Rolling method for inhibiting generation of edge cracks in titanium alloy rolling process

Abstract

The invention relates to the technical field of titanium alloy machining, in particular to a rolling method for inhibiting edge cracks generated in the titanium alloy rolling process. The method for inhibiting the edge cracks generated in the titanium alloy rolling process comprises the steps that a titanium alloy plate is placed in a first U-shaped clamp to be in interference fit, then large-rolling-reduction cold rolling is conducted, then the first U-shaped clamp is removed, and a primarily-rolled plate is obtained; the plate obtained after primary rolling is placed in a second U-shaped clamp to be in interference fit, then small-rolling-reduction cold rolling is conducted, the second U-shaped clamp is removed, and the titanium alloy cold-rolled plate is obtained; the rolling reduction of each pass of the small rolling reduction cold rolling is 2%-5%, and the total rolling reduction of the small rolling reduction cold rolling is 10%-20%. According to the method, the clamp is adopted for carrying out edge constraint on the titanium alloy plate to be cold-rolled, and edge cracks in the titanium alloy cold rolling process can be effectively restrained; and the rolling reduction of each pass and the total rolling reduction of small rolling reduction cold rolling are controlled, so that the generation of edge cracks can be further inhibited.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy processing. Specifically, it relates to a rolling method for suppressing edge cracks during the rolling process of titanium alloys. Background Art

[0002] Due to its excellent properties of light weight, high strength, high temperature resistance and corrosion resistance, titanium alloys are widely used in the fields of aviation, aerospace, automobiles, ships, etc. Cold rolling of titanium alloys is a processing method that changes the shape and size of metals by applying pressure under conditions below the metal recrystallization temperature. As an important metal processing method, cold rolling has the advantages of improving material strength, improving surface quality, and achieving complex shapes. This process is an important means to realize the plastic deformation of titanium alloy sheets and manufacture 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 affected. In addition, cold rolling processing plays an important role in improving the strength and hardness of titanium alloys and improving the plasticity of materials.

[0003] However, when cold rolling titanium alloys, edge cracking is a common defect that needs to be focused on. During the cold rolling process, titanium alloys are rolled between two or more rolls in a rolling mill. The gap between the rolls gradually decreases, so that the thickness of the material also gradually decreases. Titanium alloy sheets will undergo different degrees of strain hardening during rolling, resulting in a decrease in the toughness of the material. Especially obvious edge cracking will occur in the thinner edge part. The increase in the rolling speed will lead to an increase in the deformation rate of the material, and too high a speed may lead to local stress concentration and increase the risk of edge cracking. In addition, due to uneven contact of the rolls or uneven initial state of the material, the stress borne by the edge area may be too large, thus causing cracks.

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

[0005] The first object of the present invention is to provide a method for suppressing edge cracks during the rolling process of titanium alloys. By using a fixture to perform edge restraint on the titanium alloy sheet to be cold rolled, it can effectively suppress the generation of edge cracks during the cold rolling process of titanium alloys, thereby improving the overall quality of cold-rolled titanium alloy sheets. It solves the problem that the existing cold rolling technology causes edge cracking in titanium alloys. At the same time, the present invention can further suppress the generation of edge cracks by controlling the rolling reduction per pass and the total rolling reduction of cold rolling with a small reduction.

[0006] The second object of the present invention is to provide a method for preparing titanium alloy rolled pieces.

[0007] The third object of the present invention is to provide the application of the method for suppressing edge cracks during the rolling process of titanium alloys or the method for preparing titanium alloy rolled pieces in the preparation of titanium alloy products.

