Sleeve suitable for hot rolling of TiAl alloy plate and sheathing method

Abstract

The invention belongs to the technical field of titanium alloy preparation, and particularly relates to a sheath and method suitable for TiAl alloy plate hot rolling, the sheath comprises an upper cover plate, a lower cover plate, a first edging and a second edging, the upper cover plate and the lower cover plate are both TC4 alloy, and the first edging and the second edging are both pure titanium or TC4 alloy; the first edge strip and the second edge strip are used for being in contact with the two sides of the TiAl blank in the non-rolling mill entering and exiting direction and welded to the TiAl blank; the upper cover plate and the lower cover plate are used for covering the upper surface and the lower surface of the TiAl blank and welded to the first edge strip and the second edge strip, and the upper cover plate and the lower cover plate on the two sides of the wrapping sleeve in the rolling mill entering and exiting direction are directly subjected to closing-in welding. The short-process efficient hot rolling of the TiAl alloy plate is realized by reducing the cost of the sheathing material and simplifying the sheathing process. And the sheath structure and the manufacturing process are simple, the sheath reliability is high in the hot rolling process, and the method plays a positive role in industrialized batch preparation of TiAl alloy plates.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy preparation, and in particular relates to a sheathing and a sheathing method suitable for hot rolling of a TiAl alloy plate. Background Art

[0002] High-temperature titanium alloys have become key materials for modern aircraft engines due to their high specific strength, excellent corrosion resistance and high temperature resistance (creep resistance, long-lasting strength and structural stability, etc.). They are used in aircraft engine disks, casings, blades and other components to reduce the weight of the aircraft, thereby improving the thrust-to-weight ratio of the aircraft. Typical high-temperature titanium alloys (Ti-1100, IMI834, Ti60 and Ti600, etc.) have good structural and performance stability at 600°C, but are not suitable for working temperatures above 600°C. TiAl intermetallic compounds have low density (3.9~4.2 g / cm 3 ), high elastic modulus (elastic modulus at room temperature reaches 170 GPa, about 150 GPa at 750℃, equivalent to GH4169), high specific strength, high specific stiffness, low expansion coefficient, high thermal conductivity, oxidation resistance, creep resistance and excellent fatigue performance. It has stable performance in the temperature range of 700℃~900℃, and can be used for a short time within 1100℃. Lightweight and high temperature resistant TiAl alloy sheets have great application potential in aircraft skins, integral wall panels and wing rudders, which will effectively improve the comprehensive performance of aircraft.

[0003] However, TiAl intermetallic compounds have disadvantages such as low plasticity, high resistance to thermal deformation, and narrow thermal processing window, which makes plate rolling difficult and prone to cracking during plate processing. As we all know, sheath rolling technology is widely used in the production of traditional titanium alloy plates, so reasonable sheath design is an important way to achieve the preparation of TiAl alloy plates.

[0004] At present, traditional sheath materials are high-temperature titanium alloys and stainless steels that have similar high-temperature deformation coordination with TiAl alloys, and vacuum electron beam welding is performed. The economic and time costs of sheath material processing and welding in the sheath preparation process are high, which is not suitable for the industrial production of TiAl alloy sheets.

[0005] For example, patent CN117225922A performs subsequent rolling work by designing a special-shaped sheath for TiAl alloy. This method isolates the TiAl alloy from the outside air by vacuum electron beam welding of a stainless steel sheath, which, on the one hand, reduces the temperature drop rate of the TiAl alloy during the rolling process, and on the other hand, avoids oxidation of the TiAl alloy during heating, rolling, and cooling after rolling. However, this method has high economic and time costs, whether it is the processing method of the sheath material (machining grooves) or the welding method (vacuum electron beam welding), which is not conducive to the mass production of TiAl products.

[0006] The sheath material in patent CN112958626A is Inconel 625 high temperature alloy, and in order to prevent the risk of FeTi reaction between TiAl alloy and outer sheath material, Nb and Ta foil are added as isolation materials. The economic cost of sheath and isolation materials in this method is high, and it is only suitable for experimental work of small-sized TiAl alloy, which is not conducive to the commercial promotion and production of TiAl products.

