Preparation method of TA15 foil

Abstract

The invention discloses a method for preparing TA15 foil, which comprises the following steps of: smelting a TA15 titanium alloy cast ingot by adopting vacuum electromagnetic suspension, and forging, hot rolling and cold rolling the TA15 titanium alloy cast ingot to prepare the TA15 foil with the thickness of 0.05-0.08 mm, the thickness error of + / -0.005 mm, the width of less than or equal to 350mm and the width deviation of + / -1mm. The TA15 titanium alloy cast ingot is smelted through vacuum electromagnetic suspension, on one hand, the smelting temperature and pressure are accurately controlled, and the component segregation phenomenon is reduced; and on the other hand, the pollution risk caused by crucible contact is thoroughly eliminated, and the TA15 titanium alloy cast ingot with high quality and high purity can be obtained. Due to the fact that the chemical components of the TA15 titanium alloy material can be accurately controlled through vacuum electromagnetic suspension smelting, fluctuation of the chemical components is reduced, the raw material smelting process is not polluted, and the TA15 foil which is excellent in microscopic structure and mechanical property and qualified in size precision can be prepared.

Description

Technical Field

[0001] The invention relates to the technical field of titanium material processing, and in particular to a method for preparing a TA15 foil. Background Art

[0002] TA15 foil has a high melting point of about 1660℃ and has good high temperature resistance. It is used to manufacture solid parts of aircraft and engines, such as decorative nets on jet engine combustion tubes, metal composite heat protection tiles and titanium multilayer walls in space shuttle heat protection systems, etc. With the application of TA15 foil in the electronics industry and other fields, the requirements for thickness accuracy and ultra-thin specifications of TA15 foil are getting higher and higher.

[0003] The existing technology uses vacuum consumable arc melting (VAR) to prepare TA15 titanium alloy ingots, and then rolls the TA15 titanium alloy ingots into TA15 foils. Since TA15 titanium alloy materials contain alloying elements such as aluminum, molybdenum, and zirconium, element segregation is prone to occur in TA15 titanium alloy materials during vacuum consumable arc melting. Due to the fluctuation of the composition of TA15 titanium alloy materials, the material properties are unstable, which causes uneven deformation in the subsequent rolling process, and then produces defect cracks, which seriously affects the quality of TA15 foils. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a method for preparing TA15 foil.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A method for preparing TA15 foil comprises the following steps: Determine the alloy element ratio according to the target composition range of the TA15 titanium alloy ingot, and determine the smelting raw materials according to the alloy element ratio; perform vacuum electromagnetic suspension smelting on the smelting raw materials to prepare a TA15 titanium alloy ingot, wherein the TA15 titanium alloy ingot has a diameter of 200-240 mm and a mass of 50-100 kg; Forging the TA15 titanium alloy ingot to prepare a hot-rolled slab; Hot rolling the hot-rolled slab to prepare a cold-rolled slab; The cold-rolled slab is cold-rolled to prepare a TA15 foil; the thickness of the TA15 foil is 0.05-0.08 mm, the thickness error is ±0.005 mm, and the width of the TA15 foil is ≤350 mm, and the width deviation is ±1 mm.

[0006] According to the method for preparing TA15 foil provided by an embodiment of the present invention, the step of determining the alloy element ratio value according to the target composition range of the TA15 titanium alloy ingot, and determining the smelting raw material according to the alloy element ratio value includes: The target composition range is Al: 5.5-7.1; V: 0.8-2.5; Zr: 1.5-2.5; Mo: 0.5-2.0; based on the target composition range, the alloy element ratio is determined to be Al: 6.5; V: 1.5; Zr: 2.0; Mo: 1.0; based on the alloy element ratio, the smelting raw materials are determined to be titanium sheets, vanadium blocks, molybdenum blocks, zirconium blocks and aluminum sheets.

[0007] According to the method for preparing TA15 foil provided by an embodiment of the present invention, the step of performing vacuum electromagnetic suspension melting on the smelting raw material comprises: The smelting raw materials are placed in a water-cooled crucible of a vacuum electromagnetic levitation furnace according to the melting points and shapes of the smelting raw materials, and vacuum electromagnetic levitation smelting is performed on the smelting raw materials in the water-cooled crucible.

[0008] According to the method for preparing TA15 foil provided by an embodiment of the present invention, the step of performing vacuum electromagnetic suspension melting on the smelting raw material in the water-cooled crucible comprises: The smelting raw material is smelted once, the smelting current is 300-1100A, and the cooling time is 90min-120min to prepare a primary ingot; The primary ingot is reversed and subjected to secondary smelting, wherein the smelting current setting value and holding time are the same as those of the primary smelting, so as to prepare the secondary ingot; The secondary ingot is reversed and smelted three times, with the smelting current setting value and holding time being the same as those of the primary smelting, to prepare a TA15 titanium alloy ingot.

