Preparation method of titanium-copper alloy plate or strip

Abstract

The invention relates to the technical field of titanium and titanium alloy processing, in particular to a preparation method of a titanium-copper alloy plate or strip, which comprises the following steps: selecting a Ti-5Cu alloy casting blank with the thickness of 60-200mm, the width of 600-2000mm and the length of Lmm; analyzing and measuring the phase transition temperature T1 of the Ti-5Cu alloy casting blank; the method comprises the following steps: coating the surface of a Ti-5Cu alloy casting blank with pure titanium or coating the surface of the Ti-5Cu alloy casting blank with an anti-oxidation coating to obtain an anti-oxidation blank, heating the anti-oxidation blank to T2 = T1 + (25-160) DEG C, and keeping the temperature for 10-60 minutes; carrying out hot rolling on the antioxidant blank subjected to heating and heat preservation at the temperature not lower than 700 DEG C; and the hot-rolled blank is subjected to cold rolling, and the titanium-copper alloy plate or strip with the thickness being 0.2-3 mm is obtained. The hot rolling process is carried out in the interval above the phase transition temperature of the Ti-5Cu alloy, it is avoided that when beta-phase region machining is finished, coarse grains are reserved in metal, and in the cold rolling process, rolling defects caused by work hardening and strip cold rolling are eliminated through vacuum annealing or protective atmosphere annealing, the alloy machining plasticity is recovered, and the strip cold rolling machining performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium and titanium alloy processing, and relates to a preparation method of titanium-copper alloy plate or strip Method. BACKGROUND

[0002] Ti-Cu alloy is a titanium alloy with high specific strength, high corrosion resistance and biocompatibility. The alloy has phase transition during the heating process. During the heating process, titanium is easily affected by oxygen, nitrogen, hydrogen, water vapor, carbon dioxide and metal oxides in the environment, resulting in oxygen absorption, nitrogen absorption, hydrogen increase, iron increase and silicon increase of the alloy. Due to the high-temperature metallurgical characteristics of titanium alloy, the content of impurities such as iron, oxygen and hydrogen in the alloy is relatively high. Since part of the iron, oxygen, nitrogen and hydrogen exist in the form of coarse metal compounds in the titanium alloy matrix, the metallurgical defects of the alloy matrix are increased, and the strength and corrosion resistance of the alloy are reduced.

[0003] At present, the main problems existing in the processing of Ti-Cu alloy plate are as follows: 1. The phase transition temperature of Ti-Cu alloy is not easy to determine and control. When the hot working temperature is lower than the phase transition temperature, the metal plasticity is low, the processing process is easy to crack, and the deformation resistance is large, which not only reduces the product quality and yield of the plate, but also increases the roller consumption and production cost. 2. When Ti-Cu alloy is rolled at high temperature, the metal is oxidized and nitrided to reduce the plasticity of the product, the Ti2Cu is precipitated in large amount during the hot working process, resulting in strength loss and unsatisfactory final heat treatment effect, and the final mechanical properties and corrosion resistance of the product are difficult to meet the requirements of the user; the coarse metal compound inclusions not only affect the performance of the product, but also are the source of crack initiation and propagation, which is an important reason for the failure of the structure, reduces the corrosion resistance of the alloy and shortens the service life of the device.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] The present application aims at overcoming the defects of the prior art and providing a preparation method of titanium-copper alloy plate or strip.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: The present application provides a preparation method of titanium-copper alloy plate or strip, comprising the following steps: Step 1: selecting Ti-5Cu alloy cast blank with a thickness of 60-200mm, a width of 600-2000mm and a length of Lmm for standby; Step 2: analyzing and determining the phase transition temperature T1 of the Ti-5Cu alloy cast blank in step 1; ​Step 3: The surface of the Ti-5Cu alloy casting blank is coated with pure titanium or coated with an oxidation-resistant coating to obtain an oxidation-resistant blank, and finally, the oxidation-resistant blank is heated to T2 = T1 + (25-160) °C and kept for 10-60 min; Step 4: The oxidation-resistant blank after heating and keeping in Step 3 is hot-rolled at a temperature not lower than 700 °C to obtain a hot-rolled blank with a thickness of 1-30 mm; Step 5: The hot-rolled blank obtained in Step 4 is cold-rolled to obtain a titanium-copper alloy plate or strip with a thickness of 0.2-3 mm.

[0007] Further, in Step 1, the Ti-5Cu alloy casting blank is a Ti-5Cu alloy casting slab ingot prepared by melting and casting using EB electron beam furnace or plasma technology, with titanium content ≥ 99.5% and (Cu+Ag) content ≥ 99.95% of standard cathode copper or Cu content ≥ 99.9935% of high-purity cathode copper as raw materials. EB electron beam cold bed furnace is used for Ti-5Cu alloy melting, and high-energy electron beam high temperature melting and dissolving high-density and low-density inclusions in the Ti-5Cu alloy. Inclusions that cannot be melted and dissolved are removed by floating and sedimentation mechanism and solidified in the cold hearth of the condensate, to obtain pure, uniform temperature and composition Ti-5Cu alloy liquid, which is cooled and solidified into Ti-5Cu alloy slab ingot through a casting mold.

