A rolling method for suppressing edge cracking in a titanium alloy rolling process

Abstract

This invention relates to the field of titanium alloy processing technology, specifically to a rolling method for suppressing edge cracks during the rolling process of titanium alloys. The method for suppressing edge cracks during the rolling process of titanium alloys is as follows: A titanium alloy sheet is placed in a first U-shaped fixture with an interference fit, and then subjected to large-reduction cold rolling. Afterwards, the first U-shaped fixture is removed to obtain a pre-rolled sheet. The pre-rolled sheet is then placed in a second U-shaped fixture with an interference fit, and then subjected to small-reduction cold rolling. The second U-shaped fixture is then removed to obtain a cold-rolled titanium alloy sheet. The reduction per pass in the small-reduction cold rolling is 2%–5%, and the total reduction is 10%–20%. This invention uses a fixture to constrain the edges of the titanium alloy sheet to be cold-rolled, which can effectively suppress the generation of edge cracks during the cold rolling process. Furthermore, by controlling the reduction per pass and the total reduction in the small-reduction cold rolling, the generation of edge cracks can be further suppressed.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy processing technology, and more specifically, to a rolling method for suppressing edge cracks during the rolling process of titanium alloys. Background Technology

[0002] Titanium alloys are widely used in aerospace, automotive, and shipbuilding industries due to their excellent properties of being lightweight, high-strength, heat-resistant, and corrosion-resistant. Cold rolling of titanium alloys is a processing method that alters the shape and size of a metal by applying pressure below its recrystallization temperature. As an important metal processing method, cold rolling offers advantages such as improved material strength, enhanced surface quality, and the ability to achieve complex shapes. This process is crucial for achieving plastic deformation of titanium alloy sheets and manufacturing ultra-thin titanium foils and sheets. By controlling the deformation amount and process parameters, the microstructure and mechanical properties of titanium alloys can be significantly influenced. Furthermore, cold rolling plays a vital role in improving the strength and hardness of titanium alloys and enhancing their plasticity.

[0003] However, edge cracking is a common defect in cold-rolled titanium alloys and requires close attention. During cold rolling, the titanium alloy is rolled between two or more rolls in a rolling mill. The gap between the rolls gradually decreases, resulting in a gradual reduction in material thickness. Titanium alloy sheets undergo varying degrees of strain hardening during rolling, leading to a decrease in material toughness, especially noticeable at the thinner edges. Increasing the rolling speed leads to a higher deformation rate, but excessively high speeds can cause localized stress concentration, increasing the risk of edge cracking. Furthermore, uneven roll contact or uneven initial material conditions can cause excessive stress in the edge areas, potentially triggering cracks.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a method for suppressing edge cracks during the rolling process of titanium alloys. By employing a fixture to constrain the edges of the titanium alloy sheet to be cold-rolled, the generation of edge cracks during the cold rolling process can be effectively suppressed, thereby improving the overall quality of the cold-rolled titanium alloy sheet. This solves the problem of edge cracking in titanium alloys caused by existing cold rolling technologies. Furthermore, this invention can further suppress the generation of edge cracks by controlling the rolling reduction per pass and the total rolling reduction in small-reduction cold rolling.

[0006] The second objective of this invention is to provide a method for preparing titanium alloy rolled products.

[0007] The third objective of this invention is to provide a method for suppressing edge cracks during the rolling process of titanium alloys or a method for preparing titanium alloy rolled parts, and its application in the preparation of titanium alloy products.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] This invention first provides a method for suppressing edge cracks during the rolling process of titanium alloys, comprising the following steps: placing a titanium alloy sheet in a first U-shaped fixture for edge restraint, wherein the titanium alloy sheet and the first U-shaped fixture are interference-fitted and the first U-shaped fixture covers the titanium alloy sheet, and then performing large-reduction cold rolling, followed by removing the first U-shaped fixture to obtain a pre-rolled sheet; placing the pre-rolled sheet in a second U-shaped fixture for edge restraint, wherein the pre-rolled sheet and the second U-shaped fixture are interference-fitted and the second U-shaped fixture covers the pre-rolled sheet, and then performing small-reduction cold rolling, followed by removing the second U-shaped fixture to obtain a cold-rolled titanium alloy sheet; wherein the cross-sectional shape of both the first U-shaped fixture and the second U-shaped fixture is U-shaped; the reduction per pass of the small-reduction cold rolling is 2% to 5%, and the total reduction of the small-reduction cold rolling is 10% to 20%.

[0010] Furthermore, the height of the first U-shaped clamp is equal to the height of the titanium alloy plate.

[0011] Furthermore, the height of the second U-shaped clamp is equal to the height of the pre-rolled sheet.

[0012] Furthermore, the dimensions of the bottom surface and two sides of the first U-shaped clamp are matched with the dimensions of the titanium alloy sheet.