[0009] According to the method for preparing TA15 foil provided by an embodiment of the present invention, the step of forging the TA15 titanium alloy ingot to prepare a hot-rolled slab comprises: The TA15 titanium alloy ingot is heated to 750-780°C, kept warm for 100-120 minutes, then heated to 980-1050°C at a heating rate of 10-15°C / min, kept warm for 120-150 minutes; and then free forging is performed to prepare a hot-rolled slab with a thickness of 50-80 mm and a width of 280-300 mm.

[0010] According to the method for preparing TA15 foil provided by an embodiment of the present invention, the step of hot-rolling the hot-rolled slab to prepare a cold-rolled slab comprises: The hot-rolled slab is heated to 900-950°C for hot rolling to prepare the cold-rolled slab with a thickness of 1-1.5 mm; the holding time is 40-60 minutes, and the final rolling temperature is not less than 800°C; the reduction amount in each pass is 5%-10%; as the thickness of the cold-rolled slab decreases, the reduction amount decreases.

[0011] According to the method for preparing TA15 foil provided by an embodiment of the present invention, the step of hot-rolling the hot-rolled slab to prepare a cold-rolled slab further includes: During the hot rolling process, the cold-rolled slab is subjected to intermediate annealing, the number of annealing is 1-2 times, the annealing temperature is 750-850° C., and the annealing time is 40-60 min.

[0012] According to the method for preparing TA15 foil provided by an embodiment of the present invention, after the step of hot-rolling the hot-rolled slab to prepare a cold-rolled slab, the method further comprises: The cold-rolled slab is pickled at a temperature of 30-50° C. for 5-15 minutes using a mixed solution of 10%-15% nitric acid and 1%-3% hydrofluoric acid.

[0013] According to the method for preparing TA15 foil provided by an embodiment of the present invention, the step of cold rolling the cold-rolled slab to prepare TA15 foil comprises: The cold-rolled slab is cold-rolled by a twenty-roll cold rolling mill with a working roll diameter of 20 mm-30 mm to prepare a TA15 foil; the reduction amount in each pass is between 20% and 50%, and the reduction amount decreases as the TA15 foil becomes thinner.

[0014] The method for preparing the TA15 foil provided in an embodiment of the present invention further comprises, after the step of cold rolling the cold-rolled slab: The cold-rolled TA15 foil is subjected to vacuum annealing heat treatment, the annealing temperature is 500-650° C., and the annealing time is 2-6 hours.

[0015] The advantages and beneficial effects of the present invention are: The preparation method of TA15 foil provided in the present application adopts vacuum electromagnetic suspension melting of TA15 titanium alloy ingots, and forges, hot rolls and cold rolls the TA15 titanium alloy ingots to prepare TA15 foil with a thickness of 0.05-0.08mm, a thickness error of ±0.005mm, a width of ≤350mm, and a width deviation of ±1mm. By vacuum electromagnetic suspension melting of TA15 titanium alloy ingots, on the one hand, precise control of melting temperature and pressure helps to thoroughly melt various alloy raw materials, fully and evenly mix the elements, reduce component segregation, and ensure that the chemical composition is precisely controlled; on the other hand, since vacuum suspension melting uses electromagnetic force to suspend the raw materials in the air for melting, the risk of contamination caused by crucible contact is completely eliminated, ensuring that the raw materials only undergo the expected alloying reaction during the entire melting process, maintaining the purity of the raw materials, and thus facilitating the acquisition of high-quality, high-purity TA15 titanium alloy ingots. Since vacuum electromagnetic levitation melting can accurately control the chemical composition of TA15 titanium alloy materials and reduce chemical composition fluctuations, and the raw material melting process will not be contaminated, it can ensure that the TA15 titanium alloy material is uniformly deformed during the subsequent rolling process, avoid defects and cracks during the rolling process, and be able to produce TA15 foil with excellent microstructure and mechanical properties and qualified dimensional accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic flow chart of a method for preparing TA15 foil in an embodiment of the present invention; Figure 2 Schematic diagram of the change of melting current in vacuum electromagnetic suspension melting in an embodiment of the present invention; Figure 3 Schematic diagram of the change of melting current when the melt climbs the wall in vacuum electromagnetic suspension melting in an embodiment of the present invention; Figure 4 is a schematic structural diagram of a vacuum suspension melting furnace according to an embodiment of the present invention; Figure 5 It is a schematic diagram of welding a plurality of TA15 titanium alloy ingots into a consumable electrode in an embodiment of the present invention.