[0008] To achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0009] The present invention first provides a method for suppressing edge cracks generated during the rolling process of titanium alloys, including 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 in interference fit, and the first U-shaped fixture covers the titanium alloy sheet, then performing cold rolling with a large reduction ratio, and then removing the first U-shaped fixture to obtain a preliminarily rolled sheet; placing the preliminarily rolled sheet in a second U-shaped fixture for edge restraint, wherein the preliminarily rolled sheet and the second U-shaped fixture are in interference fit, and the second U-shaped fixture covers the preliminarily rolled sheet, then performing cold rolling with a small reduction ratio, and then removing the second U-shaped fixture to obtain a cold-rolled titanium alloy sheet; wherein, the cross-sectional shapes of the first U-shaped fixture and the second U-shaped fixture are both U-shaped; the reduction ratio per pass of the cold rolling with a small reduction ratio is 2% - 5%, and the total reduction ratio of the cold rolling with a small reduction ratio is 10% - 20%.

[0010] Further, the height of the first U-shaped fixture is equal to the height of the titanium alloy sheet.

[0011] Further, the height of the second U-shaped fixture is equal to the height of the preliminarily rolled sheet.

[0012] Further, the dimensions of the bottom surface and the two side surfaces of the first U-shaped fixture are matched with the dimensions of the titanium alloy sheet.

[0013] Further, the dimensions of the bottom surface and the two side surfaces of the second U-shaped fixture are matched with the dimensions of the preliminarily rolled sheet.

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

[0015] Further, the reduction ratio per pass of the cold rolling with a large reduction ratio is 5% - 12%.

[0016] Further, the rolling rate of the cold rolling with a large reduction ratio is 0.01 - 2 m / s.

[0017] Further, the total reduction ratio of the cold rolling with a large reduction ratio is 20% - 60%.

[0018] Further, a rolling lubricant is used during each pass of the cold rolling with a large reduction ratio.

[0019] Further, the reduction ratio per pass of the cold rolling with a small reduction ratio is 2% - 5%.

[0020] Further, the rolling rate of the cold rolling with small reduction is 0.01 - 2 m / s.

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

[0022] Further, rolling lubricant is used in each pass of the cold rolling with small reduction.

[0023] Further, before placing the titanium alloy sheet in the first U-shaped fixture, the titanium alloy sheet is subjected to homogenization treatment.

[0024] Further, the method of the homogenization treatment includes: coating a high-temperature glass protective agent on the titanium alloy sheet, and after the high-temperature glass protective agent condenses, performing heat treatment at 700 - 1000 °C for 10 - 120 min, then annealing at 850 °C for 1.5 h, and air cooling.

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

[0026] Further, the method for preparing the titanium alloy sheet includes: hot rolling a titanium alloy wide and thick plate.

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

[0028] Further, the rolling speed of the hot rolling is 0.1 - 5 m / s.

[0029] Further, the rolling reduction per pass of the hot rolling is 10% - 12%.

[0030] Further, the number of rolling passes of the hot rolling is 5 - 30 times.

[0031] Further, before the hot rolling, a high-temperature antioxidant is coated on the titanium alloy wide and thick plate.

[0032] Further, after the hot rolling, it further includes the steps of cutting, pickling, and sandblasting.

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

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

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

[0036] (2) The method provided by the present invention for suppressing edge cracks during the rolling process of titanium alloys can further reduce the risk of plate cracking and effectively improve the plastic deformation ability of titanium alloy plates, obtain a uniform and refined grain structure, and obtain excellent mechanical properties by optimizing the rolling parameters to control the degree of material deformation.

[0037] (3) The cold-rolled titanium alloy plates obtained by using the method provided by the present invention for suppressing edge cracks during the rolling process of titanium alloys have good microstructural uniformity, reduce the internal tissue defects of the material, obtain a fine grain size, and improve the strength and hardness of the cold-rolled titanium alloy plates, and improve the overall toughness of the cold-rolled titanium alloy plates.