[0013] Furthermore, the dimensions of the bottom surface and two sides of the second U-shaped fixture are matched with the dimensions of the pre-rolled sheet material.

[0014] Furthermore, the titanium alloy sheet includes at least one of TC4 titanium alloy sheet and Ti80 titanium alloy sheet.

[0015] Furthermore, the reduction per pass in the large reduction cold rolling is 5% to 12%.

[0016] Furthermore, the rolling rate of the large reduction cold rolling is 0.01 to 2 m / s.

[0017] Furthermore, the total rolling reduction of the large reduction cold rolling is 20% to 60%.

[0018] Furthermore, a rolling lubricant is used in each rolling pass of the large reduction cold rolling process.

[0019] Furthermore, the reduction per pass in the small reduction cold rolling is 2% to 5%.

[0020] Furthermore, the rolling rate of the small reduction cold rolling is 0.01 to 2 m / s.

[0021] Furthermore, the total rolling reduction of the small-reduction cold rolling is 10% to 20%.

[0022] Furthermore, a rolling lubricant is used in each rolling pass of the small reduction cold rolling process.

[0023] Furthermore, before placing the titanium alloy sheet in the first U-shaped fixture, the titanium alloy sheet undergoes a homogenization treatment.

[0024] Furthermore, the homogenization treatment method includes: coating a high-temperature glass protective agent onto a titanium alloy sheet, and after the high-temperature glass protective agent solidifies, heat-treating it at 700-1000℃ for 10-120 minutes, followed by annealing at 850℃ for 1.5 hours, and air cooling.

[0025] The present invention further provides a method for preparing titanium alloy rolled parts, including the method for suppressing edge cracks generated during the titanium alloy rolling process.

[0026] Furthermore, the preparation method of the titanium alloy plate includes: hot rolling a thick titanium alloy plate.

[0027] Furthermore, the heating temperature of the hot rolling is 900–1040°C, and the holding time is 0.1–20 h.

[0028] Furthermore, the hot rolling speed is 0.1 to 5 m / s.

[0029] Furthermore, the reduction per pass in the hot rolling is 10% to 12%.

[0030] Furthermore, the hot rolling process involves 5 to 30 rolling passes.

[0031] Furthermore, prior to the hot rolling, a high-temperature anti-oxidant is coated onto the titanium alloy thick plate.

[0032] Furthermore, after hot rolling, the process also includes cutting, pickling, and sandblasting steps.

[0033] The present invention also provides the application of the method for suppressing edge cracks during the rolling process of titanium alloys or the method for preparing titanium alloy rolled parts in the preparation of titanium alloy products.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) The method for suppressing edge cracks during the rolling process of titanium alloys provided by the present invention, by pre-setting the edge cracks that appear in the original titanium alloy sheet or the sheet after initial rolling during cold rolling onto the first U-shaped fixture and the second U-shaped fixture, can effectively suppress the generation of edge cracks during the cold rolling process of titanium alloys, thereby improving the overall quality of the cold-rolled titanium alloy sheet. At the same time, the present invention can further suppress the generation of edge cracks by controlling the rolling reduction of each pass and the total rolling reduction of small reduction cold rolling.

[0036] (2) The method for suppressing edge cracks in the rolling process of titanium alloy provided by the present invention controls the degree of material deformation by optimizing rolling parameters, which can further reduce the risk of plate cracking and effectively improve the plastic deformation capacity of titanium alloy plate, obtain uniform and fine grain structure, and obtain excellent mechanical properties.

[0037] (3) The titanium alloy cold-rolled sheet obtained by the method of suppressing edge cracks in the titanium alloy rolling process provided by the present invention has good microstructure uniformity, reduces internal structural defects of the material, obtains fine grain size, and improves the strength and hardness of the titanium alloy cold-rolled sheet, thus improving the overall toughness of the titanium alloy cold-rolled sheet.

[0038] (4) By using the method provided by the present invention to suppress edge cracks in the rolling process of titanium alloys, titanium alloy cold rolling can be carried out to obtain crack-free titanium alloy cold rolling sheet, which helps to reduce the scrap rate and rework rate of titanium alloy sheet and reduce production costs. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the structure of the first U-shaped clamp and the second U-shaped clamp provided by the present invention;

[0041] Figure 2 A cross-sectional schematic diagram of the first U-shaped clamp and the second U-shaped clamp provided by the present invention;

[0042] Figure 3 An image of the titanium alloy rolled product obtained in Example 1 of this invention;

[0043] Figure 4 Image of the titanium alloy rolled product obtained in Comparative Example 1 provided by the present invention;

[0044] Figure 5 The image shows a titanium alloy rolled piece obtained in Comparative Example 2 provided by this invention. Detailed Implementation