[0017] 1. TA15 titanium alloy ingot; 2. Consumable electrode; 3. Water-cooled crucible; 4. Induction coil. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0019] Figure 1 Schematic diagram of the process of preparing TA15 foil in an embodiment of the present invention. Figure 1As shown, the present application provides a method for preparing a TA15 foil, comprising the following steps: S1: determining alloy element ratio values ​​according to the target composition range of the TA15 titanium alloy ingot, and determining smelting raw materials according to the alloy element ratio values; performing vacuum electromagnetic suspension smelting on the smelting raw materials to prepare a TA15 titanium alloy ingot, wherein the TA15 titanium alloy ingot has a diameter of 200-240 mm and a mass of 50-100 kg; S2: forging the TA15 titanium alloy ingot to prepare a hot-rolled slab; S3: hot rolling the hot-rolled slab to prepare a cold-rolled slab; S4: cold rolling the cold rolled slab to prepare TA15 foil; the thickness of the TA15 foil is 0.05-0.08 mm, the thickness error is ±0.005 mm, the width of the TA15 foil is ≤350 mm, and the width deviation is ±1 mm.

[0020] The preparation method of TA15 foil provided in the present application adopts vacuum electromagnetic suspension melting of TA15 titanium alloy ingots, and forges, hot rolls and cold rolls the TA15 titanium alloy ingots to prepare TA15 foil with a thickness of 0.05-0.08mm, a thickness error of ±0.005mm, a width of ≤350mm, and a width deviation of ±1mm. By vacuum electromagnetic suspension melting of TA15 titanium alloy ingots, on the one hand, precise control of melting temperature and pressure helps to thoroughly melt various alloy raw materials, fully and evenly mix the elements, reduce component segregation, and ensure that the chemical composition is precisely controlled; on the other hand, since vacuum suspension melting uses electromagnetic force to suspend the raw materials in the air for melting, the risk of contamination caused by crucible contact is completely eliminated, ensuring that the raw materials only undergo the expected alloying reaction during the entire melting process, maintaining the purity of the raw materials, and thus facilitating the acquisition of high-quality, high-purity TA15 titanium alloy ingots. Since vacuum electromagnetic levitation melting can accurately control the chemical composition of TA15 titanium alloy materials and reduce chemical composition fluctuations, and the raw material melting process will not be contaminated, it can ensure that the TA15 titanium alloy material is uniformly deformed during the subsequent rolling process, avoid defects and cracks during the rolling process, and be able to produce TA15 foil with excellent microstructure and mechanical properties and qualified dimensional accuracy.

[0021] Figure 5 Schematic diagram of welding a plurality of TA15 titanium alloy ingots into a consumable electrode in an embodiment of the present invention, such as Figure 5As shown, in some embodiments, after the step of vacuum electromagnetic suspension melting of the smelting raw materials, it also includes: welding a plurality of TA15 titanium alloy ingots by an electron beam welding box to prepare consumable electrodes, and melting the consumable electrodes by vacuum consumable arc to prepare large-sized TA15 titanium alloy ingots to improve production efficiency. The number of welded TA15 titanium alloy ingots can be flexibly adjusted according to actual needs to meet the diversified requirements of rolling.

[0022] When welding is performed by an electron beam welding box, the welding current is 1-3A, the welding voltage is 30KV, and the welding speed is 20-50mm / min. When using an electron beam welding box for welding, due to the very high energy density of the electron beam, the electron beam can be focused to a very small diameter. This high energy density can achieve high-precision welding, which can make the weld very narrow and have a large aspect ratio, which helps to improve production efficiency and greatly shorten the welding time. The width of the annular weld is 80-100mm and the depth is 30-50mm. Since the other parts of the TA15 titanium alloy ingot are less affected by heat during the welding process, thermal deformation and thermal stress can be reduced, and cracks in the annular weld due to thermal stress after welding can be prevented.

[0023] In some embodiments, the alloy element ratio is determined according to the target composition range of the TA15 titanium alloy ingot, and the step of determining the smelting raw material according to the alloy element ratio includes: The target composition range is Al: 5.5-7.1; V: 0.8-2.5; Zr: 1.5-2.5; Mo: 0.5-2.0; the alloy element ratio is determined according to the target composition range to be Al: 6.5; V: 1.5; Zr: 2.0; Mo: 1.0; the smelting raw materials are determined according to the alloy element ratio to be titanium sheet, vanadium block, molybdenum block, zirconium block and aluminum sheet. Metal raw materials of any shape can be smelted by vacuum electromagnetic levitation smelting, such as block, powder, sheet, chip, sponge and other shapes. Since the metal raw materials have no contact with the water-cooled crucible under the action of the Lorentz force during the smelting process, the impurities in the water-cooled crucible are avoided from contaminating the metal raw materials, and the purity of the TA15 titanium alloy ingot is improved. In addition, since the smelting temperature of the vacuum electromagnetic levitation smelting equipment exceeds 3000℃, the refractory metals V and Mo can be fully smelted.

