and TiRE master alloy as raw materials, the materials are weighed and batched according to the chemical composition ratio designed for the alloy. After thorough mixing, the materials are pressed into electrodes and smelted three times in a vacuum arc furnace according to the alloy composition prepared in step (1) to obtain a cylindrical ingot with uniform composition. The length of the ingot is 1700 mm and the diameter of the cross-section is 380 mm. The obtained ingot is peeled and ultrasonically tested to eliminate surface and internal defects. Then the riser part of the ingot is removed, and the β transformation temperature of the alloy is determined to be 780~785 ℃ using metallographic microscopy.

[0038] (3) The qualified ingots in step (2) are subjected to high-temperature homogenization heat treatment in a stepped resistance furnace. The treatment temperature is 1030℃ and the holding time is 48h, so as to promote the homogenization of alloy composition and structure and provide a uniform structure for subsequent forging processes.

[0039] (4) The ingot after homogenization in step (3) was subjected to one-time upsetting and drawing deformation at 1030℃ using a 4500MN fast forging machine with a deformation amount of 35%.

[0040] (5) The forging billet after the forging in step (4) is subjected to three-fire, three-up, and three-drawing deformation using a 4500MN fast forging machine. The temperature is controlled at 820~825℃. The forging is required to be fast-rate upsetting deformation, with a forging frequency of 120 times / minute, a deformation amount of 40.0% per fire, and a cumulative deformation amount of 78.4%.

[0041] (6) Using a 4500MN fast forging machine, the forging billet after three heatings, three upsettings and three drawings in the single-phase region in step (5) is subjected to three heatings, three upsettings and three drawings in the two-phase region. The temperature is controlled at 740~745℃. Slow upsetting deformation is required, the forging frequency is 40 times / minute, the deformation per heating is 48.0%, and the cumulative deformation is 86.0%.

[0042] (7) The forging billet after three heatings, three stackings and three drawings in the two-phase region in step (6) is finally shaped into a slab using a 4500MN fast forging machine. The temperature is controlled at 720~725℃. Finally, the ingot with a length of 1700 mm and a cross-sectional diameter of 380 mm is forged into a slab with a thickness of 150 mm.

[0043] (8) The 150 mm thick slab after grinding in step (7) is hot rolled in 10 passes using a hot rolling mill to obtain a 30 mm thick plate. The temperature is controlled at 740~745℃.

[0044] Example 3

[0045] In this embodiment, the method for preparing titanium alloy plates resistant to high-temperature acidic corrosion media includes the following steps: (1) The chemical composition of the titanium alloy by weight percentage is Mo: 10.0%; rare earth element Ru: 0.1% and the balance is Ti.

[0046] (2) Using sponge titanium, Al bean, AlMo master alloy, and TiRE master alloy as raw materials, the materials are weighed and batched according to the chemical composition ratio designed for the alloy. After thorough mixing, the materials are pressed into electrodes and smelted three times in a vacuum arc furnace according to the alloy composition prepared in step (1) to obtain a cylindrical ingot with uniform composition. The length of the ingot is 1700 mm and the diameter of the cross-section is 380 mm. The obtained ingot is peeled and ultrasonically tested to eliminate surface and internal defects. Then the riser part of the ingot is removed, and the β transformation temperature of the alloy is determined to be 770~775℃ using metallographic microscopy.

[0047] (3) The qualified ingots in step (2) are subjected to high-temperature homogenization heat treatment in a stepped resistance furnace. The treatment temperature is 1120℃ and the holding time is 12h, so as to promote the homogenization of alloy composition and structure and provide a uniform structure for subsequent forging processes.

[0048] (4) The ingot after homogenization in step (3) was subjected to one-time upsetting and drawing deformation at 1120℃ using a 4500MN fast forging machine, with a deformation amount of 40.0%.

[0049] (5) The forging blank after the forging in step (4) is subjected to three-fire, three-up, and three-draw deformation using a 4500MN fast forging machine. The temperature is controlled at 830~835℃. The forging is required to be fast-rate upsetting deformation, with a forging frequency of 100 times / minute, a deformation amount of 42.0% per fire, and a cumulative deformation amount of 80.5%.

[0050] (6) Using a 4500MN fast forging machine, the forging billet after three heatings, three upsettings and three drawings in the single-phase region in step (5) is subjected to three heatings, three upsettings and three drawings in the two-phase region. The temperature is controlled at 710~715℃. Slow upsetting deformation is required, the forging frequency is 60 times / minute, the deformation per heating is 50.0%, and the cumulative deformation is 87.5%.

