A short flow sheet method for preparing TiAl alloy plate by canning continuous casting and rolling

Abstract

The application discloses a short-process preparation method of TiAl alloy plate by means of box continuous casting and rolling, and relates to the technical field of TiAl alloy preparation.The application aims at solving the problems of low material yield and high cost in the long-process preparation of TiAl alloy plate.The method comprises six procedures, i.e., integral mold manufacturing (box and pouring system are formed), pouring system removal, box hot rolling, annealing of the hot-rolled plate, box removal and post-processing.The method greatly shortens the preparation process and significantly reduces the preparation cost, and can realize the rapid and high-quality preparation of the TiAl alloy plate.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of TiAl alloy preparation, in particular to a short-process preparation method of TiAl alloy plate through package continuous casting and rolling. BACKGROUND

[0002] TiAl alloy has a wide application prospect in the fields of aviation and aerospace and engines due to its light weight and high temperature resistance, a service temperature range of 650-850 DEG C and a density only half of that of a nickel-based high-temperature alloy. However, TiAl alloy has intrinsic brittleness and poor plasticity, and hot plasticity processing such as forging, extrusion and rolling needs to be carried out at an ultra-high temperature of more than 1100 DEG C, otherwise the TiAl alloy prepared through forging, extrusion and rolling will be cracked or even broken, and it is difficult to prepare high-quality materials without defects. In order to keep the temperature in the hot processing process from being reduced to below 1100 DEG C, stainless steel or the like needs to be used to package the TiAl alloy, and the temperature drop in the high-temperature forging, hot extrusion and hot rolling processes is controlled through the package, which has become an important method for the hot plasticity processing of TiAl alloy at home and abroad.

[0003] TiAl alloy plate has a large demand in the fields of aviation and aerospace and engines. At present, the main preparation technologies of TiAl alloy plate include ingot metallurgy technology and powder metallurgy technology. The main process route for preparing the TiAl alloy plate through the ingot metallurgy technology is as follows: TiAl alloy vacuum melting and casting, machining into a cylindrical ingot, ingot packaging, high-temperature package forging or package hot extrusion, heat treatment annealing, package removal, machining into a TiAl square billet, square billet packaging, package hot rolling, hot rolled plate annealing, package removal and post-processing. The ingot metallurgy technology process flow is long, and any defect in any step before the TiAl alloy rolling will cause the plate to be unable to be prepared, so the yield is low, and the cost is very high, which has become the main reason for hindering the application of TiAl alloy plate in the fields of aviation and aerospace.

[0004] CN112916644B, the invention name 《A method for preparing TiAl alloy plate by pack rolling》 discloses: step one, prepare cuboid TiAl alloy blank; step two, pack: according to the size of the blank, process the rolling pack, then put n TiAl alloy blanks with surface protection treatment into the pack, separate the blanks and the pack with a separation layer, the thickness of the separation layer is ≤0.2mm, ensure the distance between the inner surface of the pack structure and the TiAl alloy blank is controlled below 1mm, then seal and weld the pack; step three, hot rolling; step four, creep straightening: control the creep straightening temperature at 950℃-1000℃, apply a load of 150MPa-300MPa to the pack; step five, remove the pack and take out the TiAl alloy plate; step six, TiAl alloy plate surface treatment: treat the TiAl alloy surface as needed to obtain TiAl alloy plate. The separation layer technology used in this patent is to prevent the reaction between TiAl alloy blank and pack. It still needs to cut the cuboid TiAl alloy blank and place it in the pack before hot rolling. The process is complex, and the process before pack hot rolling is basically the same as the above-mentioned ingot metallurgy technology (TiAl alloy vacuum melting → machining into cylindrical ingot → ingot pack → high temperature pack forging or pack hot extrusion → heat treatment annealing → pack removal → machining into TiAl square blank). SUMMARY

[0005] The present application aims to solve the problem of low yield and high cost in the long process of preparing TiAl alloy plate. A short process for preparing TiAl alloy plate by ingot metallurgy is proposed. After vacuum melting of TiAl alloy, the cylindrical ingot is not poured, but directly poured into the whole casting mold composed of rectangular box and pouring system. After removing the pouring system (which can be reused), the TiAl alloy plate is prepared by pack hot rolling.