[0038] (4) By using the method provided by the present invention for suppressing edge cracks during the rolling process of titanium alloys to carry out cold rolling of titanium alloys, crack-free cold-rolled titanium alloy plates can be obtained, which helps to reduce the scrap rate and rework rate of titanium alloy plates and reduce the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1 It is a schematic structural diagram of the first U-shaped fixture and the second U-shaped fixture provided by the present invention;

[0041] Figure 2 It is a cross-sectional schematic diagram of the first U-shaped fixture and the second U-shaped fixture provided by the present invention;

[0042] Figure 3 It is a picture of the titanium alloy rolled piece obtained in Example 1 provided by the present invention;

[0043] Figure 4 It is a picture of the titanium alloy rolled piece obtained in Comparative Example 1 provided by the present invention;

[0044] Figure 5 A picture of the titanium alloy rolled product obtained in Comparative Example 2 provided by the present invention. Detailed implementation manners

[0045] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and detailed implementation manners. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0046] If there is no special description, in the present invention, "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "the first", "the second", "the third", "the fourth", etc. only serve the purpose of non-exhaustive enumerative description and should be understood not to constitute a closed limitation on the quantity.

[0047] If there is no special description, "including" and "comprising" mentioned in the present invention mean open-ended, and can also be closed-ended. For example, the said "including" and "comprising" can mean that other components not listed can also be included or comprised, or can only include or comprise the listed components.

[0048] If there is no special description, in the present invention, "one or more" or "at least one" refers to any one, any two or any two or more of the listed items. Among them, "several" refers to any two or any two or more.

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

[0050] Place the titanium alloy sheet in the first U-shaped fixture for edge constraint, wherein the titanium alloy sheet and the first U-shaped fixture are in interference fit, and the first U-shaped fixture covers the titanium alloy sheet, and then perform cold rolling with a large reduction, and then remove the broken first U-shaped fixture to obtain the sheet after primary rolling. That is, the inner diameter size of the first U-shaped fixture and the size of the titanium alloy sheet are in interference fit. And on each contact surface where the first U-shaped fixture contacts the titanium alloy sheet, the first U-shaped fixture covers the titanium alloy sheet.

[0051] Place the rolled plate after primary rolling in the second U-shaped fixture for edge constraint. The rolled plate after primary rolling and the second U-shaped fixture are in interference fit, and the second U-shaped fixture covers the rolled plate after primary rolling. Then, cold rolling is performed with a small reduction, and then the second U-shaped fixture is removed to obtain a cold-rolled titanium alloy plate. That is, the inner diameter dimension of the second U-shaped fixture and the dimension of the rolled plate after primary rolling are in interference fit. And on each contact surface where the second U-shaped fixture contacts the rolled plate after primary rolling, the second U-shaped fixture covers the titanium alloy plate.

[0052] Among them, the cross-sectional shapes of the first U-shaped fixture and the second U-shaped fixture are both U-shaped. The first U-shaped fixture and the second U-shaped fixture are collectively referred to as the fixture. It can be understood that the fixture has a bottom surface and side surfaces respectively connected to both ends of the bottom surface. The bottom surface and the two side surfaces enclose a rectangular parallelepiped-shaped (or plate-shaped) accommodation space for accommodating the titanium alloy plate or the rolled plate after primary rolling to be cold-rolled.

[0053] Among them, the U-shaped fixture will not adhere to the plate during cold rolling. If it is fully covered, on the one hand, interference fit cannot be achieved, and on the other hand, metal adhesion is likely to occur.

[0054] As Figure 1 shown is the three-dimensional structure schematic diagram of the first U-shaped fixture and the second U-shaped fixture.

[0055] As Figure 2 shown is the cross-sectional schematic diagram of the first U-shaped fixture and the second U-shaped fixture.

[0056] See Figure 2 shown. The fixture and the titanium alloy plate or the rolled plate after primary rolling to be cold-rolled adopt an interference fit method in the RD×TD direction (that is, the fixture and the titanium alloy plate or the rolled plate after primary rolling adopt an interference fit method on the rolling side). During the interference fit process, the titanium alloy plate or the rolled plate after primary rolling to be cold-rolled is combined with the fixture using an external force. During the combination process, the fixture may undergo slight deformation due to its structural reasons, enabling the titanium alloy plate or the rolled plate after primary rolling to be cold-rolled to achieve an interference fit with the fixture.