[0024] In some embodiments, argon gas is filled in the furnace chamber of the vacuum electromagnetic levitation furnace so that the pressure inside the furnace chamber is 1000-4000 Pa. Melting in a protective gas atmosphere with a pressure of 1000-4000 Pa can suppress the volatilization of aluminum elements, thereby ensuring that the alloy composition can strictly meet the design requirements from the beginning to the end of melting, providing a solid foundation for producing TA15 titanium alloy with stable and consistent performance.

[0025] Since argon is an inert protective gas, it fills the smelting space and excludes any active gases that may exist, further reducing the risk of metal oxidation or nitridation and improving the purity of the alloy. The presence of argon can also make the smelting environment more stable. In the vacuum magnetic levitation smelting process, the metal raw materials are suspended and heated to melt under the action of electromagnetic force. Argon can act as a buffer to reduce the splashing and volatilization of the melt. For example, when the melt may experience some fluctuations or tiny splashing at high temperatures, argon can suppress this situation, making the smelting process more stable and helping to accurately control smelting parameters such as temperature and smelting time.

[0026] As a gas medium, argon can affect the transfer of heat to a certain extent. During the smelting process, it can help evenly distribute heat and make the metal raw materials heated more evenly. For vacuum magnetic levitation melting, a process that requires precise temperature control, this characteristic of argon helps ensure that all parts of the metal raw materials can reach the appropriate melting temperature, thereby promoting the homogenization of alloy components and reducing the phenomenon of component segregation.

[0027] In some embodiments, the step of performing vacuum electromagnetic suspension melting on the smelting raw material includes: The smelting raw materials are placed in a water-cooled crucible of a vacuum electromagnetic levitation furnace according to the melting points and shapes of different smelting raw materials, and vacuum electromagnetic levitation smelting is performed on the smelting raw materials in the water-cooled crucible. Specifically, gaps are set between the vanadium blocks, molybdenum blocks and zirconium blocks, and titanium sheets and aluminum sheets are located in the gaps so that liquid titanium and aluminum can surround the vanadium blocks, molybdenum blocks and zirconium blocks, so that these block raw materials can be more easily mixed with liquid titanium and aluminum after melting, and the composition of the entire melt is made more uniform through convection.

[0028] Figure 2 FIG. 1 is a schematic diagram of the variation of the melting current in vacuum electromagnetic levitation melting in an embodiment of the present invention. Figure 2 As shown, the steps of performing vacuum electromagnetic suspension melting on the smelting raw materials in the water-cooled crucible include: The smelting raw material is melted once, the melting current is 300-1100A, and the cooling time is 90min-120min to prepare a primary ingot; At the beginning, the melting current is 300A, which is maintained for 3 minutes; it is increased from 300A to 400A, which is maintained for 2 minutes; it is increased from 400A to 500A, which is maintained for 2 minutes; it is increased from 500A to 600A, which is maintained for 2 minutes; it is increased from 600A to 750A, which is maintained for 2 minutes; it is increased from 750A to 850A, which is maintained for 1 minute; it is increased from 850A to 950A, which is maintained for 30 seconds; it is increased from 950A to 1100A, which is maintained for 5 seconds; then it is kept warm for 5 minutes, and the melting power is 480-500kw. The raw materials for melting are completely melted, and then the power is reduced to the minimum (80kw) within 10 seconds, and the power is turned off. The primary ingot is cooled in a water-cooled crucible for 1.5 hours before being taken out of the furnace. After being taken out of the furnace, the primary ingot is cooled to room temperature outside the furnace, and then a secondary melting is carried out.

[0029] By slowly increasing the temperature and increasing the current in stages, it is ensured that the raw materials are fully melted and the composition is uniform, and internal stress or local overheating of the material caused by too fast a temperature increase is avoided, which affects the quality of the ingot. In some embodiments, after the smelting is completed, the heat is kept for 5 minutes, and then the current is reduced and the power is turned off for cooling. This precisely controlled heating, heat preservation and cooling process helps to further optimize the organizational structure and composition uniformity of the ingot and improve the quality of the ingot.

[0030] The primary ingot is reversed and subjected to secondary smelting, with the smelting current setting value and cooling time being the same as those of the primary smelting to prepare the secondary ingot; The secondary ingot was reversed and smelted three times with the same smelting current setting value and cooling time as the primary smelting to prepare TA15 titanium alloy ingot.