[0007] Therefore, developing low-cost and simple sheathing and sheathing methods suitable for hot rolling of TiAl alloy sheets in industrial production is an urgent need to realize the commercial application of TiAl alloy sheets. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a low-cost and simple sheathing and sheathing method suitable for hot rolling of TiAl alloy plates, which can not only play the same role as the traditional sheathing method in slowing down the temperature drop of TiAl alloy during rolling, but also achieve the dual reduction of economic and time costs in the sheathing preparation process. The sheathing cost is low and simple, which is conducive to the large-scale industrial production of TiAl alloy plates.

[0009] The present invention is specifically implemented through the following technical solutions.

[0010] The present invention provides a sheath suitable for hot rolling of TiAl alloy plates, the sheath comprising an upper cover plate, a lower cover plate, a first side strip and a second side strip, the upper cover plate and the lower cover plate are both TC4 alloy, and the first side strip and the second side strip are both pure titanium or TC4 alloy.

[0011] The first side strip and the second side strip are used to contact the two sides of the TiAl billet in the direction not entering or exiting the rolling mill, and are welded to the TiAl billet; the upper cover plate and the lower cover plate are used to cover the upper and lower surfaces of the TiAl billet, and are welded to the first side strip and the second side strip at the corresponding positions, and the upper cover plate and the lower cover plate on both sides of the direction of entering or exiting the rolling mill are used for closing welding.

[0012] The sheath provided by the present invention can not only play the same role as the traditional sheathing method in slowing down the temperature drop of TiAl alloy during rolling, but also achieves a dual reduction in economic and time costs during the sheathing preparation process, which is helpful for the large-scale industrial production of TiAl alloy plates.

[0013] Preferably, the thickness of the upper cover plate and the lower cover plate is 1 mm to 2 mm. The purpose of the design of the upper cover plate and the lower cover plate is to cover the TiAl billet and the edge strip, prevent the TiAl billet from directly contacting the roller, reduce the risk of cracking of the TiAl billet during rolling, and maintain a good surface quality of the TiAl alloy sheet. In order to prevent the risk of reaction between the TiAl billet and the outer sheath material, and at the same time, the strength of industrial pure titanium is too low during rolling, which can easily cause the upper cover plate and the lower cover plate to break, thereby causing the roller to directly contact the TiAl billet, increasing the risk of cracking of the TiAl alloy during rolling, so the TC4 alloy sheet with low cost and easy rolling force to act better on the TiAl billet is selected.

[0014] Preferably, the thickness of the first side strip and the second side strip is 105%-120% of the thickness of the TiAl billet, the width of the first side strip and the second side strip is 5%-30% of the width of the TiAl billet, and the length is consistent with the length of the TiAl billet. The function of the first side strip and the second side strip is to insulate the edge of the TiAl to prevent edge cracking during hot rolling, thereby improving the rolling success rate and the quality of the plate. In order to prevent the risk of reaction between the TiAl billet and the outer sheath material, slow down the temperature drop of the TiAl alloy during rolling (especially the edge of the plate), and have good high-temperature deformability, low-cost industrial pure titanium (TA1, TA2, TA3, etc.) or TC4 alloy is selected as the side strip of the sheath.

[0015] Preferably, the TiAl billet contains γ phase, including TNM alloy, TNB alloy and TiAl-V alloy.

[0016] Preferably, the first side strip or the second side strip is not used on both sides of the direction in which the jacket enters and exits the rolling mill.

[0017] The present invention also provides the above-mentioned sheathing method suitable for hot rolling of TiAl alloy plates, comprising the following steps: Step 1, manufacturing the upper cover plate and the lower cover plate: TC4 alloy is selected as the material of the upper cover plate and the lower cover plate, and the size of the TC4 alloy is determined according to the size of the TiAl billet.

[0018] Step 2, edge strip production: use industrial pure titanium or TC4 alloy as the first edge strip and the second edge strip.

[0019] Step 3, side strip welding: the first side strip and the second side strip are tightly contacted with both sides of the TiAl blank and welded by argon arc welding to obtain an intermediate structure.