[0045] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0046] Unless otherwise specified, in this invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0047] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0048] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0049] In a first aspect, the present invention provides a method for suppressing edge cracks generated during the rolling process of titanium alloys, or a forming method for suppressing cold rolling cracks in titanium alloys using an edge constraint method, comprising the following steps:

[0050] A titanium alloy sheet is placed in a first U-shaped fixture for edge constraint, wherein the titanium alloy sheet and the first U-shaped fixture are interference-fitted, and the first U-shaped fixture covers the titanium alloy sheet. Then, a large reduction cold rolling process is performed. Afterwards, the broken first U-shaped fixture is removed to obtain the pre-rolled sheet. That is, the inner diameter of the first U-shaped fixture and the size of the titanium alloy sheet are interference-fitted. Furthermore, on each contact surface between the first U-shaped fixture and the titanium alloy sheet, the first U-shaped fixture covers the titanium alloy sheet.

[0051] The pre-rolled sheet is placed in a second U-shaped fixture for edge constraint, wherein the pre-rolled sheet and the second U-shaped fixture are interference-fitted, and the second U-shaped fixture covers the pre-rolled sheet. Then, it undergoes small-reduction cold rolling, and the second U-shaped fixture is removed to obtain a cold-rolled titanium alloy sheet. Specifically, the inner diameter of the second U-shaped fixture is interference-fitted with the size of the pre-rolled sheet. Furthermore, on each contact surface between the second U-shaped fixture and the pre-rolled sheet, the second U-shaped fixture covers the titanium alloy sheet.

[0052] The first U-shaped clamp and the second U-shaped clamp both have a U-shaped cross-section. The first U-shaped clamp and the second U-shaped clamp are collectively referred to as clamps. It can be understood that the clamp has a bottom surface and two side surfaces connected to the two ends of the bottom surface. The bottom surface and the two side surfaces together form a cuboid (or plate-like) accommodating space for accommodating the titanium alloy sheet to be cold rolled or the sheet after initial rolling.

[0053] Among them, the U-shaped clamps will not stick to the sheet metal during the cold rolling process. However, if it is fully covered, on the one hand, an interference fit cannot be achieved, and on the other hand, metal-to-metal adhesion is likely to occur.

[0054] like Figure 1 The diagram shows a three-dimensional structural schematic of the first U-shaped clamp and the second U-shaped clamp.

[0055] like Figure 2 The diagram shows a cross-sectional view of the first U-shaped clamp and the second U-shaped clamp.

[0056] See Figure 2 As shown, the fixture and the titanium alloy sheet to be cold-rolled or the sheet after initial rolling are fitted with an interference fit in the RD×TD direction (i.e., the fixture and the titanium alloy sheet or the sheet after initial rolling are fitted with an interference fit on the rolling side). During the interference fit process, the titanium alloy sheet to be cold-rolled or the sheet after initial rolling is combined with the fixture using external force. During the combination process, the fixture may undergo slight deformation due to its structure, thus achieving an interference fit between the titanium alloy sheet to be cold-rolled or the sheet after initial rolling and the fixture.

[0057] The method for suppressing edge cracks during the rolling process of titanium alloys provided by this invention involves setting up a first U-shaped clamp and a second U-shaped clamp (collectively referred to as clamps). During cold rolling, the clamps and the titanium alloy sheet or the sheet after initial rolling are simultaneously subjected to cold rolling deformation. This interference fit edge constraint method can effectively transfer rolling stress to the clamps during cold rolling, protecting the edges of the titanium alloy workpiece. By pre-setting the edge cracks that appear on the original titanium alloy sheet or the sheet after initial rolling during cold rolling onto the clamps, protective rolling of the titanium alloy sheet is achieved, effectively suppressing the generation of cracks during the cold rolling process of titanium alloys.

[0058] Meanwhile, this invention, by using a U-shaped clamp in conjunction with a large reduction cold rolling process during the first use of the U-shaped clamp, and then replacing the U-shaped clamp and using it again with a small reduction cold rolling process, can effectively improve and enhance the plastic deformation capacity of titanium alloy sheets, obtain a uniform and refined grain structure, avoid stress concentration during cold rolling leading to edge cracks, and obtain cold-rolled titanium materials with excellent mechanical properties.

[0059] The reduction per pass in the small-reduction cold rolling is 2% to 5%, including but not limited to any one of 2%, 3%, 4%, 5%, and 6%, or a range between any two. The total reduction in the small-reduction cold rolling is 10% to 20%, for example, 13%, 15%, or 18%. By controlling the reduction per pass and the total reduction in the small-reduction cold rolling, this invention can further suppress the generation of edge cracks.