[0031] Figure 3 Schematic diagram of the change of melting current when the melt climbs the wall in vacuum electromagnetic suspension melting in an embodiment of the present invention. Figure 4 Schematic diagram of the structure of the vacuum suspension melting furnace in the embodiment of the present invention. Figure 3 and Figure 4As shown, in order to ensure that the alloy ingot melts under effective support, the power is adjusted according to the state of the molten pool. That is, when the alloy ingot begins to sink, the power is increased in time to ensure that the alloy ingot is melted under effective magnetic support to prevent the unmelted ingot from sinking quickly to the bottom of the crucible. During the melting process, if the molten metal climbs the wall of the water-cooled crucible, the temperature is raised twice. Specifically, the heating power is reduced from 480KW-500KW (current 1100A) to 700-900A, maintained for 5-8S, and then increased to 480KW-500KW again. After the smelting starts, the smelting current and smelting voltage are passed through the induction coil, and the cold-rolled residue inside the water-cooled crucible begins to melt. When the smelting is completed, the heating power is reduced from 500KW to 80KW within 10-20S, and then the power is turned off to avoid the ingot and the crucible from sticking due to the power reduction rate being too fast or too slow. During the ingot removal process, two people work together, one operates the hydraulics, and the other uses a basin to hold the ingot under the water-cooled crucible.

[0032] In some embodiments, the melt is strongly stirred under the action of electromagnetic force to improve the composition uniformity of the TA10 titanium alloy ingot. Specifically, at a frequency of 10 kHz, as the current increases from 300 A to 1100 A, the flow velocity of the melt increases, and the flow pattern and vortex position remain unchanged, but the flow velocity is accelerated. Therefore, the stirring effect of the melt can be enhanced by increasing the current.

[0033] In some embodiments, the step of forging a TA15 titanium alloy ingot to prepare a hot-rolled slab comprises: The TA15 titanium alloy ingot is heated to 750-780°C, kept warm for 100-120 minutes, then heated to 980-1050°C at a heating rate of 10-15°C / min, and kept warm for 120-150 minutes; then free forging is performed to prepare hot-rolled slabs with a thickness of 50-80 mm and a width of 280-300 mm.

[0034] During the forging process, the first heating to 750℃ is mainly to allow the ingot to be heated slowly and preliminarily. In the initial state, the internal structure of the titanium alloy ingot may be uneven, and if the temperature is raised too quickly, large thermal stress will be generated due to the temperature difference between the inside and outside. Keeping at 750℃ for 100 minutes can gradually make the temperature inside and outside the ingot consistent, reduce the generation of thermal stress, and also prepare for the subsequent organizational homogenization. It can avoid defects such as cracks in the ingot caused by rapid temperature changes and large temperature differences between the inside and outside of the ingot, and also avoid rapid heating that is not conducive to the slow adjustment and homogenization of the internal structure, causing the organizational transformation in some areas to be too rapid.

[0035] TA15 titanium alloy will undergo different phase transformations at different temperatures. During the first heating to 750℃, the titanium alloy has begun some initial phase transformations or structural adjustments. The heating rate of 10℃ / min from 750℃ to 980-1050℃ is to accurately control the phase transformation process. Different heating rates will affect the kinetics of phase transformation. A heating rate of 10-15℃ / min can ensure that the phases in the alloy transform as expected. Keeping at 980-1050℃ for 120-150min is to enable TA15 titanium alloy to complete important phase transformations in this critical temperature range, and to fully homogenize the newly formed phases, so as to obtain an ideal microstructure to achieve the mechanical properties and processing properties required for hot rolling.

[0036] The TA15 titanium alloy ingot can be heated by a resistance furnace or a gas furnace to ensure heating uniformity.

[0037] In some embodiments, the forging speed is controlled between 50-200 mm / s. This speed range can ensure that the material has enough time for dynamic recrystallization to refine the grains during the deformation process, and can also prevent stress concentration caused by excessive deformation speed from causing cracks, thereby ensuring that the forging process is stable and reliable.

[0038] In some embodiments, the step of hot rolling the hot-rolled slab to prepare the cold-rolled slab comprises: The hot-rolled slab is heated to 900-950°C for hot rolling to prepare the cold-rolled slab with a thickness of 1-1.5 mm; the holding time is 40-60 minutes, and the final rolling temperature is not less than 800°C; the reduction amount in each pass is 5%-10%; as the thickness of the cold-rolled slab decreases, the reduction amount decreases.

[0039] A reversible hot rolling mill with precise pressure reduction control system and good plate shape control capability is selected, and a continuous heating furnace is used to ensure uniform temperature of the plate during rolling. The hot-rolled slab is heated to 900-950℃ for hot rolling, which can not only maintain the good plasticity of the material for rolling deformation, but also help control grain growth and ensure the stability of the plate's organizational properties. The final rolling temperature is not lower than 800℃ to ensure that rolling is completed at a higher temperature, which is conducive to the uniformity of material deformation and control of organizational properties. If the final rolling temperature is too low, the plasticity of the material will decrease, and residual stress and cracks will easily occur, affecting the quality of the plate.