[0020] Step 4, welding of the cover plates: the upper cover plate and the lower cover plate are covered on the upper and lower surfaces of the intermediate structure in step 3, and the structure welded in step 3 is welded to the upper cover plate and the lower cover plate by argon arc welding, and the upper cover plate and the lower cover plate are welded to the first side strip and the second side strip at the corresponding position. Since the upper cover plate and the lower cover plate and the first side strip and the second side strip have good weldability, and the economic and time costs of argon arc welding are low, argon arc welding can be used to achieve good welding of the first side strip, the second side strip and the upper cover plate and the lower cover plate in step 3, and vacuum electron beam welding is not required. It should be noted that if there are special circumstances where argon arc welding cannot be used, vacuum electron beam welding can also be used.

[0021] Preferably, since the two sides of the jacket entering and exiting the rolling mill are not welded to the TiAl billet using side strips in step 3, the upper cover plate and the lower cover plate on both sides of the jacket entering and exiting the rolling mill are directly welded during the cover plate welding process in step 4. Argon arc welding can be used for welding. If there are special circumstances where argon arc welding cannot be used, vacuum electron beam welding can also be used.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a novel low-cost and simple sheathing and sheathing method for hot-rolled TiAl alloy plates, which can not only play the same role as the traditional sheathing method in slowing down the temperature drop of TiAl alloy during rolling, but also achieves the dual reduction of economic and time costs in the sheathing preparation process, which is helpful for the industrial production of TiAl alloy plates in large quantities. Specifically, it is embodied in:

[0023] The sheath of the present invention includes an upper cover plate, a lower cover plate, a first side strip and a second side strip. The first side strip and the second side strip are used to contact the two sides of the TiAl billet in the non-entry and exit directions of the rolling mill and are welded to the TiAl billet; the upper cover plate and the lower cover plate are used to cover the upper and lower surfaces of the TiAl billet and are welded to the first side strip and the second side strip at the corresponding positions. The upper cover plate and the lower cover plate on both sides of the sheath in the entry and exit directions of the rolling mill are directly welded. The upper cover plate and the lower cover plate of the present invention are made of TC4 alloy thin plates. The TC4 outer sheath does not react with the TiAl alloy at high temperatures, thereby preventing the Fe-Ti reaction risk existing in traditional carbon steel and stainless steel as sheath materials. Although TC4 alloy does not have the same deformation coordination as TiAl billet during high-temperature rolling, due to its small thickness (1mm~2mm), it is easier to transmit the rolling force during the rolling process compared with the traditional thicker steel sleeve, avoiding the phenomenon that the rolling force cannot be transmitted to the TiAl billet layer during the hot rolling process, and ensuring that the TiAl billet is effectively deformed in each rolling pass.

[0024] The sheath provided by the present invention does not use a relatively expensive high-temperature alloy as a sheath material, and does not use an isolation material or coating between the TiAl blank and the outer sheath. At the same time, the weldability of TC4 alloy and industrial pure titanium is good, and the sheath welding can be performed using ordinary argon arc welding, and vacuum electron beam welding is not required. The weld has good stability and is not prone to cracking, thereby improving the reliability of the sheath during the rolling process. Whether in terms of material selection, sheath design or welding, both economic and time costs are reduced, and it is suitable for sheath rolling of various TiAl alloys under different process conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the sheath structure suitable for hot rolling of TiAl alloy plates according to the present invention.

[0026] Explanation of the accompanying drawings: 1. upper cover plate, 2. lower cover plate, 3. first side strip, 4. second side strip, 5. TiAl blank.

[0027] Figure 2 This is a physical picture of the package prepared in Example 1.

[0028] Figure 3 In the figure, (a) is a physical picture of the TiAl alloy prepared by using the traditional steel sheath in comparative example 1 before the sheath is disassembled, and (b) is a physical picture after the sheath is disassembled.

[0029] Figure 4 In the figure, (a) is a real picture of the TiAl alloy prepared in Example 1 before the sheath is disassembled, and (b) is a real picture after the sheath is disassembled.

[0030] Figure 5 This is a photo of the TiAl alloy prepared in comparative example 2 after the sheath is disassembled. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention. The experimental methods and detection methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0032] The present invention provides a low-cost simple package suitable for hot rolling of TiAl alloy plates, such as Figure 1 As shown, the cover comprises an upper cover plate 1, a lower cover plate 2, a first side strip 3 and a second side strip 4. The upper cover plate 1 and the lower cover plate 2 are both TC4 alloys, and the first side strip 3 and the second side strip 4 are both pure titanium or TC4 alloys.