[0057] The method for suppressing edge cracks during titanium alloy rolling provided by the present invention, by setting the first U-shaped fixture and the second U-shaped fixture (collectively referred to as the fixture), during cold rolling, the fixture and the titanium alloy plate or the rolled plate after primary rolling are simultaneously cold-rolled and deformed. This interference fit edge constraint method can effectively transfer the rolling stress to the fixture during cold rolling, protecting the edges of the titanium alloy rolled piece. By presetting the edge cracks that occur in the original titanium alloy plate or the rolled plate after primary rolling during cold rolling onto the fixture, protective rolling of the titanium alloy plate is achieved, effectively suppressing the generation of cracks during titanium alloy cold rolling.

[0058] Meanwhile, when the U-shaped fixture is used for the first time in the present invention, it is combined with a cold rolling regime of large reduction per pass, and then the U-shaped fixture is replaced. When the U-shaped fixture is used for the second time and combined with a cold rolling regime of small reduction per pass, it can effectively improve and enhance the plastic deformation ability of titanium alloy sheets, obtain a uniform and refined grain structure, avoid the phenomenon of edge cracks caused by stress concentration during cold rolling, and obtain cold-rolled titanium materials with excellent mechanical properties.

[0059] The reduction per pass of the cold rolling with small reduction per pass is 2% - 5%, including but not limited to the point values of any one of 2%, 3%, 4%, 5%, 6% or the range values between any two of them; the total reduction of the cold rolling with small reduction per pass is 10% - 20%, such as 13%, 15% or 18%. By controlling the reduction per pass and the total reduction of the cold rolling with small reduction per pass, the present invention can further inhibit the generation of edge cracks.

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

[0061] In some specific embodiments, the height of the second U-shaped fixture (inner diameter height, or the height of the accommodating space) is equal to the height of the sheet after primary rolling.

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

[0063] In some specific embodiments, the dimensions of the bottom surface and the two side surfaces of the second U-shaped fixture are matched with the dimensions of the sheet after primary rolling. That is, the bottom surface of the second U-shaped fixture completely covers the bottom surface of the sheet after primary rolling in contact with it, and the two side surfaces of the second U-shaped fixture completely cover the side surfaces of the sheet after primary rolling in contact with it.

[0064] During cold rolling, edge cracks will appear on the fixture, thereby inhibiting the generation of cracks in the edge-constrained titanium alloy sheet. The dimensions of the fixture are matched with the dimensions of the titanium alloy sheet or the sheet after primary rolling, which can effectively inhibit edge cracks.

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

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

[0067] The occurrence of edge cracking is usually closely related to parameters such as the rolling reduction and rolling rate. Changes in these parameters will directly affect the stress state, deformation behavior of the material, and the final processing quality. To reduce the occurrence of edge cracking during cold rolling, the present invention controls the degree of deformation of the material by optimizing rolling deformation parameters such as the reduction per pass, rolling rate, and total rolling reduction, thereby reducing the risk of sheet cracking.

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

[0069] In some specific embodiments, the rolling rate of the cold rolling with large reduction is 0.01 - 2 m / s; including but not limited to the point values of 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, 2 m / s or the range values between any two of them. Here, the unit m / s is meters per second.

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

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

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

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

[0074] In some specific embodiments, the rolling rate of the cold rolling with small reduction is 0.01 - 2 m / s; including but not limited to the point values of 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, 2 m / s or the range values between any two of them.

[0075] By controlling the rolling rate during the cold rolling process, the present invention can further reduce the risk of edge cracking.

[0076] When the rolling reduction is large, although it can promote the fragmentation of grains, refine the structure, and enhance the mechanical properties of the rolled piece, due to incomplete grain fragmentation during the rolling process of titanium alloy, it may lead to internal stress concentration and increase the risk of edge crack formation. By setting fixtures to perform edge constraint on the sheet to be cold rolled and controlling the rolling reduction per pass and the total rolling reduction during the cold rolling process, the present invention can effectively reduce the risk of edge crack formation.