[0051] (7) The forging billet after three heatings, three stackings and three drawings in the two-phase region in step (6) is finally shaped into a slab using a 4500MN fast forging machine. The temperature is controlled at 750~755℃. Finally, the ingot with a length of 1700 mm and a cross-sectional diameter of 380 mm is forged into a slab with a thickness of 150 mm.

[0052] (8) The 150 mm thick slab after grinding in step (7) is hot rolled in 11 passes using a hot rolling mill to obtain a 20 mm thick plate. The temperature is controlled at 750~755℃.

[0053] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in step (1), the chemical composition of the titanium alloy by weight percentage is Mo: 8.0%; rare earth element La: 0.5% and the balance is Ti; the rest of the operation is the same, and finally a titanium alloy plate with a thickness of 25mm and resistant to high temperature acid corrosion medium is obtained.

[0054] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the three-fire, three-brick, and three-drawing process is not used. Instead, ordinary forging deformation is performed. After completing step (4), step (7) is performed directly. The remaining operations are the same, and a titanium alloy plate with a thickness of 25mm and resistance to high-temperature acid corrosion media is finally obtained.

[0055] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that rare earth elements are not used in the titanium alloy raw materials. That is, the chemical composition and mass percentage of the titanium alloy ingot are: Mo 15.0%; the balance is Ti. The remaining operations are the same as in Example 1, and finally a titanium alloy plate with a thickness of 25 mm and resistant to high temperature acid corrosion media is obtained.

[0056] Table 1 Comparison of weight loss results of materials in Examples 1-3 and Comparative Examples 1-3 in high-temperature hydrochloric acid at 25℃ and 100℃.

[0057] The experimental results above show that titanium alloy plates resistant to high-temperature acidic corrosion media can be prepared using the preparation method specified in this invention.

[0058] Comparing Examples 1-3 with Comparative Example 1, it can be seen that the weight loss of the finished titanium alloy sheet prepared in Comparative Example 1 under hydrochloric acid conditions at 25℃ and 100℃ is much greater than that in Examples 1-3. The greater the weight loss, the more severe the corrosion and the worse the corrosion resistance in the high-temperature acidic medium. Therefore, this invention is based on the d-layer electron vacancy theory. By rationally introducing the β-stabilizing element Mo with d-layer electron vacancies into the titanium matrix, the electronic structure of the alloy and the chemical composition of the surface passivation film are optimized. This promotes the formation of a more stable, dense, and highly resistant passivation film in the high-temperature acidic medium, thereby improving the inherent corrosion resistance of the alloy at the microscopic electrochemical level and endowing the alloy with continuous corrosion resistance under high-temperature conditions.

[0059] Comparing Examples 1-3 and Comparative Example 2, it can be seen that although the weight loss of Comparative Example 2 under 25℃ hydrochloric acid conditions is slightly smaller than that of Examples 1-3, the weight loss of the finished titanium alloy sheet prepared by Comparative Example 2 under 100℃ hydrochloric acid conditions is much larger than that of Examples 1-3. Therefore, it can be seen that this invention achieves full homogenization of alloy composition and refined control of microstructure by constructing a systematic process route of "high-purity raw material preparation—multiple vacuum self-consuming arc melting—high-temperature homogenization heat treatment—staged forging and hot rolling forming". Through multi-pass deformation in the single-phase and two-phase regions and T... β The nearby heat treatment process yields a fine, uniform, and segregation-free plate microstructure, providing an ideal microstructure basis for the rapid nucleation and stable growth of the passivation film.

[0060] Comparing Examples 1-3 and Comparative Example 3, it can be seen that although the weight loss value of Comparative Example 3 under hydrochloric acid conditions at 25℃ is slightly smaller than that of Examples 1-3, the weight loss value of the finished titanium alloy plate prepared by Comparative Example 3 under hydrochloric acid conditions at 100℃ is much larger than that of Examples 1-3. This shows that the present invention introduces extremely low amounts of rare earth elements (including one or more of La, Ce, Pr, Nd, Sm, and Ru) into the alloy system, and utilizes the purification and deoxidation effects of rare earth elements during the smelting process to effectively reduce the content of oxide inclusions and improve the purity of the matrix. At the same time, by controlling the grain recrystallization behavior, a significant grain refinement effect is achieved, which promotes the uniform formation of the passivation film and improves the repassivation capability. The strong binding tendency between rare earth elements and oxygen elements further improves the chemical stability and anti-dissolution performance of the passivation film.