[0040] In some embodiments, the rolling speed is adjusted according to the equipment performance and the plate thickness, and the rolling speed range is 1-5m / s. As the plate becomes thinner, the speed can be appropriately increased, but it must not exceed the maximum value allowed by the equipment, so as to ensure the surface quality of the hot-rolled slab while ensuring production efficiency, and avoid problems such as scratches and cracks caused by excessive speed.

[0041] In some embodiments, the step of hot rolling the hot-rolled slab to prepare the cold-rolled slab further includes: During the hot rolling process, the cold-rolled slab is subjected to intermediate annealing, the number of annealing is 1-2 times, the annealing temperature is 750-850℃, and the annealing time is 40-60min. The furnace cooling or the cooling rate is controlled within the range of 20-50℃ / min to effectively eliminate the work hardening, improve the material plasticity and uniformity of the organization, and provide a good organizational state for subsequent rolling.

[0042] In some embodiments, a shot blasting process is used to treat the defects such as oxide scale and impurities that may exist on the surface of the plate after hot rolling. The shot blasting intensity and time are reasonably adjusted according to the surface condition of the plate and the process requirements to ensure effective removal of the surface oxide scale, improve the surface roughness, enhance the adhesion between the plate surface and the subsequent treatment medium, prepare for the pickling and cold rolling processes, and avoid excessive shot blasting to damage the plate substrate.

[0043] In some embodiments, after the step of hot rolling the hot-rolled slab to prepare the cold-rolled slab, the method further comprises: The cold-rolled slab is pickled at a temperature of 30-50°C and a pickling time of 5-15 minutes. A mixed solution of 10%-15% nitric acid and 1%-3% hydrofluoric acid is used for pickling. The pickling temperature is strictly controlled between 30-50°C. The pickling time is determined according to the surface condition of the plate and the concentration of the pickling solution, ranging from 5-15 minutes. During the pickling process, the oxide scale and other impurities remaining on the surface of the plate are removed, and the surface is slightly corroded to further improve the surface quality. After pickling, water washing and neutralization treatment are carried out to prevent the acid residue from corroding the plate and ensure that the surface quality of the plate meets the requirements of subsequent processes.

[0044] In some embodiments, the step of cold rolling the cold-rolled slab to prepare the TA15 foil comprises: The TA15 foil is produced by cold rolling the cold-rolled slab through a twenty-roll cold rolling mill with a working roll diameter of 20mm-30mm; the reduction per pass is between 20%-50%, and the reduction decreases as the TA15 foil becomes thinner. By selecting working rolls with a diameter of 20mm-30mm for cold rolling, the contact area between the working rolls and the cold-rolled slab is reduced, the total rolling force is reduced, and energy saving is achieved. At the same time, the number of rolling passes can be reduced, reducing production costs. As the TA15 foil becomes thinner, the reduction decreases, avoiding the foil from rupture due to excessive deformation resistance.

[0045] The use of a twenty-roller cold rolling mill has many advantages: using advanced control technology and high-precision sensors, the processing accuracy can be controlled within a few tenths of a millimeter, which can meet the high-precision requirements of different customers; based on the multi-roller working principle, multiple pressing and extrusion can be automatically controlled and operated continuously, improving processing efficiency and production capacity; the pressing force is uniform, which can avoid quality problems such as deformation of the material due to uneven pressure; the rolling speed can reach 1030 meters / min, with high-speed rolling capabilities; the frame is integrally cast steel, with high longitudinal and lateral rigidity, and can roll out TA15 foil with high thickness accuracy and flatness.

[0046] In some embodiments, the thickness of the TA15 foil is 0.05-0.08 mm, and the rolling speed is 10-15 m / min, which improves production efficiency while ensuring good thickness accuracy and surface quality, and avoids problems such as excessive thickness deviation or surface scratches.

[0047] In some embodiments, the pre-tension of cold rolling is between 5-20 MPa, and the post-tension is between 3-15 MPa. Appropriate tension can ensure the smooth operation of the foil during rolling, reduce plate shape defects, and help improve the dimensional accuracy of the foil.

[0048] In some embodiments, after the step of cold rolling the cold-rolled slab, the method further comprises: The cold-rolled TA15 foil is subjected to vacuum annealing heat treatment with a vacuum degree of 10 -3 -10 -5 Pa, annealing temperature is 500-650℃, annealing time is 2-6h. By precisely controlling the annealing temperature and time, the residual stress of the foil is eliminated while avoiding excessive grain growth, ensuring that the foil has good mechanical properties and dimensional stability to meet product use requirements.