[0008] Moreover, the length L of the Ti-5Cu alloy casting blank is determined by the rolling mill parameters and product delivery requirements.

[0009] Further, the segregation amount of Cu in the Ti-5Cu alloy casting slab ingot is less than 0.2%. Specifically, referring to Figure 2 As shown in the drawing, the present application takes chemical composition analysis, metallographic analysis, phase transition temperature analysis and mechanical property analysis samples from A, B, C, D and E parts of the Ti-5Cu alloy casting ingot melted and cast by the electron beam furnace or plasma technology. Inductively coupled plasma atomic emission spectrometer or inductively coupled plasma mass spectrometer, OM, SEM and universal material tensile testing machine are used to test and analyze the chemical composition, casting structure and mechanical properties of the casting slab ingot, analyze the distribution and segregation of Cu element in each part of the casting ingot, analyze the differences in structure and mechanical properties of each part of the casting ingot, and evaluate the quality of the casting ingot; the batching, melting, casting process and mold cooling structure are improved according to the evaluation results; the Ti-5Cu alloy casting slab ingot is prepared, melted and cast again according to the improved process and mold, and the composition, structure and mechanical properties of the casting ingot are evaluated again, and the batching, melting, casting process and mold cooling structure are continuously improved and optimized according to the evaluation results, until the Ti-5Cu alloy casting slab ingot with Cu segregation less than 0.2% and uniform metallographic structure and mechanical properties is obtained.

[0010] Further, the phase transition temperature T1 of the Ti-5Cu alloy casting blank is determined by metallographic analysis, thermal expansion analysis, DTA differential thermal analysis or DSC differential scanning calorimetry, and the temperature base point of the Ti-5Cu alloy hot rolling is determined according to the phase transition temperature.

[0011] Further, in step 3, the surface of the Ti-5Cu alloy casting blank is coated with pure titanium to improve the process plasticity of the alloy. In order to prevent the Ti-5Cu alloy casting blank from being oxidized, nitrided and gassed at high temperature, the anti-oxidation coating is composed of the following components by mass fraction: SiO2: 32-39%; B2O3: 7-10%; Na2O: 26-36%; TiO2: 22-28%.

[0012] Further, in step 3, the heating includes two stages, i.e. a low-temperature rapid heating stage and a high-temperature slow heating stage, which can reduce the temperature difference of the casting blank core and reduce the ingot temperature difference stress, shorten the ingot heating time, and reduce the pollution of the atmosphere to the ingot oxidation. The heating and holding time is controlled within 150 min.

[0013] Further, in step 4, the hot rolling is carried out by using a four-high reversible hot rolling mill. The hot rolling is divided into one-pass hot rolling or two-pass hot rolling, and the total deformation amount of each pass hot rolling is not more than 95%, and the pass deformation amount is not more than 26%. When the rolling deformation amount reaches 40-60%, the rolling needs to be reversed, and 1-3 passes are rolled along the longitudinal direction of the ingot, and 4-8 passes are rolled along the transverse direction of the blank.

[0014] Further, in step 4, the obtained hot-rolled blank needs to be quickly cooled, and the surface oxide slag layer is removed. After annealing at not less than 700℃ for 30 min, cold rolling is carried out.

[0015] Further, the cold rolling is carried out by using a six-high cold rolling mill. After each one to two rolling pass, annealing treatment is carried out once. The annealing treatment process is cooling to not less than 700℃, holding for 30 min, and then air cooling. Each time after annealing, the blank needs to be subjected to an alkaline washing and an acid washing process. The alkaline washing process includes: the alkaline washing liquid is 80% NaOH+20% NaNO3, the alkaline washing temperature is 45-50℃, and the alkaline washing time is 10-20 min. The acid washing process includes: the acid washing liquid is 6% HF+20-25% HNO3, and the rest is water, and the acid washing time is 10-20 min. The pass deformation amount of each rolling pass is controlled within 40-45%.

[0016] Furthermore, after the cold rolling is completed, the obtained cold-rolled billet is surface cleaned, the oxide slag layer is removed, and then annealed under vacuum or argon protective atmosphere to obtain titanium-copper alloy plates or strips.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention uses high-quality sponge titanium, standard electrolytic copper, or high-purity electrolytic copper as raw materials. It employs an EB electron beam cold bed melting process to form high-quality Ti-5Cu alloy casting ingots in a single process. An argon or helium protective atmosphere is used to reduce Cu element volatilization and burn-off during melting, simplifying the production process and lowering production costs. The hot rolling process is carried out above the Ti-5Cu alloy phase transformation temperature. Utilizing the alloy's low deformation resistance and good plasticity during β-phase rolling, the alloy is rolled to ensure that the deformation in the β-phase region reaches 40%-85%, avoiding the retention of coarse grains in the metal at the end of β-phase processing. The cold rolling process is carried out on a 6-roll cold rolling mill. Vacuum annealing or protective atmosphere annealing eliminates work hardening and rolling defects caused by cold rolling of the strip, restoring the alloy's processing plasticity and improving the cold rolling performance of the strip. Attached Figure Description