[0060] In some specific embodiments, the height (inner diameter height, or accommodating space height) of the first U-shaped clamp is equal to the height of the titanium alloy sheet.

[0061] In some specific embodiments, the height (inner diameter height, or accommodating space height) of the second U-shaped clamp is equal to the height of the pre-rolled sheet.

[0062] In some specific embodiments, the dimensions of the bottom surface and two sides of the first U-shaped clamp are matched with the dimensions of the titanium alloy sheet. That is, the bottom surface of the first U-shaped clamp completely covers the bottom surface of the titanium alloy sheet it contacts, and the two sides of the first U-shaped clamp completely cover the sides of the titanium alloy sheet it contacts.

[0063] In some specific embodiments, the dimensions of the bottom surface and two sides of the second U-shaped clamp are matched with the dimensions of the pre-rolled sheet. That is, the bottom surface of the second U-shaped clamp completely covers the bottom surface of the pre-rolled sheet it contacts, and the two sides of the second U-shaped clamp completely cover the sides of the pre-rolled sheet it contacts.

[0064] During cold rolling, edge cracks may appear on the fixture, thus suppressing cracking in the edge-constrained titanium alloy sheet. The fixture dimensions are matched with the dimensions of the titanium alloy sheet or the sheet after initial rolling, which can effectively suppress edge cracks.

[0065] In some specific embodiments, the titanium alloy sheet includes, but is not limited to, at least one of TC4 titanium alloy sheet and Ti80 titanium alloy sheet. TC4 titanium alloy refers to Ti-6Al-4V titanium alloy.

[0066] The method for suppressing edge cracks during the rolling process of titanium alloys provided by this invention is applicable to various titanium alloys, including but not limited to TC4 titanium alloy. It is understood that parameters such as the pre-reduction and rolling rate will differ for different types of titanium alloys. Taking TC4 titanium alloy as an example, this invention, by controlling parameters such as the pre-reduction and rolling rate, can further suppress the generation of edge cracks and improve the mechanical properties of the resulting cold-rolled titanium alloy sheet.

[0067] Edge cracking is typically closely related to parameters such as rolling reduction and rolling rate. Changes in these parameters directly affect the stress state, deformation behavior, and final processing quality of the material. To reduce edge cracking during cold rolling, this invention optimizes rolling deformation parameters, such as rolling reduction per pass, rolling rate, and total rolling reduction, to control the degree of material deformation, thereby reducing the risk of plate cracking.

[0068] In some specific embodiments, the reduction per pass of the large reduction cold rolling is 5% to 12%; including but not limited to any one of 5%, 6%, 7%, 8%, 9%, 10%, 10.5%, 11%, 11.5%, 12% or any range between two.

[0069] In some specific embodiments, the rolling rate of the large reduction cold rolling is 0.01 to 2 m / s; including but not limited to any point value or a range between any two of 0.01 m / s, 0.05 m / s, 0.08 m / s, 1 m / s, 1.3 m / s, 1.5 m / s, 1.6 m / s, 1.7 m / s, 1.8 m / s, 1.9 m / s, and 2 m / s. The unit m / s is meters per second.

[0070] In some specific embodiments, the total rolling reduction of the large reduction cold rolling is 20% to 60%; including but not limited to any one of 20%, 30%, 40%, 50%, 51%, 52%, 53%, 55%, 56%, 58%, 60% or any range between two.

[0071] In some specific implementations, the thickness of the sheet is measured after each rolling pass to precisely control the reduction during rolling.

[0072] In some specific implementations, a rolling lubricant is used in each pass of the large reduction cold rolling process to improve the surface quality of the rolled piece.

[0073] The rolling lubricant includes, but is not limited to, any reagent commonly used in the art, such as cold rolling lubricants for titanium and titanium alloy foils.

[0074] In some specific embodiments, the rolling rate of the small reduction cold rolling is 0.01 to 2 m / s; including but not limited to any one of 0.01 m / s, 0.05 m / s, 0.08 m / s, 1 m / s, 1.3 m / s, 1.5 m / s, 1.6 m / s, 1.7 m / s, 1.8 m / s, 1.9 m / s, and 2 m / s, or a range between any two.

[0075] This invention can further reduce the risk of edge cracking by controlling the rolling rate during the cold rolling process.

[0076] While a large rolling reduction can promote grain breakage, refine the microstructure, and enhance the mechanical properties of the rolled product, incomplete grain breakage during the rolling process of titanium alloys can lead to internal stress concentration, increasing the risk of edge crack formation. This invention effectively reduces the risk of edge crack formation by using fixtures to constrain the edges of the cold-rolled sheet and controlling the rolling reduction in each pass and the total rolling reduction during cold rolling.