[0049] In some embodiments, the TA15 foil is passivated to form a passivation film on the surface of the TA15 foil. Specifically, a passivation film with a thickness of 5-20 nanometers is formed on the surface of the TA15 foil by electrochemical deposition or chemical conversion film technology. The passivation film with uniform thickness and dense structure can significantly improve the corrosion resistance of the TA15 foil.

[0050] A specific embodiment of the preparation method of the TA15 foil of the present application is described below: The target composition range of TA15 titanium alloy ingot is Al: 5.5-7.1; V: 0.8-2.5; Zr: 1.5-2.5; Mo: 0.5-2.0, and the alloy element ratio is Al: 6.5; V: 1.5; Zr: 2.0; Mo: 1.0. According to the alloy element ratio, the smelting raw materials are determined to be titanium sheets, vanadium blocks, molybdenum blocks, zirconium blocks and aluminum sheets. According to the melting point and shape of different smelting raw materials, the smelting raw materials are placed in the water-cooled crucible of the vacuum electromagnetic suspension furnace, and the smelting raw materials in the water-cooled crucible are subjected to vacuum electromagnetic suspension melting.

[0051] The raw materials for smelting are melted once. At the beginning, the smelting current is 300A, which is maintained for 3 minutes; it is increased from 300A to 400A, which is maintained for 2 minutes; it is increased from 400A to 500A, which is maintained for 2 minutes; it is increased from 500A to 600A, which is maintained for 2 minutes; it is increased from 600A to 750A, which is maintained for 2 minutes; it is increased from 750A to 850A, which is maintained for 1 minute; it is increased from 850A to 950A, which is maintained for 30 seconds; it is increased from 950A to 1100A, which is maintained for 5 seconds; then it is kept warm for 5 minutes, and the smelting power is 480-500kw. The raw materials for smelting are completely melted, and then the power is reduced to the minimum (80kw) within 10 seconds, and the power is turned off. The primary ingot is cooled in a water-cooled crucible for 1.5 hours and then taken out of the furnace to prepare the primary ingot. The primary ingot is reversed and smelted twice. The smelting current setting value and cooling time are the same as those of the primary smelting to prepare the secondary ingot. The secondary ingot was reversed and smelted for the third time, with the same smelting current setting value and cooling time as the first smelting to prepare a TA15 titanium alloy ingot with a diameter of 200 mm and a feed amount of 100 kg.

[0052] The TA15 titanium alloy ingot is heated to 750-780°C, kept warm for 100-120 minutes, then heated to 980-1050°C at a heating rate of 10-15°C / min, kept warm for 120-150 minutes; and then free forging is performed to prepare hot-rolled slabs with a thickness of 50-80 mm and a width of 280-300 mm.

[0053] The hot-rolled slab is heated to 900-950℃ for hot rolling to prepare a cold-rolled slab with a thickness of 1-1.5mm; the holding time is 40-60min, and the final rolling temperature is not less than 800℃; the reduction amount per pass is 5%-10%; as the thickness of the cold-rolled slab decreases, the reduction amount decreases. During the hot rolling process, the cold-rolled slab is subjected to intermediate annealing, the annealing number is 1-2 times, the annealing temperature is 750-850℃, and the annealing time is 40-60min. The cold-rolled slab is pickled, the pickling temperature is 30-50℃, and the pickling time is 5-15min.

[0054] The cold-rolled slab is cold-rolled by a Sendzimir 20-roller cold rolling mill with a working roll diameter of 20 mm to produce TA15 foil; the reduction amount in each pass is between 20% and 50%, and the reduction amount decreases as the TA15 foil becomes thinner. The cold-rolled TA15 foil is subjected to vacuum annealing heat treatment with a vacuum degree of 10 -3 -10 -5 Pa, annealing temperature is 500-650°C, and annealing time is 2-6h.

[0055] The TA15 foil after annealing and surface pickling is straightened, striped and packaged. Specifically: After annealing, TA15 foil may have some minor shape defects, such as wavy, curved, etc. By applying a certain tensile force through straightening, the foil will produce plastic deformation in the length direction, thereby eliminating these shape defects and making the foil smoother.

[0056] The straightened TA15 foil is divided into strips to meet the width requirements of different users or different products. The stripped TA15 foil is packaged to prevent the foil from being polluted, scratched, oxidized, etc. by the external environment during transportation and storage, ensuring that the quality of the foil still meets the requirements when it reaches the user. The packaging method can be wrapping packaging, vacuum packaging, etc. Wrapping packaging is to wrap the foil with plastic film and other materials to isolate the air and protect the surface. Vacuum packaging is to put the foil in a vacuum bag, evacuate the air and seal it, which can better prevent oxidation.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing TA15 foil, characterized in that: The following steps are involved: Determine the alloy element ratio according to the target composition range of the TA15 titanium alloy ingot, and determine the smelting raw materials according to the alloy element ratio; perform vacuum electromagnetic suspension smelting on the smelting raw materials to prepare a TA15 titanium alloy ingot, wherein the TA15 titanium alloy ingot has a diameter of 200-240 mm and a mass of 50-100 kg; Forging the TA15 titanium alloy ingot to prepare a hot-rolled slab; hot rolling the hot-rolled slab to prepare a cold-rolled slab; The cold-rolled slab is cold-rolled to prepare a TA15 foil; the thickness of the TA15 foil is 0.05-0.08 mm, the thickness error is ±0.005 mm, and the width of the TA15 foil is ≤350 mm, and the width deviation is ±1 mm.