[0018] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This invention provides a flowchart of a method for preparing titanium-copper alloy plates or strips; Figure 2 This is a schematic diagram of the sampling location for the Ti-5Cu alloy ingot according to the present invention. Detailed Implementation

[0021] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0022] This invention provides a method for preparing titanium-copper alloy plates or strips, see below. Figure 1 As shown, it includes the following steps: Step 1: Select a Ti-5Cu alloy billet with a thickness of 60~200mm × width of 600~2000mm × length of Lmm, and set it aside.

[0023] Specifically, the Ti-5Cu alloy ingot provided by this invention is a Ti-5Cu alloy casting ingot made by melting and casting sponge titanium with a titanium content ≥99.5% and standard cathode copper with a (Cu+Ag) content ≥99.95% or high-purity cathode copper with a Cu content ≥99.9935% using EB electron beam furnace or plasma technology. The Ti-5Cu alloy is melted in an EB electron beam cold hearth furnace. High-energy electron beams melt and dissolve high-density and low-density inclusions in the Ti-5Cu alloy at high temperatures. Inclusions that cannot be melted or dissolved are solidified in the solidified shell of the cold hearth through flotation and sedimentation mechanisms, resulting in a pure Ti-5Cu alloy liquid with uniform temperature and composition. This liquid is then cooled and solidified in a mold to form a Ti-5Cu alloy ingot. Furthermore, the length L of the Ti-5Cu alloy ingot is determined by the rolling mill parameters and product supply requirements.

[0024] Furthermore, the Cu segregation in the Ti-5Cu alloy casting ingot provided by this invention is less than 0.2%. Specifically, see... Figure 2 As shown, the present invention takes samples from parts A, B, C, D and E of Ti-5Cu alloy ingots melted and cast by electron beam furnace or plasma technology for chemical composition analysis, metallographic analysis, phase transformation temperature analysis and mechanical property analysis, respectively. The chemical composition, casting structure, and mechanical properties of the cast ingots were analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS), OM, SEM, and a universal tensile testing machine. The distribution and segregation of Cu in different parts of the ingot were analyzed, as well as the differences in microstructure and mechanical properties between different parts, to evaluate the ingot quality. Based on the evaluation results, the batching, smelting, casting processes, and mold cooling structure were improved. Based on the improved processes and molds, Ti-5Cu alloy cast ingots were re-formulated, smelted, and cast, and the composition, microstructure, and mechanical properties of the ingots were evaluated a second time. Based on the evaluation results, the batching, smelting, casting processes, and mold cooling structure were continuously improved and optimized until a Ti-5Cu alloy cast ingot with Cu segregation of less than 0.2% and uniform microstructure and mechanical properties was obtained for use.

[0025] Step 2: Analyze and determine the phase transformation temperature T1 of the Ti-5Cu alloy billet in Step 1.

[0026] Specifically, metallographic analysis, thermal expansion analysis, DTA differential thermal analysis, or DSC differential scanning calorimetry are used to analyze and determine the phase transformation temperature T1 of the Ti-5Cu alloy billet, and the temperature base point for hot rolling of Ti-5Cu alloy is determined based on the phase transformation temperature.

[0027] Step 3: Coat the surface of Ti-5Cu alloy billet with pure titanium or coat the surface of Ti-5Cu alloy billet with an anti-oxidation coating to obtain an anti-oxidation billet. Finally, heat the anti-oxidation billet to T2=T1+(25~160)℃ and hold for 10~60min.

[0028] Specifically, firstly, before hot rolling the Ti-5Cu alloy billet of the present invention, the surface of the Ti-5Cu alloy billet is coated with pure titanium to obtain a titanium billet. The purpose of this is to improve the plasticity of the alloy process and to prevent oxidation, nitriding, and gas absorption of the Ti-5Cu alloy billet at high temperatures.

[0029] Next, an anti-oxidation coating is applied to the surface of the titanium billet. The anti-oxidation coating consists of the following components by mass fraction: SiO2: 32~39%; B2O3: 7~10%; Na2O: 26~36%; TiO2: 22~28%.

[0030] Finally, the coated titanium billet is heated to T2 = T1 + (25~160)℃ and held for 10~60 minutes, completing the hot rolling in one or two passes. A two-stage ingot heating process is used: rapid heating at low temperature and slow, uniform heating at high temperature. This reduces the temperature difference between the billet core and surface, decreases ingot thermal stress, shortens the ingot heating time, and reduces atmospheric contamination of the ingot. The total heating-holding time is controlled within 150 minutes.

[0031] Specifically, the heating process for the rapid heating stage at low temperatures is as follows: rapid heating is carried out at a heating rate of 10~15℃ / min between room temperature and 700℃; the heating process for slow uniform heating at high temperatures is as follows: slow uniform heating is carried out at a heating rate of 2~5℃ / min between 700℃ and T2℃.