[0077] Moreover, when using the first U-shaped fixture for the present invention, it is used in conjunction with multiple passes and large reduction until the total reduction reaches 20% - 60%, and then the second U-shaped fixture is replaced. When using the second U-shaped fixture, it is used in conjunction with the cold rolling system of multiple passes and small reduction until the total rolling reduction of the two times reaches 80% - 90%. This cold rolling system can effectively improve and enhance the plastic deformation ability of titanium alloy sheets, obtain a uniform and refined grain structure, avoid the phenomenon of edge cracks caused by stress concentration during cold rolling, and obtain cold-rolled titanium materials with excellent mechanical properties.

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

[0079] Among them, the rolling lubricant includes any reagent commonly used in the art, such as cold rolling lubricant for titanium and titanium alloy foils, etc., but not limited thereto.

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

[0081] In some specific embodiments, before placing the titanium alloy sheet in the first U-shaped fixture, the titanium alloy sheet is subjected to homogenization treatment to homogenize the structure. Among them, the homogenization treatment can improve the structure and properties of the titanium alloy and provide a better material state for subsequent cold rolling.

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

[0083] After the high-temperature glass protective agent condenses, put it into the furnace and perform heat treatment at 700-1000 °C (such as 800 °C or 900 °C) for 10-120 min (such as 30 min, 60 min or 90 min), then anneal at 850 °C for 1.5 h and air-cool. Subsequently, use sandpaper with 120#-2500# to polish the sheet air-cooled to room temperature until it is bright.

[0084] The titanium alloy cold-rolled sheet obtained by using the method for suppressing edge cracks during titanium alloy rolling provided by the present invention has good microstructural uniformity, reduces the internal tissue defects of the material, obtains a fine grain size, and improves the strength and hardness of the titanium alloy cold-rolled sheet, and improves the overall toughness of the titanium alloy cold-rolled sheet.

[0085] By using the method for suppressing edge cracks during titanium alloy rolling provided by the present invention to perform cold rolling of titanium alloy, a crack-free titanium alloy cold-rolled sheet can be obtained, which helps to reduce the rejection rate and rework rate of titanium alloy sheets, reduce production costs, broaden the processing and application potential of titanium alloy, and enrich the application scenarios of titanium alloy.

[0086] In the second aspect, the present invention provides a method for preparing a titanium alloy rolled piece, including the method for suppressing edge cracks during titanium alloy rolling.

[0087] The method for suppressing edge cracks during titanium alloy rolling and the method for preparing a titanium alloy rolled piece provided by the present invention are simple and convenient. The titanium alloy sheet obtained by the edge constraint method has no cracks and excellent surface quality, can meet the urgent needs of various fields for high-performance titanium materials, and provides a new direction for the preparation of high-performance titanium materials.

[0088] In some specific embodiments, the method for preparing the titanium alloy sheet includes: hot rolling the titanium alloy wide and thick plate. By hot rolling, the thickness reduction of the titanium alloy wide and thick plate and the titanium alloy sheet can be achieved.

[0089] In some specific embodiments, the heating temperature of the hot rolling is 900 - 1040 °C, such as 900 °C, 930 °C, 950 °C, 980 °C, 990 °C, 1000 °C, 1010 °C, 1020 °C or 1030 °C, and the heat preservation time is 0.1 - 20 h, such as 1 h, 3 h, 5 h, 6 h, 8 h, 10 h, 12 h, 15 h or 18 h. That is, the titanium alloy wide and thick plate is heated to the initial rolling temperature of 900 - 1040 °C, and heat-preserved for 0.1 - 20 h, then multi-pass hot rolling and reverse hot rolling are carried out.

[0090] In some specific embodiments, the rolling speed of the hot rolling is 0.1 - 5 m / s; including but not limited to the point value of 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 the range value between any two of them.