[0077] Furthermore, in this invention, when using the first U-shaped clamp, multiple passes with large reductions are employed until the total reduction reaches 20%–60%, at which point the second U-shaped clamp is used. When using the second U-shaped clamp, a multiple-pass, small-reduction cold rolling process is employed until the total reduction from both rolling passes reaches 80%–90%. This cold rolling process effectively improves and enhances the plastic deformation capacity of titanium alloy sheets, obtains a uniform and refined grain structure, avoids stress concentration leading to edge cracks during cold rolling, and yields cold-rolled titanium materials with excellent mechanical properties.

[0078] In some specific embodiments, a rolling lubricant is used in each rolling pass of the small reduction cold rolling process to improve the surface quality of the rolled piece, increase the surface cleanliness of the rolled piece, and reduce surface defects such as scratches, pits, and roll marks.

[0079] The rolling lubricant includes, but is not limited to, any reagent commonly used in the art, such as cold rolling lubricants for titanium and titanium alloy foils.

[0080] In some specific embodiments, after removing the second U-shaped clamp, the obtained cold-rolled part is sandblasted to remove the rolling lubricant from the surface of the part.

[0081] In some specific embodiments, before placing the titanium alloy sheet in the first U-shaped fixture, the titanium alloy sheet undergoes a homogenization treatment to achieve a uniform microstructure. This homogenization treatment improves the microstructure and properties of the titanium alloy, providing a better material condition for subsequent cold rolling.

[0082] In some specific embodiments, the homogenization treatment method includes coating a titanium alloy sheet with a high-temperature glass protective agent to prevent oxidation. The high-temperature glass protective agent includes any reagent commonly used in the art, such as SA-35, FR35, GDS-17, GHJD, etc., but is not limited thereto.

[0083] After the high-temperature glass protective agent solidifies, it is placed in a furnace and heat-treated at 700–1000°C (e.g., 800°C or 900°C) for 10–120 minutes (e.g., 30 minutes, 60 minutes, or 90 minutes), followed by annealing at 850°C for 1.5 hours and air cooling. The cooled glass is then polished to a glossy finish using 120#–2500# sandpaper.

[0084] The titanium alloy cold-rolled sheet obtained by the method of suppressing edge cracks in the titanium alloy rolling process provided by the present invention has good microstructure uniformity, reduces internal structural defects, obtains fine grain size, and improves the strength and hardness of the titanium alloy cold-rolled sheet, as well as the overall toughness of the titanium alloy cold-rolled sheet.

[0085] The method for suppressing edge cracks during the rolling process of titanium alloys provided by this invention can be used to cold roll titanium alloys to obtain crack-free cold-rolled titanium alloy sheets. This helps to reduce the scrap rate and rework rate of titanium alloy sheets, lower production costs, broaden the processing and application potential of titanium alloys, and enrich the application scenarios of titanium alloys.

[0086] Secondly, the present invention provides a method for preparing titanium alloy rolled parts, including the method for suppressing edge cracks generated during the titanium alloy rolling process.

[0087] The method for suppressing edge cracks during the rolling process of titanium alloys and the method for preparing titanium alloy rolled parts provided by this invention are simple and convenient. The titanium alloy plates prepared by the edge constraint method are crack-free and have excellent surface quality, which can meet the urgent needs of various fields for high-performance titanium materials and provide a new direction for the preparation of high-performance titanium materials.

[0088] In some specific embodiments, the preparation method of the titanium alloy sheet includes: hot rolling a thick titanium alloy plate. Hot rolling can achieve the thinning of the thick titanium alloy plate and the titanium alloy sheet.

[0089] In some specific embodiments, the heating temperature for hot rolling is 900–1040°C, for example, 900°C, 930°C, 950°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, or 1030°C, and the holding time is 0.1–20 hours, for example, 1 hour, 3 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 15 hours, or 18 hours. That is, the titanium alloy thick plate is heated to an initial rolling temperature of 900–1040°C and held for 0.1–20 hours, followed by multiple passes of hot rolling and reversing hot rolling.

[0090] In some specific embodiments, the hot rolling speed is 0.1 to 5 m / s; including but not limited to any one of 0.5 m / s, 1 m / s, 1.5 m / s, 2 m / s, 2.5 m / s, 3 m / s, 3.5 m / s, 4 m / s, 4.5 m / s, 5 m / s or any range between two of them.

[0091] In some specific embodiments, the rolling reduction per pass of the hot rolling is 10% to 12%; including but not limited to any one of 10%, 1.5%, 11%, 11.5%, 12% or any range between two.

[0092] In some specific embodiments, the number of rolling passes in the hot rolling process is 5 to 30, for example, 6, 7, 8, 10, 15, 20 or 25.

[0093] By controlling the above hot rolling parameters, the processing performance of titanium alloys can be improved, the properties of titanium alloys can be enhanced, production efficiency can be increased, energy consumption can be reduced, roll wear can be reduced, and the operating rate can be increased.