[0033] The first side strip 3 and the second side strip 4 are used to contact the two sides of the TiAl billet 5 in the non-entry and exit directions, and are welded to the TiAl billet 5; the upper cover plate 1 and the lower cover plate 2 are used to cover the upper and lower surfaces of the TiAl billet 5, and are welded to the first side strip 3 and the second side strip 4 at the corresponding positions, and the upper cover plate 1 and the lower cover plate 2 on both sides of the entry and exit directions of the rolling mill are directly welded.

[0034] The cover plates are an upper cover plate 1 and a lower cover plate 2: the cover plate materials used are TC4 alloy thin plates with uniform thickness (about 1.0 mm-2.0 mm), the purpose of which is to cover the TiAl billet 5, the first side strip 3 and the second side strip 4 to prevent the TiAl billet 5 from directly contacting the rollers, reduce the risk of cracking of the TiAl billet during rolling, and maintain good surface quality.

[0035] The edge strips are the first edge strip 3 and the second edge strip 4. The edge strip material used is industrial pure titanium (TA1, TA2, TA3, etc.) or TC4 alloy, and the edge strip thickness is 105%-120% of the thickness of the TiAl billet. Since the TiAl alloy has poor room temperature plasticity, it cannot be deformed by cold working. At the same time, it has high resistance to thermal deformation and a narrow thermal working window. During the hot rolling process, obvious cracks will occur at the edge, resulting in failure of the hot rolling operation. Therefore, the purpose of adding the first edge strip 3 and the second edge strip 4 is to keep the TiAl edge warm, prevent it from cracking during the hot rolling process, and improve the rolling success rate and plate quality.

[0036] The welding is performed by argon arc welding. If there are special circumstances where argon arc welding cannot be used, vacuum electron beam welding can be used.

[0037] TiAl billet: The TiAl billet contains γ phase, including TNM alloy, TNB alloy and TiAl-V alloy.

[0038] The present invention also provides the low-cost and simple sheathing method applicable to hot rolling of TiAl alloy plates, comprising the following steps: Step 1, manufacturing the upper cover plate and the lower cover plate: selecting TC4 alloy as the material of the upper cover plate and the lower cover plate, and determining the size of the TC4 alloy according to the size of the TiAl billet; Step 2, edge strip production: use industrial pure titanium or TC4 alloy as the first edge strip and the second edge strip; Step 3, side strip welding: the first side strip and the second side strip are closely contacted with both sides of the TiAl blank and welded by argon arc welding; Step 4, welding of cover plates: The structure welded in step 3 is welded to the upper cover plate and the lower cover plate by argon arc welding. Since the upper cover plate, the lower cover plate and the first side strip and the second side strip have good weldability, and the economic and time costs of argon arc welding are low, argon arc welding can be used to achieve good welding of the side strips and the upper and lower cover plates in step 3.

[0039] Preferably, since no side strips are used to weld the TiAl billet to the two sides of the sheath entering and exiting the rolling mill in step 3, during the cover plate welding process in step 4, the upper cover plate and the lower cover plate on both sides of the sheath entering and exiting the rolling mill are directly welded using argon arc welding.

[0040] The present invention can not only play the same role as the traditional sheathing method in slowing down the temperature drop of TiAl alloy during rolling, but also achieves the dual reduction of economic and time costs in the sheathing preparation process, which is conducive to the large-scale industrial production of TiAl alloy plates.

[0041] It should be noted that the present invention is applicable to hot rolling of TiAl alloy plates. No intermediate insulating material or insulating agent is added between the outer sheath material and the TiAl billet, but the addition of an intermediate insulating material or insulating agent may also realize the present invention. Therefore, adding an intermediate insulating material or insulating agent is an alternative. Among them, the role of the intermediate insulating material is to prevent the outer sheath material from reacting with the inner billet during the heating or rolling process of the sheath, specifically including high-melting-point metals such as niobium, molybdenum, and tungsten; the role of the insulating agent is to facilitate the separation between the outer sheath material and the inner billet after hot rolling, specifically refers to the insulating agent used in the metal processing process. At the same time, the present invention does not need to use vacuum electron beam welding to weld the various components. The use of vacuum electron beam welding to weld the various components may also realize the present invention. Therefore, the use of vacuum electron beam welding to weld the various components is an alternative.