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

[0092] In some specific embodiments, the number of rolling passes of the hot rolling is 5 - 30 times, such as 6 times, 7 times, 8 times, 10 times, 15 times, 20 times or 25 times.

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

[0094] In some specific embodiments, before the hot rolling, a high-temperature anti-oxidant is coated on the titanium alloy wide and thick plate. Among them, the high-temperature anti-oxidant includes any reagent commonly used in the art, such as high-temperature glass protective agents SA-35, FR35, GDS-17, GHJD, etc., but not limited thereto.

[0095] In some specific embodiments, after the hot rolling, it further includes the steps of cutting, pickling and sandblasting.

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

[0097] In the third aspect, the present invention provides the application of the method for suppressing edge cracks generated during the rolling of titanium alloy or the preparation method of the titanium alloy rolled piece in the preparation of titanium alloy products.

[0098] The titanium alloy product prepared by the method for suppressing edge cracks during titanium alloy rolling or the preparation method of the titanium alloy rolled piece has good quality, with a uniform and refined grain structure, excellent mechanical properties, and low production cost.

[0099] Among them, the titanium alloy product includes any workpiece, part, component, etc. containing titanium alloy, and the application fields include but are not limited to marine engineering, aerospace field, medical field, etc. The present invention does not make any limitation in this regard.

[0100] The embodiments of the present invention will be described in detail below. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0101] Example 1

[0102] The method for suppressing edge cracks during the cold rolling of TC4 titanium alloy provided in this example is also the preparation method of TC4 titanium alloy rolled piece, and includes the following steps:

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

[0104] (2) Uniformly coat the surface of the TC4 titanium alloy plate obtained in step (1) with the special high-temperature glass protective agent SA-35 for titanium alloy to prevent oxidation. After the high-temperature glass protective agent condenses, put it into the furnace, perform heat treatment at 920 °C for 10 min, then anneal at 850 °C for 1.5 h, and air-cool. Subsequently, use 1000# sandpaper to polish the plate air-cooled to room temperature until it is bright.

[0105] (3) Place the titanium alloy sheet obtained in step (2) in the first U-shaped fixture for edge constraint. The titanium alloy sheet and the first U-shaped fixture are in interference fit through an external force, and the first U-shaped fixture covers the titanium alloy sheet. Then, cold rolling with a large reduction is carried out. The reduction per pass is 10%, the number of rolling passes is 5, the total rolling reduction is 50%, the rolling rate is 1.5 m / s, and the cold rolling lubricant for titanium and titanium alloy foils is used during each pass of rolling. After rolling is completed, remove the fractured first U-shaped fixture to obtain a crack-free TC4 titanium alloy primary rolling sheet.

[0106] (4) Place the sheet after primary rolling obtained in step (3) in the second U-shaped fixture for edge constraint. The sheet after primary rolling and the second U-shaped fixture are in interference fit through an external force, and the second U-shaped fixture covers the sheet after primary rolling. Then, cold rolling with a small reduction is carried out. The reduction per pass is 5%, the total reduction after the second edge constraint is 10%, the rolling rate is 0.5 m / s, and the cold rolling lubricant for titanium and titanium alloy foils is used during each pass of rolling. After rolling is completed, remove the second U-shaped fixture to obtain a crack-free TC4 titanium alloy cold-rolled sheet.

[0107] In steps (3) and (4), the cross-sectional shapes of the first U-shaped fixture and the second U-shaped fixture are both U-shaped. The height of the first U-shaped fixture is equal to the height of the titanium alloy sheet, the height of the second U-shaped fixture is equal to the height of the sheet after primary rolling, the dimensions of the bottom surface and the two side surfaces of the first U-shaped fixture match the dimensions of the titanium alloy sheet, and the dimensions of the bottom surface and the two side surfaces of the second U-shaped fixture match the dimensions of the sheet after primary rolling.