[0032] Step 4: The titanium billet after being heated and kept warm in Step 3 is hot rolled at a temperature of not less than 700°C to obtain a hot-rolled billet with a thickness of 1~30mm.

[0033] Specifically, hot rolling is performed using a four-roll reversible hot rolling mill. The hot rolling is performed in one or two passes, with the total deformation in each pass not exceeding 95% and the deformation per pass not exceeding 26%. When the deformation reaches 40-60%, reversing rolling is required. Passes 1-3 are rolled longitudinally along the ingot, and passes 4-8 are rolled transversely along the billet. The resulting hot-rolled billet needs to be rapidly cooled to remove the surface oxide layer, i.e., annealed to at least 700°C and held for 30 minutes before cold rolling.

[0034] Step 5: Cold roll the hot-rolled billet obtained in Step 4 to obtain titanium-copper alloy plates or strips with a thickness of 0.2~3mm.

[0035] Specifically, the cold rolling is carried out using a six-roll cold rolling mill. After each or two rolling passes, an annealing process is performed. The annealing process involves cooling to 790°C, holding at that temperature for 30 minutes, and then air cooling.

[0036] Each annealed billet needs to undergo an alkaline washing and acid washing process. The alkaline washing process includes: the alkaline washing solution is 80% NaOH + 20% NaNO3, the alkaline washing temperature is 45~50℃, and the alkaline washing time is 10~20min. The acid washing process includes: the acid washing solution is 6% HF + 20~25% HNO3, with the remainder being water, and the acid washing time is 10~20min. The deformation amount of each rolling pass is controlled at 40~45%.

[0037] After cold rolling, the obtained cold-rolled billet is cleaned on the surface and the oxide slag layer is removed. Then, it is annealed in a vacuum or argon protective atmosphere to obtain titanium-copper alloy plates or strips. The annealing process here is furnace cooling to room temperature, and then it is inspected and put into storage.

[0038] To verify the beneficial effects of the preparation method of the present invention, the following examples are provided for further explanation.

[0039] Example 1 This embodiment provides a method for preparing a 3mm thick Ti-5Cu alloy cold-rolled finished sheet, including the following steps: A slab with a thickness of 200mm × width of 2000mm × length of 2200mm was cast. A 30mm thick Ti-5Cu alloy hot-rolled sheet was prepared using a single-pass rolling process. The hot-rolled sheet was then cold-rolled to prepare a 3mm thick cold-rolled sheet. The specific steps are as follows: Step 1: Using sponge titanium with a titanium content of ≥99.5% and standard cathode copper with (Cu+Ag) ≥99.95% or high-purity cathode copper with Cu ≥99.9935 as raw materials, melt and cast a Ti-5Cu alloy billet with a thickness of 200mm × width of 2000mm × length of 2200mm on an EB electron beam furnace. Remove inclusions, oxide scale and nitride scale defects from the surface of the billet and set it aside for use. Step 2: The phase transformation temperature T1 of the Ti-5Cu alloy billet was determined using the thermal expansion method, which was 810.5℃.

[0040] Step 3: Coat the surface of Ti-5Cu alloy billet with 0.25mm thick industrial pure titanium to obtain an anti-oxidation billet. Heat the anti-oxidation billet to T2=T1+144.5℃=955℃ and hold at 955℃ for 60min.

[0041] Step 4: The antioxidant billet after heating and heat preservation in step 3 is hot rolled at a temperature of not less than 700℃ to obtain a hot-rolled billet with a thickness of 30mm.

[0042] The specific process is as follows: The single-pass rolling process is adopted, with a total rolling deformation of approximately 85.0%. The number of rolling passes is as follows: Specific deformation amounts per pass: 200.00mm → 150.00mm (25.0% deformation) → 114.00mm (24.0% deformation) → 86.60mm (24.04% deformation) → 66.60mm (23.09% deformation) → 51.10mm (23.90% deformation) → 38.90mm (23.88% deformation) → 30.00mm (22.88% deformation).

[0043] The final rolling temperature in the first pass was 841℃, the total deformation was 85%, and the maximum deformation per pass was 25.0%. When the rolling deformation reaches 40%-50%, reversing rolling is required. Rolling is performed in 1-3 passes along the longitudinal direction of the ingot and in 4-7 passes along the transverse direction of the billet. For ultra-long billets, it is necessary to interrupt the rolling process before transverse rolling. After rolling is completed, the hot-rolled billet needs to be annealed before cold rolling. The billet is annealed to 790°C, the surface oxide slag layer is removed, and it is held at 790°C for 30 minutes.

[0044] Step 5: Cold roll the 30mm thick hot-rolled billet obtained in Step 4 to obtain a 3mm thick Ti-5Cu alloy cold-rolled finished sheet.