[0042] The present invention will be specifically described below by means of the following examples and comparative examples.

[0043] Example 1 The upper and lower cover plates used in this embodiment are made of TC4 alloy with a thickness of 1 mm. The edge strip material is industrial pure titanium TA2. The TiAl alloy used is an alloy with a nominal composition of Ti-41.2Al-2.65Nb-1.2Cr-0.7Mo (TNM alloy), and the composition is in atomic percentage.

[0044] A sheathing method suitable for hot rolling of TiAl alloy plates comprises the following steps: Step 1, blank preparation: the original blank is prepared by vacuum consumable electrode arc melting + hot isostatic pressing, and the square blank with a thickness of 12 mm × width of 320 mm × length of 400 mm is made by electric spark wire cutting.

[0045] Step 2, production of the upper cover plate and the lower cover plate: TC4 alloy is selected as the material of the upper cover plate and the lower cover plate, with a thickness of 1 mm, and the size of the TC4 alloy is determined according to the size of the TiAl billet.

[0046] Step 3, edge strip production: Use industrial pure titanium (TA2) as the first edge strip and the second edge strip, and use the first edge strip and the second edge strip to closely contact the TiAl blank. The thickness of the first edge strip and the second edge strip is 110% of the thickness of the TiAl blank, the width of the first edge strip and the second edge strip is 20% of the width of the TiAl blank, and the length of the first edge strip and the second edge strip is consistent with the length of the TiAl blank.

[0047] Step 4, side strip welding: the first side strip and the second side strip are brought into close contact with the TiAl blank and are welded together by argon arc welding.

[0048] Step 5, welding of cover plates: weld the first side strip and the second side strip to the TiAl blank and then weld them to the upper and lower cover plates by argon arc welding; since the upper and lower cover plates and the side strips have good weldability, and the economic and time costs of argon arc welding are low, argon arc welding can be used to achieve good welding of the side strips and the upper and lower cover plates. Figure 2 shown.

[0049] Rolling process: Jacket rolling: The welded jacket and the blank are heated to 1240°C in a hydrogen heat treatment furnace, and rolled 5 times at a rolling rate of 50 mm / s and a single-pass deformation of 10%, with a cumulative total deformation of 50%, and air-cooled to room temperature; the blank is returned to the furnace for 5 minutes of insulation between every two rolling passes.

[0050] Jacket removal: The jacket of the rolled plate is removed by water jet processing, and a straight TiAl alloy plate is obtained after annealing and correction at 900℃.

[0051] Example 2 The upper and lower cover plates used in this embodiment are made of TC4 alloy with a thickness of 1 mm. The edge strip material is industrial pure titanium TA1. The TiAl alloy used is an alloy with a nominal composition of Ti-41.2Al-2.65Nb-1.2Cr-0.7Mo (TNM alloy), and the composition is in atomic percentage.

[0052] A sheathing method suitable for hot rolling of TiAl alloy plates comprises the following steps: Step 1, billet preparation: The original billet is prepared by vacuum consumable electrode arc melting + hot isostatic pressing, and the square billet of 12×320×400 mm is made by electric spark wire cutting.

[0053] Step 2, production of the upper cover plate and the lower cover plate: TC4 alloy is selected as the material of the upper cover plate and the lower cover plate, with a thickness of 1 mm, and the size of the TC4 alloy is determined according to the size of the TiAl billet.

[0054] Step 3, edge strip production: Use industrial pure titanium (TA1) as the first edge strip and the second edge strip, and use the first edge strip and the second edge strip to closely contact the TiAl blank. The thickness of the first edge strip and the second edge strip is 110% of the thickness of the TiAl blank, the width of the first edge strip and the second edge strip is 20% of the width of the TiAl blank, and the length of the first edge strip and the second edge strip is consistent with the length of the TiAl blank.

[0055] Step 4, side strip welding: the first side strip and the second side strip are brought into close contact with the TiAl blank and are welded together by argon arc welding.