[0108] (5) Anneal the TC4 titanium alloy cold-rolled sheet obtained in step (4) at 700 °C for 30 min, then carry out sandblasting to remove the rolling lubricant on the surface, and perform cleaning and drying to obtain a crack-free and high-performance TC4 titanium alloy rolled piece.

[0109] Example 2

[0110] The method for suppressing edge cracks during cold rolling of TC4 titanium alloy and the preparation method of TC4 titanium alloy rolled pieces provided in this example are basically the same as those in Example 1, except that in step (1), after applying the high-temperature antioxidant, heat and hold at 1040 °C for 4 hours; carry out 6 passes of hot rolling and 3 passes of reverse rolling, with a reduction per pass of 12% and a rolling speed of 5 m / s until the TC4 titanium alloy wide and thick plate is thinned to 40 mm.

[0111] Example 3

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

[0113] Example 4

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

[0115] Example 5

[0116] The method for suppressing edge cracks during the cold rolling of TC4 titanium alloy and the preparation method of TC4 titanium alloy rolled parts provided in this embodiment are basically the same as those in Embodiment 1, except that in step (4), during the cold rolling 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 1 m / s.

[0117] Example 6

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

[0119] Comparative Example 1

[0120] The preparation method of TC4 titanium alloy rolled parts provided in this comparative example is basically the same as that in Embodiment 1, except that in step (3), the first U-shaped fixture is not used, and in step (4), the second U-shaped fixture is not used, but the titanium alloy sheet and the sheet after primary rolling are directly cold rolled.

[0121] In this comparative example, without using the U-shaped fixture, during the cold rolling of the TC4 titanium alloy sheet, some fine cracks will occur during the cold rolling with large reduction, and these cracks will gradually expand as the rolling reduction increases. After two cold rollings, a large number of edge cracks will occur in the TC4 titanium alloy cold rolled sheet.

[0122] Figure 3 It is a picture of the titanium alloy rolled part obtained in Embodiment 1. Figure 4 It is a picture of the titanium alloy rolled part obtained in Comparative Example 1. By comparing Figure 3 and Figure 4It can be seen that the TC4 cold-rolled sheet produced in Comparative Example 1 without using a U-shaped fixture had edge cracks (see Figure 4 ); while the TC4 cold-rolled sheet produced in Example 1 using a U-shaped fixture had no edge cracks (see 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 of Example 1, except that in step (4), the rolling reduction per pass of cold rolling with a small reduction is 10%, the number of rolling passes is 3 passes, and the total reduction after the second edge constraint is 30%.

[0125] Figure 5 Figure for the titanium alloy rolled piece obtained in Comparative Example 2. By comparing Figure 3 and Figure 5 It can be seen that when Example 1 carried out the second cold rolling on the TC4 titanium alloy sheet using the second U-shaped fixture, a low rolling reduction of 5% per pass was adopted, and no cracks occurred in the TC4 titanium alloy cold-rolled sheet during the cold rolling process with the second edge constraint. While in Comparative Example 2, a rolling reduction of 10% per pass was adopted and the total rolling reduction was controlled at 30%, and cracks still occurred. This shows that by controlling the rolling reduction per pass of cold rolling with a small reduction, the present invention can also effectively inhibit the generation of edge cracks.

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

[0127] Table 1 Test results of the mechanical properties of each TC4 titanium alloy rolled piece

[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] It can be seen from Table 1 that the mechanical properties of the TC4 titanium alloy rolled pieces obtained in each example are significantly better than those in each comparative example. This shows that by optimizing the rolling parameters, the present invention can improve the mechanical properties of the TC4 titanium alloy rolled pieces.