[0006] The present application provides a short process for preparing TiAl alloy plate by pack continuous casting and rolling. The preparation method is as follows:

[0007] Step one: pack treatment

[0008] The pack has a cavity inside, a separation layer is provided on the surface of the cavity, and a TiAl alloy casting pouring hole is opened on the side of the pack, and a TiAl alloy casting pouring system is installed at the TiAl alloy casting pouring hole, so that the pouring system and the pack form a whole casting mold;

[0009] Step two: TiAl alloy melting and pouring

[0010] Put the whole casting of step one into vacuum melting and casting equipment, then pour the TiAl alloy melt which is melted uniformly according to the component proportion of TiAl alloy into the jacket of the whole casting, so that the melt fills the whole casting, after the molten TiAl alloy solidifies in the jacket, remove the pouring system of the whole casting, and prepare for use;

[0011] Step three: hot-rolling the jacket containing TiAl alloy prepared in step two to obtain a jacket hot-rolled plate; the jacket hot-rolling process parameters are as follows: rolling speed is 10-200 mm / s, pass reduction is 10-60% of the pre-rolling thickness, and total deformation amount of rolling is 40-90%;

[0012] Step four: annealing of the jacket hot-rolled plate

[0013] Put the jacket hot-rolled plate obtained in step three into a heat treatment furnace, anneal at 800-1100℃ for 1-10h, and then cool down with the furnace;

[0014] Step five: jacket removal and post-processing

[0015] Machining the annealed plate to remove the jacket and the isolation layer to obtain a TiAl alloy plate.

[0016] Further, the jacket material in step one is steel material, pure metal or high-temperature resistant alloy, the steel material is stainless steel or heat-resistant steel, the high-temperature resistant alloy is titanium alloy or nickel-based alloy, and the pure metal is pure titanium.

[0017] Further, the jacket thickness in step one is 1-20mm.

[0018] Further, the isolation layer in step one is one or both of metal foil and ceramic powder mixed with adhesive.

[0019] Further, the isolation layer thickness in step one is 0.05-1.0mm.

[0020] Further, the jacket shape in step one is a cuboid with a cavity inside, the internal cavity also maintains a cuboid shape, the internal cuboid cavity is chamfered at each corner, and an oxidation-resistant coating is coated on the outer surface of the jacket.

[0021] Further, the melting method in step two is vacuum induction condensation shell melting, vacuum non-consumable electrode arc melting, vacuum consumable electrode arc melting, electron beam melting or plasma beam melting.

[0022] Further, the jacket is pre-treated before hot-rolling in step three, and the pre-treatment is as follows:

[0023] The sleeve temperature is measured by a temperature measuring device of the vacuum melting and casting equipment, and when the temperature decreases to 1200-1400℃, the TiAl alloy with the sleeve is taken out from the vacuum melting and casting equipment and placed into a hot rolling machine for sleeve hot rolling; or,

[0024] After the TiAl alloy with the sleeve is taken out from the vacuum melting and casting equipment after the overall mold is cooled, the TiAl alloy with the sleeve is heated to 1100-1300℃ again, and then the sleeve hot rolling is performed.

[0025] Further, in the step three, the sleeve hot rolling process parameters are as follows: the rolling speed is 50-100mm / s, the pass reduction is 20-50% of the rolling thickness, and the total deformation amount of rolling is 50-70%.

[0026] Further, in the step four, the sleeve hot rolled plate obtained in the step three is placed into a heat treatment furnace, annealed at 900-1000℃ for 1-10 hours, and then cooled with the furnace.

[0027] The beneficial effects of the present application are as follows:

[0028] The core innovation of the present application is that a completely different process from the existing TiAl alloy plate is adopted: the present application directly pours the melted TiAl alloy into the sleeve, which is different from the existing process of preparing TiAl alloy into ingots and then performing sleeve processing. The method of the present application eliminates the process, solves the problem of preparing ingots and then cutting and loading the ingots into the sleeve, reduces the cost, and saves the process route. Moreover, the existing method cannot produce large-size thick plates of TiAl alloy. The method of ingot + sleeve limits the size of the plate.