[0056] Step 5, welding of cover plates: After welding the first side strip and the second side strip to the TiAl blank, they are welded to the upper cover plate and the lower cover plate by argon arc welding; since the upper cover plate, the lower cover plate and the side strips have good weldability, and the economic and time costs of argon arc welding are low, argon arc welding can be used to achieve good welding of the first side strip and the second side strip and the upper cover plate and the lower cover plate.

[0057] Rolling process: Jacket rolling: The welded jacket and the blank are heated to 1240°C in a hydrogen heat treatment furnace, and rolled 5 times at a rolling rate of 50 mm / s and a single-pass deformation of 10%, with a cumulative total deformation of 50%, and air-cooled to room temperature; the blank is returned to the furnace for 5 minutes of insulation between every two rolling passes.

[0058] Jacket removal: The jacket of the rolled plate is removed by water jet processing, and a straight TiAl alloy plate is obtained after annealing and correction at 900℃.

[0059] Example 3 The upper and lower cover plates used in this embodiment are made of TC4 alloy with a thickness of 1 mm. The edge strip material is industrial pure titanium TA3. The TiAl alloy used is an alloy with a nominal composition of Ti-41.2Al-2.65Nb-1.2Cr-0.7Mo (TNM alloy), and the composition is in atomic percentage.

[0060] A sheathing method suitable for hot rolling of TiAl alloy plates comprises the following steps: Step 1, billet preparation: The original billet is prepared by vacuum consumable electrode arc melting + hot isostatic pressing, and the square billet of 12×320×400 mm is made by electric spark wire cutting.

[0061] Step 2, production of the upper cover plate and the lower cover plate: TC4 alloy is selected as the material of the upper cover plate and the lower cover plate, with a thickness of 1 mm, and the size of the TC4 alloy is determined according to the size of the TiAl billet.

[0062] Step 3, edge strip production: Use industrial pure titanium (TA3) as the first edge strip and the second edge strip, and use the first edge strip and the second edge strip to closely contact the TiAl blank. The thickness of the first edge strip and the second edge strip is 110% of the thickness of the TiAl blank, the width of the first edge strip and the second edge strip is 20% of the width of the TiAl blank, and the length of the first edge strip and the second edge strip is consistent with the length of the TiAl blank.

[0063] Step 4, side strip welding: the first side strip and the second side strip are brought into close contact with the TiAl blank and are welded together by argon arc welding.

[0064] Step 5, welding of cover plates: After welding the first side strip and the second side strip to the TiAl blank, they are welded to the upper cover plate and the lower cover plate by argon arc welding; since the upper cover plate, the lower cover plate and the first side strip and the second side strip have good weldability, and the economic and time costs of argon arc welding are low, argon arc welding can be used to achieve good welding of the side strips and the upper and lower cover plates.

[0065] Rolling process: Jacket rolling: The welded jacket and the blank are heated to 1240°C in a hydrogen heat treatment furnace, and rolled 5 times at a rolling rate of 50 mm / s and a single-pass deformation of 10%, with a cumulative total deformation of 50%, and air-cooled to room temperature; the blank is returned to the furnace for 5 minutes of insulation between every two rolling passes.

[0066] Jacket removal: The jacket of the rolled plate is removed by water jet processing, and a straight TiAl alloy plate is obtained after annealing and correction at 900℃.

[0067] Example 4 A sheathing method suitable for hot rolling of TiAl alloy plates comprises the following steps: Step 1, blank preparation: the original blank is prepared by vacuum consumable electrode arc melting + hot isostatic pressing, and is made into a 12×320×400mm square billet by electric spark wire cutting; the TiAl alloy has a nominal composition of Ti-41.2Al-2.65Nb-1.2Cr-0.7Mo, and the composition is atomic percentage.

[0068] Step 2, production of the upper cover plate and the lower cover plate: TC4 alloy is selected as the material of the upper cover plate and the lower cover plate, with a thickness of 1 mm, and the size of the TC4 alloy is determined according to the size of the TiAl billet.