[0094] In some specific embodiments, a high-temperature antioxidant is coated onto the titanium alloy thick plate before hot rolling. The high-temperature antioxidant includes, but is not limited to, any reagent commonly used in the art, such as high-temperature glass protectants SA-35, FR35, GDS-17, GHJD, etc.

[0095] In some specific embodiments, after hot rolling, there are also steps of cutting, pickling, and sandblasting.

[0096] That is, after hot rolling and cooling, the thin plate is cut to remove the oxygen-rich layer on the edge, pickled to remove the oxide scale and other impurities on the surface, sandblasted, cleaned and dried to obtain a titanium alloy plate with good shape.

[0097] Thirdly, the present invention provides the application of the method for suppressing edge cracks during the rolling process of titanium alloys or the method for preparing titanium alloy rolled parts in the preparation of titanium alloy products.

[0098] Titanium alloy products prepared by the above-mentioned methods for suppressing edge cracks during the rolling process of titanium alloys or by the preparation methods of titanium alloy rolled parts have good quality, uniform and fine grain structure, excellent mechanical properties, and low production cost.

[0099] Among them, titanium alloy products include any parts, components, and parts containing titanium alloys, and their application fields include but are not limited to marine engineering, aerospace, and medical fields. This invention does not limit these fields.

[0100] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0101] Example 1

[0102] The method for suppressing edge cracks during the cold rolling process of TC4 titanium alloy provided in this embodiment is also a method for preparing TC4 titanium alloy rolled parts, and includes the following steps:

[0103] (1) Take a TC4 titanium alloy thick plate with a thickness of 100 mm, a weight of 470 kg, and a β transformation point of 995 °C. Apply a high-temperature glass protective agent SA-35 evenly to the TC4 titanium alloy thick plate, heat it at 980 °C and hold it for 5 hours; then perform 6 passes of hot rolling and 3 passes of reversing rolling, with a reduction of 10% per pass and a rolling speed of 3 m / s, until the TC4 titanium alloy thick plate is thinned to 40 mm. Then, remove the oxygen-rich layer at the edges of the cooled TC4 titanium alloy hot-rolled plate by cutting, and obtain a TC4 titanium alloy sheet with a good plate shape by pickling and sandblasting.

[0104] (2) The surface of the TC4 titanium alloy sheet obtained in step (1) is uniformly coated with a special high-temperature glass protective agent SA-35 for titanium alloys to prevent oxidation. After the high-temperature glass protective agent solidifies, it is placed in a furnace and heat-treated at 920°C for 10 minutes, followed by annealing at 850°C for 1.5 hours and air-cooling. Then, the sheet is polished to a bright finish using 1000# sandpaper after being air-cooled to room temperature.

[0105] (3) The titanium alloy sheet obtained in step (2) is placed in the first U-shaped fixture for edge constraint, wherein the titanium alloy sheet and the first U-shaped fixture are interference fit by external force, and the first U-shaped fixture covers the titanium alloy sheet. Then, a large reduction cold rolling is performed, wherein the reduction of each rolling pass is 10%, the rolling passes are 5, the total rolling reduction is 50%, the rolling speed is 1.5m / s, and titanium and titanium alloy foil cold rolling lubricant is used in each rolling process. After rolling, the broken first U-shaped fixture is removed to obtain a crack-free TC4 titanium alloy initial rolled sheet.

[0106] (4) The initial rolled sheet obtained in step (3) is placed in the second U-shaped fixture for edge constraint. The initial rolled sheet and the second U-shaped fixture are interference-fitted by external force, and the second U-shaped fixture covers the initial rolled sheet. Then, a small reduction is performed for cold rolling. The reduction of each rolling pass is 5%, and the total reduction after the second edge constraint is 10%. The rolling speed is 0.5 m / s. Titanium and titanium alloy foil cold rolling lubricant are used in each rolling process. After rolling, the second U-shaped fixture is removed to obtain a crack-free TC4 titanium alloy cold rolled sheet.

[0107] In steps (3) and (4), the cross-sectional shape of the first U-shaped fixture and the second U-shaped fixture is U-shaped. The height of the first U-shaped fixture is equal to the height of the titanium alloy plate, and the height of the second U-shaped fixture is equal to the height of the plate after initial rolling. The dimensions of the bottom surface and two sides of the first U-shaped fixture match the dimensions of the titanium alloy plate, and the dimensions of the bottom surface and two sides of the second U-shaped fixture match the dimensions of the plate after initial rolling.

[0108] (5) The TC4 titanium alloy cold-rolled sheet obtained in step (4) is annealed at 700°C for 30 minutes, then sandblasted to remove the rolling lubricant on the surface, and then cleaned and dried to obtain a crack-free, high-performance TC4 titanium alloy rolled piece.