[0130] Although the present invention has been illustrated and described with specific embodiments, it should be realized that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; those of ordinary skill in the art should understand that: without departing from the spirit and scope of the present invention, the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for suppressing edge cracks generated during the rolling process of titanium alloy, characterized in that, It includes the following steps: Place the titanium alloy sheet in the first U-shaped fixture for edge restraint, where the titanium alloy sheet and the first U-shaped fixture are in interference fit, and the first U-shaped fixture wraps the titanium alloy sheet, then perform cold rolling with a large reduction, and then remove the first U-shaped fixture to obtain the sheet after primary rolling; Place the sheet after primary rolling in the second U-shaped fixture for edge restraint, where the sheet after primary rolling and the second U-shaped fixture are in interference fit, and the second U-shaped fixture wraps the sheet after primary rolling, then perform cold rolling with a small reduction, and then remove the second U-shaped fixture to obtain the cold-rolled titanium alloy sheet; Wherein, the cross-sectional shapes of the first U-shaped fixture and the second U-shaped fixture are both U-shaped; The rolling reduction per pass of the cold rolling with a small reduction is 2% - 5%, and the total rolling reduction of the cold rolling with a small reduction is 10% - 20%.

2. The method for suppressing edge cracks generated during the rolling process of titanium alloy according to claim 1, characterized in that, Meet at least one of the following conditions: (1) The height of the first U-shaped fixture is equal to the height of the titanium alloy sheet; (2) The height of the second U-shaped fixture is equal to the height of the sheet after primary rolling; (3) The dimensions of the bottom surface and two side surfaces of the first U-shaped fixture match the dimensions of the titanium alloy sheet; (4) The dimensions of the bottom surface and two side surfaces of the second U-shaped fixture match the dimensions of the sheet after primary rolling.

3. The method for suppressing edge cracks generated during the rolling process of titanium alloy 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 generated during the rolling process of titanium alloy according to claim 1, characterized in that, Meet at least one of the following conditions: (1) The rolling reduction per pass of the cold rolling with a large reduction is 5% - 12%; (2) The rolling rate of the cold rolling with a large reduction is 0.01 - 2 m / s; (3) The total rolling reduction of the cold rolling with a large reduction is 20% - 60%; (4) Rolling lubricant is used in each pass of the cold rolling with a large reduction.

5. The method for suppressing edge cracks generated during the rolling process of titanium alloy according to claim 1, characterized in that, Meet at least one of the following conditions: (1) The rolling rate of the cold rolling with a small reduction is 0.01 - 2 m / s; (2) Rolling lubricant is used in each pass of the cold rolling with a small reduction.

6. The method for suppressing edge cracks generated during the rolling process of titanium alloy according to claim 1, characterized in that Before placing the titanium alloy sheet in the first U-shaped fixture, the titanium alloy sheet is subjected to homogenization treatment; The method of the homogenization treatment includes: coating a high-temperature glass protective agent on the titanium alloy sheet, after the high-temperature glass protective agent condenses, perform heat treatment at 700 - 1000 °C for 10 - 120 min, then anneal at 850 °C for 1.5 h, and air-cool.

7. A method for preparing a titanium alloy rolled piece, characterized in that, It includes the method for suppressing edge cracks generated during the rolling of titanium alloy as described in any one of claims 1 - 6.

8. The method for preparing a titanium alloy rolled piece according to claim 7, wherein, The preparation method of the titanium alloy sheet includes: hot-rolling the titanium alloy wide and thick plate; The hot rolling meets at least one of the following conditions: (1) The heating temperature of the hot rolling is 900 - 1040 °C, and the holding time is 0.1 - 20 h; (2) The rolling speed of the hot rolling is 0.1 - 5 m / 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 times.

9. The preparation method of the titanium alloy rolled piece according to claim 8, characterized in that Before the hot rolling, coat a high-temperature anti-oxidant on the titanium alloy wide and thick plate; And / or, after the hot rolling, it further includes the steps of cutting, pickling, and sandblasting.

10. Use of the method for suppressing edge cracks during titanium alloy rolling according to any one of claims 1 to 6 or the method for preparing a titanium alloy rolled product according to any one of claims 7 to 9 in the preparation of a titanium alloy product.

Images