[0045] The cold rolling process is as follows: Specific deformation amounts per pass: 30.00mm → 22.50mm (25.0% deformation per pass) → 17.10mm (24.00% deformation per pass) → Annealing (790℃, 30min, air cooling) → Alkali washing, pickling → 12.80mm (25.15% deformation per pass) → 9.60mm (25.00% deformation per pass) → Annealing → Alkali washing, pickling → 7.20mm (25.00% deformation per pass) → 5.40mm (25.00% deformation per pass) → Annealing → Alkali washing, pickling → 4.05mm (25.00% deformation per pass) → 3.00mm (24.70% deformation per pass).

[0046] After each or two cold rolling passes, an annealing process is performed. The annealing process involves air cooling at 790℃ for 30 minutes. The annealed billet is then subjected to alkaline washing and acid washing. The washing process includes: alkaline washing solution of 80% NaOH + 20% NaNO3 at a temperature of 45-50℃; and acid washing solution of 6% HF + 20-25% HNO3, with the remainder being water. The deformation amount in each rolling pass is controlled at 40%-45%.

[0047] Finally, the cold-rolled slab is cleaned, the oxide slag layer is removed, and it is annealed to room temperature under a vacuum or argon protective atmosphere before being inspected and put into storage.

[0048] Example 2 This embodiment provides a method for preparing a cold-rolled Ti-5Cu alloy sheet with a thickness of 1 mm, including the following steps: A slab with a thickness of 150mm × width of 1800mm × length of 2500mm was cast. A 15mm thick Ti-5Cu alloy hot-rolled sheet was prepared using a single-pass rolling process. The hot-rolled sheet was then cold-rolled to prepare a 1mm thick cold-rolled sheet. The specific steps are as follows: Step 1: Using 99.83% sponge titanium and 99.9945% high-purity copper as raw materials, a Ti-5Cu alloy billet with a thickness of 150mm × width of 1800mm × length of 2500mm is melted and cast using plasma technology. The billet is of excellent quality and has qualified chemical composition. Inclusions, oxide scale and nitride scale defects on the surface of the billet are removed and it is ready for use. Step 2: Metallographic analysis was used to determine the phase transformation temperature T1 of the Ti-5Cu alloy billet, which was 809.3℃.

[0049] Step 3: Coat the surface of Ti-5Cu alloy billet with 0.3mm thick industrial pure titanium to obtain an anti-oxidation billet. Heat the anti-oxidation billet to T2=T1+140.7℃=950℃ and hold at 950℃ for 40min.

[0050] Step 4: The antioxidant billet after heating and heat preservation in step 3 is hot rolled at a temperature of not less than 700℃ to obtain a hot-rolled billet with a thickness of 15mm.

[0051] The specific process is as follows: The single-pass rolling process is adopted, with a total rolling deformation of approximately 86.67% and a maximum deformation of 25.3% per pass. The rolling passes are as follows: Specific deformation amounts per pass: 150.00mm → 112.00mm (25.3% deformation) → 84.10mm (24.91% deformation) → 63.10mm (24.97% deformation) → 47.30mm (25.03% deformation) → 35.40mm (25.15% deformation) → 26.60mm (24.85% deformation) → 19.95mm (25.00% deformation) → 15.00mm (24.81% deformation).

[0052] The final rolling temperature in the first pass was 828℃, the total deformation was 86.67%, and the maximum deformation per pass was 25.3%. When the rolling deformation reaches 50%-60%, reversing rolling is required. Rolling is performed in the longitudinal direction of the ingot for 1-4 passes and in the transverse direction of the billet for 5-8 passes. For ultra-long billets, the rolling process needs to be interrupted before transverse rolling. After rolling is completed, the hot-rolled billet needs to be annealed before cold rolling. The billet is annealed to 805℃, the surface oxide slag layer is removed, and it is held at 805℃ for 25 minutes.

[0053] Step 5: Cold roll the 15mm thick hot-rolled billet obtained in Step 4 to obtain a 3mm thick Ti-5Cu alloy cold-rolled finished sheet.

[0054] The cold rolling process is as follows: Specific deformation amounts per pass: 15.00mm → 11.25mm (25.0% deformation per pass) → 8.44mm (24.98% deformation per pass) → Annealing (805℃, 25min, air cooling) → Alkali washing, pickling → 6.33mm (25.00% deformation per pass) → 4.75mm (24.96% deformation per pass) → Annealing → Alkali washing, pickling → 3.57mm (24.84% deformation per pass) → 2.68mm (24.93% deformation per pass) → Annealing → Alkali washing, pickling → 2.01mm (25.00% deformation per pass) → 1.51mm (24.88% deformation per pass) → Annealing → Alkali washing, pickling → 1.20mm (20.53% deformation per pass) → 1.00mm (16.67% deformation per pass).

[0055] After each or two cold rolling passes, an annealing process is performed. The annealing process involves air cooling at 805℃ for 25 minutes. The annealed billet is then subjected to alkaline washing and acid washing. The washing process includes: alkaline washing solution of 80% NaOH + 20% NaNO3 at a temperature of 45-50℃; and acid washing solution of 6% HF + 20-25% HNO3, with the remainder being water. The deformation amount in each rolling pass is controlled at 40%-45%.