[0109] Example 2

[0110] The method for suppressing edge cracks during the cold rolling of TC4 titanium alloy and the method for preparing TC4 titanium alloy rolled pieces provided in this embodiment are basically the same as those in Example 1. The difference is that in step (1), after applying a high-temperature anti-oxidant, the plate is heated at 1040°C and held for 4 hours; through 6 passes of hot rolling and 3 passes of reversing rolling, the rolling reduction in each pass is 12%, and the rolling speed is 5m / s, until the TC4 titanium alloy thick plate is thinned to 40mm.

[0111] Example 3

[0112] The method for suppressing edge cracks during the cold rolling of TC4 titanium alloy and the method for preparing TC4 titanium alloy rolled pieces provided in this embodiment are basically the same as those in Embodiment 1. The difference is that in step (2), heat treatment is performed at 920°C for 20 min, followed by annealing at 850°C for 1.5 h and air cooling.

[0113] Example 4

[0114] The method for suppressing edge cracks during the cold rolling of TC4 titanium alloy and the method for preparing TC4 titanium alloy rolled pieces provided in this embodiment are basically the same as those in Example 1. The difference is that in step (3), during the large reduction cold rolling process, the rolling reduction per pass is 12%, the rolling passes are 5, the total rolling reduction is 60%, and the rolling speed is 2m / s.

[0115] Example 5

[0116] The method for suppressing edge cracks during the cold rolling of TC4 titanium alloy and the method for preparing TC4 titanium alloy rolled pieces provided in this embodiment are basically the same as those in Example 1. The difference is that in step (4), during the cold rolling process with small reduction, the reduction per pass is 6%, the number of rolling passes is 5, the total reduction after the second edge constraint is 20%, and the rolling speed is 1m / s.

[0117] Example 6

[0118] The method for suppressing edge cracks during the cold rolling of TC4 titanium alloy and the method for preparing TC4 titanium alloy rolled pieces provided in this embodiment are basically the same as those in Embodiment 1. The difference is that in step (1), the TC4 titanium alloy thick plate is replaced with a Ti80 titanium alloy thick plate of equal thickness and weight.

[0119] Comparative Example 1

[0120] The preparation method of the TC4 titanium alloy rolled piece provided in this comparative example is basically the same as that in Example 1. The difference is that the first U-shaped fixture is not used in step (3) and the second U-shaped fixture is not used in step (4). Instead, the titanium alloy plate and the plate after the initial rolling are directly cold rolled.

[0121] This comparative example did not use a U-shaped clamp. During the cold rolling process of TC4 titanium alloy sheet, some fine cracks were generated during large-reduction cold rolling. These cracks gradually expanded as the rolling reduction increased. After two cold rolling cycles, a large number of edge cracks appeared in the TC4 titanium alloy cold-rolled sheet.

[0122] Figure 3 This is an image of the titanium alloy rolled product obtained in Example 1. Figure 4 This is an image of the titanium alloy rolled product obtained in Comparative Example 1. By comparison... Figure 3 and Figure 4It can be seen that the TC4 cold-rolled sheet produced in Comparative Example 1 without the use of a U-shaped clamp developed edge cracks (see...). Figure 4 In contrast, the TC4 cold-rolled sheet produced using a U-shaped clamp in Example 1 showed no edge cracks (see Example 1). Figure 3 ).

[0123] Comparative Example 2

[0124] The preparation method of the TC4 titanium alloy rolled piece provided in this comparative example is basically the same as that in Example 1. The difference is that in step (4), the rolling reduction of each pass of the small reduction cold rolling is 10%, the rolling passes are 3, and the total reduction after the second edge constraint is 30%.

[0125] Figure 5 This is an image of the titanium alloy rolled product obtained in Comparative Example 2. By comparison... Figure 3 and Figure 5 It can be seen that in Example 1, when using the second U-shaped fixture to perform a second cold rolling of TC4 titanium alloy sheet, a low rolling reduction of 5% per pass was adopted. During the second edge-constrained cold rolling process, no cracks were generated in the TC4 titanium alloy cold-rolled sheet. However, in Comparative Example 2, which used a rolling reduction of 10% per pass and controlled the total rolling reduction to 30%, cracks still occurred. This shows that the present invention can effectively suppress the generation of edge cracks by controlling the rolling reduction per pass of small-reduction cold rolling.

[0126] Furthermore, the mechanical properties of the TC4 titanium alloy rolled pieces prepared in each embodiment and each comparative example were tested, and the results are shown in Table 1.