[0029] CN112916644B, the invention name 《A method for preparing TiAl alloy plate by sleeve pack rolling》 discloses: step one, preparing a cuboid TiAl alloy blank; step two, sleeve: according to the size of the blank, a rolling sleeve is processed, then n TiAl alloy blanks with surface protection treatment are loaded into the sleeve, the blanks are separated by a separation layer, the thickness of the separation layer is ≤0.2mm, the distance between the inner surface of the sleeve structure and the TiAl alloy blank is controlled to be below 1mm, and the sleeve is then sealed and welded; step three, hot rolling; step four, creep straightening: the creep straightening temperature is controlled at 950℃-1000℃, and a load of 150MPa-300MPa is applied to the sleeve; step five, removing the sleeve and taking out the TiAl alloy plate; step six, TiAl alloy plate surface treatment: according to the needs, the TiAl alloy surface is treated to obtain the TiAl alloy plate.

[0030] The isolation layer technology adopted by the patent is to prevent the TiAl alloy blank from reacting with the package. It is not the same as preventing the smelted TiAl alloy from reacting with the package. Most importantly, the technology of directly pouring the smelted TiAl alloy into the package is brand new and has not been reported, so it is unclear whether the technology of the patent is suitable for preventing the smelted TiAl alloy from reacting with the package.

[0031] (1) The traditional ingot metallurgy preparation technology of TiAl alloy plate has a long process, mainly including vacuum melting, ingot processing, ingot packaging, package forging or package hot extrusion, heat treatment annealing, package removal, square billet processing, square billet packaging, package hot rolling, hot rolled plate annealing, package removal, and post-processing. The present application significantly shortens the preparation process of TiAl alloy plate, mainly only having six processes of overall mold manufacturing (package and pouring system), pouring system removal, package hot rolling, hot rolled plate annealing, package removal, and post-processing. The main process is reduced by half, the processing cost is significantly reduced, the preparation time of TiAl alloy plate is saved, the rapid manufacturing of the plate is realized, and therefore, the cost of TiAl alloy plate is inevitably greatly reduced, which is convenient for large-scale production and is conducive to the popularization and application in the fields of aerospace and civil use.

[0032] (2) In the traditional ingot metallurgy technology, the package forging or package extrusion related process is an important step for preparing a hot-rolled square billet (if a cylindrical ingot is used for rolling, the material utilization is too low). How to control the temperature drop in the process of forging or extrusion is a key technology. Generally, multiple times of package forging or hot extrusion are adopted to ensure a high hot working temperature, which increases the complexity and difficulty of preparation, and defects are easily generated in the process of hot working of TiAl alloy package, thereby causing the failure of hot rolling. The present application eliminates the process of package forging or package extrusion, reduces the process in which defects are easily generated in TiAl alloy, and therefore, the yield of TiAl alloy plate is inevitably significantly improved, which is equivalent to reducing the preparation cost of TiAl alloy plate.

[0033] Therefore, the method for preparing TiAl alloy plate by package continuous casting and rolling is a rapid and high-quality method for preparing TiAl alloy plate, has obvious cost advantage, can meet the important needs of the aerospace and engine fields for TiAl alloy plate, can be popularized to the civil application field, has important commercial value, and has obvious economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a schematic view of an overall mold formed by a pouring system and a package;

[0035] Figure 2A morphology diagram of a Ti-43.5Al-4Nb-1Mo-0.1B alloy plate;

[0036] Figure 3 A morphology diagram of a Ti-43Al-9V-0.2Y alloy plate. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the spirit of the present application will be described in detail below, and any person skilled in the art can make changes and modifications to the technology taught by the present application without departing from the spirit and scope of the present application after understanding the embodiments of the present application.

[0038] The illustrative embodiments of the present application and the descriptions thereof are used to explain the present application, but are not as limitations on the present application.