[0056] Finally, the cold-rolled slab is cleaned, the oxide slag layer is removed, and it is annealed to room temperature under a vacuum or argon protective atmosphere before being inspected and put into storage.

[0057] Example 3 This embodiment provides a method for preparing a cold-rolled Ti-5Cu alloy strip with a thickness of 0.5 mm, including the following steps: A slab with a thickness of 80mm × width of 2000mm × length of 2000mm was cast. A 2.6mm thick Ti-5Cu alloy hot-rolled coil was prepared using a two-stage rolling process. The hot-rolled coil was then cold-rolled to produce a 0.5mm thick cold-rolled sheet. The specific steps are as follows: Step 1: Using 99.98% sponge titanium and 99.9953% high-purity copper as raw materials, a Ti-5Cu alloy billet with a thickness of 80mm × width of 2000mm × length of 2000mm is melted and cast using EB electron beam furnace technology. The billet is of excellent quality and has qualified chemical composition. Inclusions, oxide scale and nitride scale defects on the surface of the billet are removed and it is ready for use. Step 2: The phase transformation temperature T1 of the Ti-5Cu alloy billet was determined to be 811.3℃ using DTA differential thermal analysis.

[0058] Step 3: Coat the surface of the Ti-5Cu alloy billet with an anti-oxidation coating to obtain an anti-oxidation billet. The anti-oxidation coating components are: SiO2: 33%, B2O3: 12%; Na2O: 31%; TiO2: 24%. Heat the anti-oxidation billet to T2 = T1 + 148.7℃ = 960℃ and hold at 960℃ for 20 minutes.

[0059] Step 4: The antioxidant billet after heating and heat preservation in step 3 is hot rolled at a temperature of not less than 700℃ to obtain a hot-rolled billet with a thickness of 2.6mm.

[0060] The specific process is as follows: The two-stage hot rolling process is adopted, with the total deformation of the single-stage hot rolling being approximately 81.88%. Specific deformation amounts per pass: 80.00mm → 60.00mm (25.0% deformation) → 45.00mm (25.00% deformation) → 33.75mm (25.0% deformation) → 25.32mm (24.98% deformation) → 18.99mm (25.00% deformation) → 14.50mm (23.64% deformation). The final rolling temperature of the first rolling pass is 825.6℃. When the rolling deformation reaches 45%-60%, the reversing rolling is carried out. The first 1-3 passes are rolled transversely along the ingot, and the 4th-6th passes are rolled longitudinally along the billet. For extra-long billets, the rolling process needs to be interrupted before transverse rolling. After rolling is completed, the billet is rapidly cooled to 750℃ and the surface oxide slag layer is removed.

[0061] The total deformation during the second hot rolling process was 82.76%. The second hot rolling process is heated to 950℃ and held for 15 minutes. The specific deformation amounts for each pass are as follows: 14.50mm → 10.90mm (24.83% deformation) → 8.18mm (24.95% deformation) → 6.14mm (24.94% deformation) → 4.61mm (24.92% deformation) → 3.45mm (24.94% deformation) → 2.60mm (24.64% deformation). The total deformation in the second rolling pass was 82.76%, with a maximum deformation of 24.95% per pass. The second rolling temperature is 819℃. After rolling, the billet is annealed to a heating temperature of 750℃ and held at 750℃ for 45 minutes. The surface oxide slag layer is removed to obtain a hot-rolled coil.

[0062] Step 5: The 2.6mm thick hot-rolled coil obtained in Step 4 is cold-rolled to obtain a 0.5mm thick Ti-5Cu alloy cold-rolled finished strip.

[0063] The cold rolling process is as follows: Specific deformation amounts per pass: 2.60mm → 1.95mm (25.0% deformation per pass) → 1.47mm (24.62% deformation per pass) → Annealing (750℃, 45min, air cooling) → Alkali washing, pickling → 1.10mm (25.17% deformation per pass) → 0.83mm (24.54% deformation per pass) → 0.63mm (24.10% deformation per pass) → Annealing → Alkali washing, pickling → 0.50mm (20.64% deformation per pass).

[0064] After each or two cold rolling passes, an annealing process is performed. The annealing process involves air cooling at 750℃ for 45 minutes. The annealed billet is then subjected to alkaline washing and acid washing. The washing process includes: the alkaline washing solution is 80% NaOH + 20% NaNO3, the alkaline washing temperature is 45-50℃, and the acid washing solution is 6% HF + 20~25% HNO3, with the remainder being water. The deformation amount in each rolling pass is controlled at 40%-45%.

[0065] Finally, the cold-rolled strip undergoes surface cleaning, removal of oxide slag layer, annealing to room temperature under vacuum or argon protective atmosphere, and then inspection and warehousing.