[0127] Table 1. Test results of mechanical properties of various TC4 titanium alloy rolled products

[0128] Group Yield strength (MPa) Tensile strength (MPa) Hardness (HV) Elongation (%) Example 1 921.4 1024.4 300.5 13.2 Example 2 889.2 980.5 342.4 11.1 Example 3 887.4 978.4 356.2 10.8 Example 4 907.4 1010.3 344.1 10.5 Example 5 894.6 998.9 342.3 9.9 Example 6 904.7 1012.3 344.5 9.8 Comparative Example 1 915.1 1025.1 352.4 7.0 Comparative Example 2 900.4 1008.4 355.8 9.4

[0129] As shown in Table 1, the mechanical properties of the TC4 titanium alloy rolled products obtained in each embodiment are significantly better than those in the comparative examples. This indicates that the present invention can improve the mechanical properties of TC4 titanium alloy rolled products by optimizing rolling parameters.

[0130] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for suppressing edge cracks during the rolling process of titanium alloys, characterized in that, Includes the following steps: A titanium alloy sheet is placed in a first U-shaped fixture for edge constraint, wherein the titanium alloy sheet and the first U-shaped fixture are interference-fitted and the first U-shaped fixture covers the titanium alloy sheet. Then, a large reduction cold rolling is performed, wherein the reduction in each pass of the large reduction cold rolling is 5% to 12%, and the total reduction in the large reduction cold rolling is 50% to 60%. After that, the broken first U-shaped fixture is removed to obtain the sheet after initial rolling. The pre-rolled sheet is placed in a second U-shaped fixture for edge constraint, wherein the pre-rolled sheet and the second U-shaped fixture are interference-fitted and the second U-shaped fixture covers the pre-rolled sheet. Then, it is cold-rolled with a small reduction, and then the second U-shaped fixture is removed to obtain a titanium alloy cold-rolled sheet. Wherein, the cross-sectional shape of both the first U-shaped clamp and the second U-shaped clamp is U-shaped; The reduction per pass in the small reduction cold rolling is 2% to 5%, and the total reduction in the small reduction cold rolling is 10% to 20%.

2. The method for suppressing edge cracks during the rolling process of titanium alloys according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The height of the first U-shaped clamp is equal to the height of the titanium alloy plate; (2) The height of the second U-shaped clamp is equal to the height of the plate after initial rolling; (3) The dimensions of the bottom surface and two sides of the first U-shaped clamp are matched with the dimensions of the titanium alloy plate; (4) The dimensions of the bottom surface and two sides of the second U-shaped fixture are matched with the dimensions of the pre-rolled plate.

3. The method for suppressing edge cracks during the rolling process of titanium alloys according to claim 1, characterized in that, The titanium alloy sheet includes at least one of TC4 titanium alloy sheet and Ti80 titanium alloy sheet.

4. The method for suppressing edge cracks during the rolling process of titanium alloys according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The rolling speed of the large reduction cold rolling is 0.01~2m / s; (2) Rolling lubricant is used in each rolling process of the large reduction cold rolling.

5. The method for suppressing edge cracks during the rolling process of titanium alloys according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The rolling speed of the small reduction cold rolling is 0.01~2m / s; (2) Rolling lubricant is used in each rolling pass of the small reduction cold rolling process.

6. The method for suppressing edge cracks during the rolling process of titanium alloys according to claim 1, characterized in that, Before placing the titanium alloy sheet in the first U-shaped fixture, the titanium alloy sheet undergoes a homogenization treatment. The homogenization treatment method includes: coating a high-temperature glass protective agent onto a titanium alloy plate, and after the high-temperature glass protective agent solidifies, heat-treating it at 700~1000℃ for 10~120 min, followed by annealing at 850℃ for 1.5 h, and air cooling.

7. A method for preparing titanium alloy rolled parts, characterized in that, Including the method for suppressing edge cracks generated during the rolling process of titanium alloys as described in any one of claims 1 to 6.

8. The method for preparing titanium alloy rolled parts according to claim 7, characterized in that, The method for preparing the titanium alloy plate includes: hot rolling a thick titanium alloy plate; The hot rolling meets at least one of the following conditions: (1) the heating temperature of the hot rolling is 900~1040℃ and the holding time is 0.1~20h; (2) the rolling speed of the hot rolling is 0.1~5m / s; (3) the rolling reduction per pass of the hot rolling is 10%~12%; (4) the number of rolling passes of the hot rolling is 5~30.

9. The method for preparing titanium alloy rolled parts according to claim 8, characterized in that, Prior to the hot rolling, a high-temperature anti-oxidant is coated onto the titanium alloy thick plate; And / or, after hot rolling, the process may include cutting, pickling and sandblasting steps.

10. The method for suppressing edge cracks during the rolling process of titanium alloys as described in any one of claims 1 to 6, or the method for preparing titanium alloy rolled parts as described in any one of claims 7 to 9, is used in the preparation of titanium alloy products.

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