2. The method for preparing the TA15 foil according to claim 1, characterized in that: The steps of determining alloy element ratio values ​​according to the target composition range of the TA15 titanium alloy ingot and determining smelting raw materials according to the alloy element ratio values ​​include: The target composition range is Al: 5.5-7.1; V: 0.8-2.5; Zr: 1.5-2.5; Mo: 0.5-2.0; based on the target composition range, the alloy element ratio is determined to be Al: 6.5; V: 1.5; Zr: 2.0; Mo: 1.0; based on the alloy element ratio, the smelting raw materials are determined to be titanium sheets, vanadium blocks, molybdenum blocks, zirconium blocks and aluminum sheets.

3. The method for preparing the TA15 foil according to claim 2, characterized in that: The step of performing vacuum electromagnetic suspension smelting on the smelting raw material comprises: The smelting raw materials are placed in a water-cooled crucible of a vacuum electromagnetic levitation furnace according to the melting points and shapes of the smelting raw materials, and vacuum electromagnetic levitation smelting is performed on the smelting raw materials in the water-cooled crucible.

4. The method for preparing the TA15 foil according to claim 3, characterized in that: The step of performing vacuum electromagnetic suspension melting on the smelting raw material in the water-cooled crucible comprises: The smelting raw material is smelted once, the smelting current is 300-1100A, and the cooling time is 90min-120min to prepare a primary ingot; The primary ingot is reversed and subjected to secondary smelting, wherein the smelting current setting value is the same as that of the primary smelting, so as to prepare the secondary ingot; The secondary ingot is reversed and smelted three times, and the smelting current setting value is the same as that of the primary smelting to prepare a TA15 titanium alloy ingot.

5. The method for preparing the TA15 foil according to claim 1, characterized in that: The step of forging the TA15 titanium alloy ingot to prepare a hot-rolled slab comprises: The TA15 titanium alloy ingot is heated to 750-780°C, kept warm for 100-120 minutes, then heated to 980-1050°C at a heating rate of 10-15°C / min, and kept warm for 120-150 minutes; and then free forging is performed to prepare a hot-rolled slab with a thickness of 50-80 mm and a width of 280-300 mm.

6. The method for preparing the TA15 foil according to claim 1, characterized in that: The step of hot-rolling the hot-rolled slab to prepare a cold-rolled slab comprises: The hot-rolled slab is heated to 900-950°C for hot rolling to prepare the cold-rolled slab with a thickness of 1-1.5 mm; the holding time is 40-60 minutes, and the final rolling temperature is not less than 800°C; the reduction amount in each pass is 5%-10%; as the thickness of the cold-rolled slab decreases, the reduction amount decreases.

7. The method for preparing the TA15 foil according to claim 6, characterized in that: The step of hot rolling the hot-rolled slab to prepare a cold-rolled slab further comprises: During the hot rolling process, the cold-rolled slab is subjected to intermediate annealing, the number of annealing is 1-2 times, the annealing temperature is 750-850° C., and the annealing time is 40-60 minutes.

8. The method for preparing the TA15 foil according to claim 7, characterized in that: After the step of hot-rolling the hot-rolled slab to prepare a cold-rolled slab, the method further comprises: The cold-rolled slab is pickled at a temperature of 30-50° C. for 5-15 minutes using a mixed solution of 10%-15% nitric acid and 1%-3% hydrofluoric acid.

9. The method for preparing the TA15 foil according to any one of claims 1 to 8, characterized in that: The step of cold rolling the cold-rolled slab to prepare a TA15 foil comprises: The cold-rolled slab is cold-rolled by a twenty-roll cold rolling mill with a working roll diameter of 20 mm-30 mm to prepare a TA15 foil; the reduction amount in each pass is between 20% and 50%, and the reduction amount decreases as the TA15 foil becomes thinner.

10. The method for preparing the TA15 foil according to claim 9, characterized in that: After the step of cold rolling the cold-rolled slab, the method further comprises: The cold-rolled TA15 foil is subjected to vacuum annealing heat treatment, the annealing temperature is 500-650° C., and the annealing time is 2-6 hours.

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