[0066] Example 4 This embodiment provides a method for preparing a cold-rolled Ti-5Cu alloy strip with a thickness of 0.2 mm, comprising the following steps: A slab with a thickness of 60mm × width of 1000mm × length of 1800mm was cast. A 1.0mm thick Ti-5Cu alloy hot-rolled coil was prepared using a two-stage rolling process. The hot-rolled coil was then cold-rolled to produce a 0.2mm thick cold-rolled sheet. The specific steps are as follows: Step 1: Using 99.96% sponge titanium and 99.9965% high-purity copper as raw materials, a Ti-5Cu alloy billet with a thickness of 60mm × width of 1000mm × length of 1800mm is melted and cast using plasma technology. The billet is of excellent quality and has qualified chemical composition. Inclusions, oxide scale and nitride scale defects on the surface of the billet are removed and it is ready for use. Step 2: The phase transformation temperature T1 of the Ti-5Cu alloy billet was determined to be 807.3℃ using differential scanning calorimetry (DSC).

[0067] Step 3: Coat the surface of the Ti-5Cu alloy billet with an anti-oxidation coating to obtain an anti-oxidation billet. The anti-oxidation coating composition is: SiO2: 39%, B2O3: 6%; Na2O: 28%; TiO2: 27%. Heat the anti-oxidation billet to T2 = T1 + 152.7℃ = 960℃ and hold at 960℃ for 15 minutes.

[0068] Step 4: The antioxidant billet after heating and heat preservation in step 3 is hot rolled at a temperature of not less than 700℃ to obtain a hot-rolled billet with a thickness of 2.6mm.

[0069] The specific process is as follows: The two-stage hot rolling process is adopted, and the total deformation of the single-stage hot rolling is about 89.17%. Specific deformation amounts per pass: 60.00mm (25.0% deformation) → 45.00mm (25.00% deformation) → 33.75mm (25.0% deformation) → 25.32mm (24.98% deformation) → 18.99mm (25.00% deformation) → 14.50mm (23.64% deformation) → 10.90mm (24.83% deformation) → 8.18mm (24.95% deformation) → 6.50mm (20.54% deformation).

[0070] The final rolling temperature of the first rolling pass is 837℃. When the rolling deformation reaches 50%-58%, the reversing rolling is carried out. The first 1-3 passes are rolled transversely along the ingot, and the 4th-8th passes are rolled longitudinally along the billet. For extra-long billets, the rolling process needs to be interrupted before transverse rolling. After rolling is completed, the billet is rapidly cooled to 745℃ and the surface oxide slag layer is removed.

[0071] The total deformation in the second hot rolling process was 84.62%, with a maximum deformation of 25.0% per pass. The second hot rolling process involves a heating temperature of 950℃ and a holding time of 15 minutes. The specific deformation amounts for each pass are as follows: 6.50mm → 4.87mm (25.08% deformation) → 3.66mm (24.84% deformation) → 2.75mm (24.86% deformation) → 2.07mm (24.73% deformation) → 1.56mm (25.00% deformation) → 1.20mm (23.1% deformation) → 1.00mm (16.67% deformation). The second rolling temperature is 822℃. After rolling, the billet is annealed to a heating temperature of 745℃ and held at 745℃ for 39 minutes. The surface oxide slag layer is removed to obtain a hot-rolled coil.

[0072] Step 5: The hot-rolled coil with a thickness of 1.0 mm obtained in Step 4 is cold-rolled to obtain a Ti-5Cu alloy cold-rolled finished strip with a thickness of 0.2 mm.

[0073] The cold rolling process is as follows: Specific deformation per pass: 1.00mm → 0.75mm (25.0% deformation per pass) → 0.57mm (24.0% deformation per pass) → Annealing → Alkali washing, pickling → 0.43mm (24.56% deformation per pass) → 0.33mm (23.26% deformation per pass) → Annealing → Alkali washing, pickling → 0.25mm (24.24% deformation per pass) → 0.20mm (20.0% deformation per pass).

[0074] After each or two cold rolling passes, an annealing process is performed. The annealing process involves air cooling at 745℃ for 39 minutes. The annealed billet is then subjected to alkaline washing and acid washing. The washing process includes: the alkaline washing solution is 80% NaOH + 20% NaNO3, the alkaline washing temperature is 45-50℃, and the acid washing solution is 6% HF + 20~25% HNO3, with the remainder being water. The deformation amount in each rolling pass is controlled at 40%-45%.

[0075] Finally, the cold-rolled strip undergoes surface cleaning, removal of oxide slag layer, annealing to room temperature under vacuum or argon protective atmosphere, and then inspection and warehousing.

[0076] As can be seen from the above embodiments, the total deformation of each hot rolling pass of the present invention does not exceed 95%, the deformation per pass does not exceed 26%, and the final rolling temperature is not lower than 700°C.