[0069] Step 3, edge strip production: titanium alloy (TC4) is used as the first edge strip and the second edge strip, and the first edge strip and the second edge strip are in close contact with the TiAl blank. The thickness of the first edge strip and the second edge strip is 110% of the thickness of the TiAl blank, the width of the first edge strip and the second edge strip is 20% of the width of the TiAl blank, and the length of the first edge strip and the second edge strip is consistent with the length of the TiAl blank.

[0070] Step 4, side strip welding: the first side strip and the second side strip are brought into close contact with the TiAl blank and are welded together by argon arc welding.

[0071] Step 5, welding of cover plates: After welding the first side strip and the second side strip to the TiAl blank, they are welded to the upper cover plate and the lower cover plate by argon arc welding; since the upper cover plate, the lower cover plate and the side strips have good weldability, and the economic and time costs of argon arc welding are low, argon arc welding can be used to achieve good welding of the side strips and the upper and lower cover plates.

[0072] Rolling process: Jacket rolling: The welded jacket and the blank are heated to 1240°C in a hydrogen heat treatment furnace, and rolled 5 times at a rolling rate of 50 mm / s and a single-pass deformation of 10%, with a cumulative total deformation of 50%, and air-cooled to room temperature; the blank is returned to the furnace for 5 minutes of insulation between every two rolling passes.

[0073] Jacket removal: The jacket of the rolled plate is removed by water jet processing, and a straight TiAl alloy plate is obtained after annealing and correction at 900℃.

[0074] Comparative Example 1 The rolling process is carried out using a steel ladle sleeve. The specific steps are as follows: Step 1, billet preparation: The original billet is prepared by vacuum consumable electrode arc melting + hot isostatic pressing, and the square billet of 12×320×400 mm is made by electric spark wire cutting.

[0075] Step 2, production of the upper cover plate and the lower cover plate: stainless steel (such as 310S) is selected as the material of the upper cover plate and the lower cover plate, and the size of the TC4 alloy is determined according to the size of the TiAl billet.

[0076] Step 3, edge strip production: stainless steel (such as 310S) is used as the first edge strip and the second edge strip, and the first edge strip and the second edge strip are in close contact with the TiAl blank.

[0077] Step 4, welding the edge strips and the cover plate: weld the upper cover plate and the lower cover plate in step 2 with the first edge strip and the second edge strip in step 3 by argon arc welding, and then use a vacuum electron beam welder.

[0078] Step 5, sheath rolling: heat the welded sheath and the blank to 1240°C in a hydrogen heat treatment furnace, roll them 5 times at a rolling rate of 50 mm / s and a single-pass deformation of 10%, with a cumulative total deformation of 50%, and air cool to room temperature; return to the furnace for 5 minutes between every two rolling passes.

[0079] Step 6, sheath removal: the sheath of the rolled plate in step 6 is removed by water jet processing, and a straight TiAl alloy plate is obtained after annealing and correction at 900°C.

[0080] Figure 3 In the figure, (a) is a real picture of the TiAl alloy prepared by using a traditional steel sheath before the sheath is disassembled, and (b) is a real picture after the sheath is disassembled. Compared with Comparative Example 1, the sheath condition and plate quality after rolling used in Example 1 are better, such as Figure 4 As shown in (a) and (b), there is almost no adhesion between the cover and the plate in Example 1, the cover is easy to remove, there is no trace of chemical reaction on the surface of the plate, no cracking, and the surface quality is good.

[0081] The performance of the remaining embodiments is similar to that of Embodiment 1 and will not be described in detail.

[0082] Comparative Example 2 The 4mm TC4 plate is used for rolling, and the specific steps are as follows: Step 1, blank preparation: the original blank is prepared by vacuum consumable electrode arc melting + hot isostatic pressing, and is made into a 12×320×400mm square billet by electric spark wire cutting; the TiAl alloy has a nominal composition of Ti-41.2Al-2.65Nb-1.2Cr-0.7Mo, and the composition is atomic percentage.

[0083] Step 2, production of upper and lower cover plates: Select TC4 plates with a thickness of 4 mm as the materials for the upper and lower cover plates, and determine the size of the TC4 alloy according to the size of the TiAl billet.