[0061] The results show that this invention optimizes the electronic structure by using 10-15 wt.% Mo, promoting the formation of a stable passivation film in high-temperature acidic media, effectively inhibiting pitting corrosion, crevice corrosion, and stress corrosion cracking. The purification and grain refinement effects of rare earth elements further improve the passivation film formation rate and density, ensuring long-term stable service of the alloy in complex media such as high-temperature acidic and chloride-containing media, significantly extending the material's service life. The combination of staged forging and hot rolling processes ensures uniform composition and refined microstructure in large-size plates, avoiding compositional segregation and microstructure inhomogeneity during forming. The plates exhibit excellent uniformity in mechanical properties and corrosion resistance, meeting the requirements of chemical equipment for large-size titanium alloy plates.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of producing a titanium alloy plate material resistant to high-temperature acid corrosive media, characterized by, The method comprises the following steps: (1) determining the chemical composition of the titanium alloy: the titanium alloy contains Mo 10.0-15.0% and rare earth elements with a total content of not more than 0.2% by weight, and the balance is Ti, and the rare earth elements are one or more than two of La, Ce, Pr, Nd, Sm and Ru; (2) Raw material batching and melting: taking sponge titanium, Al beans, AlMo intermediate alloy, TiRE intermediate alloy as raw materials, batching and weighing according to the chemical composition proportion of step (1), pressing into an electrode after mixing, and adopting vacuum consumable arc furnace to melt the raw materials for three times to obtain a cylindrical ingot with a length of 1700 mm and a cross-sectional diameter of 380 mm; after skinning treatment and ultrasonic flaw detection of the ingot, the beta transus temperature T β of the alloy is determined by metallographic microscopic method after cutting off the riser; (3) high-temperature homogenization heat treatment: a step resistance furnace is used to perform high-temperature homogenization heat treatment on the ingot in step (2), the treatment temperature is 1000-1150℃, and the holding time is 12-48h; (4) upsetting and drawing deformation: a 4500MN fast forging machine is used to perform 1-time upsetting and drawing deformation on the homogenization treated ingot in step (3) at 1000-1150℃, and the deformation amount is ≥25%; (5) Single-phase zone three-fire three-dump three-pull deformation: using 4500MN fast forging machine to deform the forged blank after step (4) in T β + (40~60) ℃ for three-fire three-dump three-pull deformation, using fast rate upsetting deformation, forging frequency ≥ 90 times / minute, deformation per fire ≥ 25%, cumulative deformation ≥ 75%; (6) Two-phase zone three-fire three-dump three-pull deformation: using 4500MN fast forging machine to carry out three-fire three-dump three-pull deformation on the forging blank treated in step (5) in T β - (40~60) ℃, three-fire three-dump three-pull deformation is carried out, slow rate upsetting deformation is adopted, the forging frequency is 45~65 times / minute, the deformation per fire is ≥25%, and the cumulative deformation is ≥75%. (7) slab forming: using a 4500 MN fast forging machine to forge the ingot in step (6) after two-phase region treatment at T β - (20-60) °C to perform slab forming, and forging the ingot into a slab with a thickness of 150 mm; (8) Multi-pass hot rolling: using a hot rolling mill to hot roll the 150 mm thick plate blank after grinding in step (7) at T β - (20~40) °C to deform by multi-pass hot rolling to obtain a plate with a thickness of 20~30 mm.

2. The method of producing a titanium alloy plate for high-temperature acid corrosion-resistant medium according to Claim 1, characterized by In step (1), the weight percentage of Mo is 10.0%.

3. The method of claim 1, wherein the titanium alloy plate is prepared by the steps of: preparing a titanium alloy ingot by vacuum arc melting; hot forging the titanium alloy ingot; cold rolling the hot forged titanium alloy ingot; and annealing the cold rolled titanium alloy ingot. In step (1), the weight percentage of rare earth elements is 0.1%.

4. The method of claim 1, wherein the titanium alloy plate for high-temperature acid corrosion-resistant medium is characterized by In step (2), surface and internal defects are excluded by ultrasonic flaw detection.

5. The method of producing a titanium alloy plate for high-temperature acid corrosion-resistant medium according to Claim 1, characterized by In step (3), high-temperature homogenization heat treatment is used to promote the homogenization of alloy composition and organization, and provide uniform organization for subsequent forging process.

6. The method of producing a titanium alloy plate for high-temperature acid corrosion-resistant medium according to Claim 1, characterized by, In step (8), the multi-pass hot rolling deformation is 5-15 passes, and the deformation amount of each pass is 10-30%.

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