[0077] This method uses high-quality sponge titanium, standard electrolytic copper, or high-purity electrolytic copper as raw materials. It employs an EB electron beam cooling bed or plasma technology to melt and form high-quality Ti-5Cu alloy casting ingots in a single process. An argon or helium protective atmosphere is used to reduce Cu element volatilization and burn-off during melting, simplifying the production process and lowering costs. The hot rolling process is carried out above the Ti-5Cu alloy phase transformation temperature. It utilizes the alloy's low deformation resistance and good plasticity during rolling in the β-phase region, ensuring that the deformation in the β-phase region reaches 40%-85%, thus avoiding the retention of coarse grains in the metal at the end of β-phase processing. The cold rolling process is carried out on a 6-roll cold rolling mill. Vacuum annealing or protective atmosphere annealing eliminates work hardening and rolling defects caused by cold rolling of the strip, restoring the alloy's processing plasticity and improving the cold rolling performance of the strip.

[0078] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0079] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing titanium-copper alloy plates or strips, characterized in that, Includes the following steps: Step 1: Select a Ti-5Cu alloy billet with a thickness of 60~200mm × width of 600~2000mm × length of Lmm, and set it aside; Step 2: Analyze and determine the phase transformation temperature T1 of the Ti-5Cu alloy billet described in Step 1; Step 3: Coat the surface of Ti-5Cu alloy billet with pure titanium or coat the surface of Ti-5Cu alloy billet with an anti-oxidation coating to obtain an anti-oxidation billet. Finally, heat the anti-oxidation billet to T2=T1+(25~160)℃ and hold for 10~60min. Step 4: The antioxidant billet after heating and heat preservation in step 3 is hot rolled at a temperature of not less than 700℃ to obtain a hot-rolled billet with a thickness of 1~30mm; Step 5: Cold roll the hot-rolled billet obtained in Step 4 to obtain titanium-copper alloy plates or strips with a thickness of 0.2~3mm.

2. The method for preparing titanium-copper alloy plates or strips according to claim 1, characterized in that, In step 1, the Ti-5Cu alloy billet is a Ti-5Cu alloy casting ingot made by melting and casting sponge titanium with a titanium content ≥99.5% and standard cathode copper with a (Cu+Ag) content ≥99.95% or high-purity cathode copper with a Cu content ≥99.9935% through EB electron beam furnace or plasma technology.

3. The method for preparing titanium-copper alloy plates or strips according to claim 2, characterized in that, The amount of Cu segregation in the Ti-5Cu alloy cast ingot is less than 0.2%.

4. The method for preparing titanium-copper alloy plates or strips according to claim 1, characterized in that, In step 2, metallographic analysis, thermal expansion analysis, DTA differential thermal analysis, or DSC differential scanning calorimetry are used to analyze and determine the phase transformation temperature T1 of the Ti-5Cu alloy billet.

5. The method for preparing titanium-copper alloy plates or strips according to claim 1, characterized in that, In step 3, the antioxidant coating consists of the following components by mass fraction: SiO2: 32~39%; B2O3: 7~10%; Na2O: 26~36%; TiO2: 22~28%.

6. The method for preparing titanium-copper alloy plates or strips according to claim 1, characterized in that, In step 3, the heating includes two stages: a rapid heating stage at low temperature and a slow and even heating stage at high temperature. The heating and heat preservation time is controlled within 150 minutes.

7. The method for preparing titanium-copper alloy plates or strips according to claim 1, characterized in that, In steps 3 and 4, hot rolling is carried out using a four-roll reversible hot rolling mill. The hot rolling is divided into single-pass hot rolling or double-pass hot rolling. The total deformation of each hot rolling pass does not exceed 95%, and the deformation per pass does not exceed 26%. When the deformation reaches 40-60%, reversing rolling is required. Passes 1-3 are rolled along the longitudinal direction of the ingot, and passes 4-8 are rolled along the transverse direction of the billet.

8. The method for preparing titanium-copper alloy plates or strips according to claim 1, characterized in that, In step 4, the obtained hot-rolled billet needs to be rapidly cooled, the surface oxide slag layer is removed, and it is annealed to not less than 700°C and held for 30 minutes before cold rolling.

9. The method for preparing titanium-copper alloy plates or strips according to claim 1, characterized in that, In step 5, the cold rolling is carried out using a six-roll cold rolling mill. After each or two rolling passes, an annealing process is performed. The annealing process involves cooling to a temperature of not less than 700°C, holding at that temperature for 30 minutes, and then air cooling. Each annealed billet needs to undergo an alkaline washing and acid washing process. The alkaline washing process includes: the alkaline washing solution is 80% NaOH + 20% NaNO3, the alkaline washing temperature is 45~50℃, and the alkaline washing time is 10~20min. The acid washing process includes: the acid washing solution is 6% HF + 20~25% HNO3, with the remainder being water, and the acid washing time is 10~20min. The deformation amount of each rolling pass is controlled at 40~45%.

10. The method for preparing titanium-copper alloy plates or strips according to claim 1, characterized in that, In step 5, after the cold rolling is completed, the obtained cold-rolled billet is cleaned on the surface and the oxide slag layer is removed. Then, it is annealed under vacuum or argon protective atmosphere to obtain titanium-copper alloy plates or strips.

Images