[0084] Step 3, edge strip production: TC4 sheet is used as the first edge strip and the second edge strip, and the first edge strip and the second edge strip are in close contact with the TiAl blank. The thickness of the first edge strip and the second edge strip is 110% of the thickness of the TiAl blank, the width of the first edge strip and the second edge strip is 20% of the width of the TiAl blank, and the length of the first edge strip and the second edge strip is consistent with the length of the TiAl blank.

[0085] Step 4, welding the edge strips and the cover plate: weld the upper cover plate and the lower cover plate in step 2 with the first edge strip and the second edge strip in step 3 by argon arc welding, and then use a vacuum electron beam welder.

[0086] Step 5, sheath rolling: heat the welded sheath and the blank to 1240°C in a hydrogen heat treatment furnace, roll them 5 times at a rolling rate of 50 mm / s and a single-pass deformation of 10%, with a cumulative total deformation of 50%, and air cool to room temperature; return to the furnace for 5 minutes between every two rolling passes.

[0087] Step 6, sheath removal: the sheath of the rolled plate is removed by water jet processing, and a straight TiAl alloy plate is obtained after annealing at 900°C and correction.

[0088] Comparative Example 2: 4 mm thick TC4 plate was rolled, and the case of removing the sheath was as follows: Figure 5 ,from Figure 5 It can be seen from the figure that the sheath and the internal TiAl alloy of this comparative example cannot be separated. Figure 5 It can be seen that the edge of the TiAl alloy has broken.

[0089] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, they are also intended to be included.

Claims

1. A sheath suitable for hot rolling of TiAl alloy sheet, characterized in that: The package comprises an upper cover plate, a lower cover plate, a first side strip and a second side strip, the upper cover plate and the lower cover plate are both TC4 alloy, and the first side strip and the second side strip are both pure titanium or TC4 alloy; The first side strip and the second side strip are used to contact the two sides of the TiAl billet in the non-in-out rolling mill direction and are welded to the TiAl billet; the upper cover plate and the lower cover plate are used to cover the upper and lower surfaces of the TiAl billet and are welded to the first side strip and the second side strip, and the upper cover plate and the lower cover plate on both sides of the in-out rolling mill direction are used for closing welding; The thickness of the upper cover plate and the lower cover plate is 1 mm to 2 mm.

2. The sheath suitable for hot rolling of TiAl alloy sheet according to claim 1, characterized in that: The thickness of the first side strip and the second side strip is 105%-120% of the thickness of the TiAl blank, the width of the first side strip and the second side strip is 5%-30% of the width of the TiAl blank, and the length of the first side strip and the second side strip is consistent with the length of the TiAl blank.

3. The sheath suitable for hot rolling of TiAl alloy sheet according to claim 1, characterized in that: The pure titanium is TA1, TA2 or TA3.

4. The sheath suitable for hot rolling of TiAl alloy sheet according to claim 1, characterized in that: The welding is performed by argon arc welding.

5. The sheath suitable for hot rolling of TiAl alloy sheet according to claim 1, characterized in that: The welding is performed by using vacuum electron beam.

6. The sheath suitable for hot rolling of TiAl alloy sheet according to claim 1, characterized in that: The TiAl blank contains a γ phase.

7. The sheath suitable for hot rolling of TiAl alloy sheet according to claim 6, characterized in that: The TiAl billet is a TNM alloy, a TNB alloy or a TiAl-V alloy.

8. The sheathing method suitable for hot rolling of TiAl alloy sheet according to claim 1, characterized in that: The following steps are involved: TC4 alloy is selected as the material of the upper cover plate and the lower cover plate, and the size of TC4 alloy is determined according to the size of TiAl billet; Use industrial pure titanium or TC4 alloy as the first and second edge strips; The first side bar and the second side bar are closely contacted with both sides of the TiAl billet in a direction other than the direction of entering and exiting the rolling mill, and are welded with the TiAl billet to obtain an intermediate structure; The upper cover plate and the lower cover plate are covered on the upper surface and the lower surface of the middle structure, and the upper cover plate and the lower cover plate are welded with the first side strip and the second side strip; the upper cover plate and the lower cover plate on both sides of the sheath entering and exiting the rolling mill are directly welded.

9. The sheathing method for hot rolling of TiAl alloy sheet according to claim 8, characterized in that: The edge strip welding and cover plate welding are carried out by argon arc welding or vacuum electron beam welding.

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