[0039] Embodiment 1

[0040] The nominal composition of the TiAl alloy is Ti-43.5Al-4Nb-1Mo-0.1B (at.%), and the TiAl alloy with this composition is prepared into a plate by canned continuous casting and rolling, and the specific process is as follows:

[0041] (1) Canned preparation: the shape of the can is a cuboid with a cavity inside, the internal cavity also maintains a cuboid shape, the internal cuboid cavity is chamfered (R5) at each corner, the thickness of the can is 7 mm, the can material is 304 stainless steel, the outer surface of the can is coated with an oxidation-resistant coating, and the internal cavity surface is separated from the TiAl alloy to be subsequently poured into the can by a separation layer, the separation layer is a metal foil with a thickness of 0.3 mm. The can is prepared by machining and welding. A hole is opened in the center of the side of the cuboid can, and a pouring system (including a sprue, a runner and a nozzle cup) for casting TiAl alloy is installed at the opening, so that the pouring system and the can form an integrated mold (as shown in the schematic diagram Figure 1

[0042] (2) TiAl alloy smelting and pouring: place the above-mentioned integrated mold into a vacuum induction skull melting and casting equipment, then smelt and pour according to the composition ratio of the TiAl alloy using the vacuum melting and casting equipment, after uniform smelting, pour the TiAl alloy melt into the integrated mold, the pouring mode is centrifugal pouring, so that the melt fills the mold, and the molten TiAl alloy solidifies in the can.

[0043] ​(3) TiAl alloy cladding hot rolling: The cladding temperature is measured by the temperature measuring device of the vacuum melting equipment. When the temperature decreases to 1300℃, the whole casting mold after pouring is quickly taken out from the vacuum melting equipment, the pouring system is quickly removed, and the TiAl alloy with the cladding is put into the hot rolling machine for cladding hot rolling to prepare the TiAl alloy hot rolling plate with cladding. The cladding hot rolling process parameters are: the rolling speed is 50 mm / s, the pass reduction is 30% of the pre-rolling thickness, and the total deformation amount of rolling is 80%.

[0044] (4) Annealing of cladding hot rolling plate: The cladding hot rolling plate obtained in the above step is put into a heat treatment furnace and annealed at 900℃ for 3 hours, and then cooled in the furnace.

[0045] (5) Cladding removal and post-processing: The annealed plate is machined to remove the cladding and the isolation layer to obtain the TiAl alloy plate. The appearance of the Ti-43.5Al-4Nb-1Mo-0.1B alloy plate after surface machining and straightening at high temperature is shown in Figure 2 .

[0046] Example 2:

[0047] The nominal composition of the TiAl alloy is Ti-43Al-9V-0.2Y (at.%). The cladding continuous casting and rolling process is used to prepare the plate of the TiAl alloy with the composition, and the specific process is as follows:

[0048] (1) Cladding preparation: The cladding shape is a cuboid with an internal cavity, the internal cavity also maintains a cuboid shape, the internal cuboid cavity corners are chamfered (R3), the cladding thickness is 12 mm, the cladding material is heat-resistant steel, the cladding outer surface is coated with an oxidation-resistant coating, and the internal cavity surface is coated with an isolation layer to isolate the cladding from the TiAl alloy subsequently poured into the cladding. The isolation layer is coated with yttrium oxide ceramic powder mixed with a binder, or both are used together, and the isolation layer thickness is 0.8 mm. The cladding can be prepared by machining and welding. A hole is opened in the center of the side edge of the cuboid cladding, and a pouring system (including a sprue, a runner and a nozzle cup) for casting TiAl alloy is installed at the opening to form a whole casting mold (as shown in Figure 1 ).

[0049] (2) TiAl alloy smelting and pouring: The whole casting mold is put into a vacuum consumable electrode arc melting and casting equipment, and then the vacuum melting and casting equipment is used to smelt and pour according to the composition ratio of the TiAl alloy. After uniform smelting, the TiAl alloy melt is poured into the whole casting mold, the pouring mode is gravity pouring, the melt fills the mold, and the molten TiAl alloy solidifies in the cladding.

[0050] (3) TiAl alloy cladding hot rolling: after the whole casting mold is cooled and taken out in the vacuum melting equipment, the pouring system is removed, and the TiAl alloy with the cladding is reheated to 1260℃, cladding hot rolling is carried out, and the TiAl alloy hot rolling plate with the cladding is prepared. The cladding hot rolling process parameters are: the rolling speed is 30mm / s, the pass reduction is 35% of the pre-rolling thickness, and the total deformation amount of rolling is 85%.

[0051] (4) Annealing of the cladding hot rolling plate. The cladding hot rolling plate obtained in the above step is placed into a heat treatment furnace, annealed at 850℃ for 5 hours, and then cooled with the furnace.

[0052] (5) Cladding removal and post-processing: the annealed plate is machined to remove the cladding and the isolation layer, and the TiAl alloy plate is obtained. The appearance of the Ti-43Al-9V-0.2Y alloy plate after surface machining and straightening at high temperature is shown in FIG. 1. Figure 3

[0053] In addition to the above specific embodiments, any preparation method obtained according to the present application and any improvement or change made on the basis of the present application are included in the scope of the present patent.​

Claims

1. A short-process method for preparing sheet metal using TiAl alloy cladding continuous casting and rolling, characterized in that... The method for preparing the board material is as follows: Step 1: Wrapping Process The sleeve has an internal cavity, an isolation layer is provided on the surface of the cavity, and a TiAl alloy casting pouring hole is opened on the side of the sleeve. A TiAl alloy casting pouring system is installed at the TiAl alloy casting pouring hole, so that the pouring system and the sleeve form an integral mold. The sleeve is made of steel, pure metal, or high-temperature resistant alloy. The sleeve thickness is 1-20mm. The isolation layer is one or two of metal foil and ceramic powder mixed with binder. The isolation layer thickness is 0.05-1.0mm. Step 2: TiAl alloy melting and casting Place the integral mold from step one into a vacuum casting equipment, and then pour the TiAl alloy melt, which has been uniformly melted in the vacuum casting equipment according to the composition ratio of the TiAl alloy, directly into the sleeve of the integral mold so that the melt fills the integral mold. After the molten TiAl alloy solidifies in the sleeve, remove the gating system of the integral mold for later use. Step 3: The TiAl alloy-containing cladding obtained in Step 2 is hot-rolled to obtain a cladding hot-rolled plate; the cladding hot-rolling process parameters are: rolling speed of 10-200 mm / s, reduction per pass of 10-60% of the initial thickness, and total deformation of 40-90%; Pre-treatment is performed before hot rolling of the sheath, and the pre-treatment is as follows: The cladding temperature is measured by the temperature measuring device in the vacuum casting equipment. When the temperature drops to 1200-1400℃, the clad TiAl alloy is removed from the vacuum casting equipment and placed in a hot rolling mill for cladding hot rolling; or... After the overall mold in the vacuum casting equipment cools down, the TiAl alloy with the cladding is taken out, reheated to 1100-1300℃, and then hot rolled with the cladding. Step 4: Annealing of the encased hot-rolled plate The hot-rolled cladding plate obtained in step three is placed in a heat treatment furnace and annealed at 800-1100℃ for 1-10 hours, and then cooled in the furnace. Step 5: Removal of the outer sheath and post-processing The annealed sheet material is machined to remove the cladding and isolation layer, resulting in a TiAl alloy sheet.

2. The method for preparing sheet metal by TiAl alloy cladding continuous casting and rolling in a short process according to claim 1, characterized in that... The sleeve described in step one is a cuboid with an internal cavity, and the internal cavity also maintains the shape of a cuboid. All corners of the internal cuboid cavity are chamfered, and an anti-oxidation coating is applied to the outer surface of the sleeve.

3. The method for preparing sheet metal by continuous casting and rolling of TiAl alloy cladding according to claim 1, characterized in that... The melting method described in step two is vacuum induction solidification melting, vacuum non-consumable electrode arc melting, vacuum consumable electrode arc melting, electron beam melting, or plasma beam melting.

4. The method for preparing sheet metal by continuous casting and rolling of TiAl alloy cladding according to claim 1, characterized in that... The hot rolling process parameters in step three are: rolling speed of 50-100 mm / s, reduction per pass of 20-50% of the thickness before rolling, and total deformation of 50-70%.

5. The method for preparing sheet metal by continuous casting and rolling of TiAl alloy cladding according to claim 1, characterized in that... In step four, the hot-rolled cladding plate obtained in step three is placed in a heat treatment furnace and annealed at 900-1000℃ for 1-10 hours, and then cooled in the furnace.

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