Ti-5553 titanium alloy sheet based on low temperature rolling induced plasticity and preparation method

Abstract

The application discloses a kind of Ti-5553 titanium alloy sheet based on low temperature rolling induced plasticity and preparation method, it is related to titanium alloy processing technical field.The preparation method includes: selecting Ti-5553 titanium alloy hot-rolled plate for first low temperature rolling and first solid solution treatment, obtains first rolling range plate;Second low temperature rolling is carried out to first rolling range plate, obtains second rolling range low temperature rolling state plate;Second rolling range low temperature rolling state plate is cut into finished plate;Second solid solution treatment and aging treatment are carried out to finished plate, obtain the Ti-5553 titanium alloy sheet of double-state organization.The application utilizes the stress-induced β→α″ martensitic phase transition induced plasticity of Ti-5553 near β titanium alloy under low temperature condition, inhibits the initiation of rolling crack, realizes the single rolling range superplastic deformation of alloy and short process low temperature rolling, not only meets the performance demand of 1500MPa grade superhigh strength titanium alloy sheet of lightweight composite armor, but also reduces the production cycle and cost of sheet.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy processing technology, and in particular to a Ti-5553 titanium alloy thin plate and its preparation method based on low-temperature rolling-induced plasticity. Background Technology

[0002] Ti-5553 titanium alloy is a commercially available high-strength titanium alloy with a nominal composition of Ti-5Al-5V-5Mo-3Cr (by mass). Due to its ultra-high strength, good impact resistance, and excellent thermal shear properties, it has been used to manufacture high-strength main load-bearing structural components for the landing gear of the A380 large passenger aircraft. The bimodal structure of Ti-5553 titanium alloy exhibits a tensile strength ≥1400MPa, elongation after fracture ≥10%, and initiation strain in the thermal shear band ≥10%, making it an ideal candidate material for lightweight composite armor metal sandwich layers. However, currently, there is no mature and efficient process for preparing ultra-thin sheets of bimodal Ti-5553, and existing cold rolling technologies for titanium alloy sheets have significant limitations.

[0003] Cold rolling is a typical engineering method for the preparation of commercial titanium alloy thin sheets. For example, Chinese patent application CN107755428A discloses a method for preparing high-strength β-titanium alloy thin sheets, proposing a method for preparing β-titanium alloy thin sheets by combining room-temperature cold rolling with segmented annealing to control grain breakage and recrystallization, with a total deformation of 30-60% during the rolling process; Chinese patent application CN112662972A discloses a production process method for ultra-high-strength TA4 titanium alloy strip, proposing a cold rolling method for TA4 titanium alloy strip. The existing cold rolling process for titanium alloy thin plates has a total deformation rate ranging from 12% to 60%. Chinese patent application CN119392142B discloses a method for preparing Ti35 titanium alloy strip, proposing a cold rolling process for Ti35 titanium alloy strip with a total deformation rate ≤60%. Chinese patent CN115430711B discloses a method for preparing high-plasticity TA18 titanium alloy thin plates for capacitor casings, proposing a cold rolling process for TA18 titanium alloy thin plates with a maximum total deformation rate of 72%. It is evident that existing cold rolling methods for titanium alloy thin plates are not suitable for preparing bimodal Ti-5553 titanium alloy thin plates. First, under single-pass high-deformation-rate cold rolling conditions, cracks easily initiate on both sides of the Ti-5553 titanium alloy slab, and these cracks tend to propagate towards the core of the plate, leading to cold rolling cracking. Second, under single-pass low-deformation-rate cold rolling conditions, the number of intermediate annealing cycles is excessive, significantly increasing the preparation cost and reducing the yield.

[0004] Existing technologies also disclose some cryogenic rolling processes for titanium alloys. For example, CN107185963A discloses a cryogenic asynchronous rolling method for Ti6Al4V alloy, which relies on -190℃ cryogenic cooling to refine grains and enrich V element to improve strength; Chinese patent application CN109518107A discloses a general cryogenic rolling and low-temperature tempering process for titanium strips, which improves the strength and toughness of the sheet through -190~-100℃ cryogenic cooling; Chinese patent application CN107779800A discloses the use of liquid nitrogen cryogenic cooling to prepare titanium alloy materials with shape memory properties. The above-mentioned cryogenic rolling technologies are all based on the low-temperature induced twinning plastic deformation mechanism of the close-packed hexagonal α phase in Ti6Al4V titanium alloy and pure titanium. However, the volume fraction of the α phase in the cold-rolled Ti-5553 titanium alloy slab is only 10%, while the volume fraction of the body-centered cubic β phase is as high as 90%. It is evident that existing cryogenic rolling technology cannot solve the industry pain points of Ti-5553 alloy being prone to cracking during room temperature cold rolling and unable to undergo large deformation rolling.

[0005] Therefore, there is an urgent need to develop a rolling process for Ti-5553 titanium alloy thin plates that can suppress rolling cracks, achieve ultra-large plastic deformation in a single rolling pass, and produce thin plates in a short process. Summary of the Invention

[0006] In view of this, the main objective of this invention is to provide a Ti-5553 titanium alloy thin plate and its preparation method based on low-temperature rolling-induced plasticity. By utilizing the stress-induced β→α″ martensitic phase transformation of Ti-5553 near-β titanium alloy under low-temperature conditions to induce plasticity, and suppressing the initiation of rolling cracks through short-process low-temperature rolling technology, the invention achieves single-pass ultra-large plastic deformation of the alloy and short-process low-temperature rolling. This not only meets the performance requirements of lightweight composite armor for 1500MPa-grade ultra-high strength titanium alloy thin plates, but also reduces the production cycle and cost of the thin plates.

[0007] To achieve the above objectives, as a first aspect of the present invention, a method for preparing Ti-5553 titanium alloy thin plates based on low-temperature rolling-induced plasticity is proposed, comprising: selecting a hot-rolled Ti-5553 titanium alloy sheet and performing a first low-temperature rolling and a first solution treatment to obtain a first-pass sheet; performing a second low-temperature rolling on the first-pass sheet to obtain a second-pass low-temperature rolled sheet; cutting the second-pass low-temperature rolled sheet into finished sheets; and performing a second solution treatment and aging treatment on the finished sheets to obtain a Ti-5553 titanium alloy thin plate with a dual-phase microstructure; wherein, the treatment temperatures for the first and second low-temperature rolling are (M... s -20)℃ to (M s +30)℃, M sThe temperature at which the alloy begins its martensitic transformation is 60%-90%; the total deformation rate of the first and second low-temperature rolling passes is 60%-90%, and the deformation rate per pass is <8%; the thickness of the Ti-5553 titanium alloy sheet is 0.1mm~0.6mm.

[0008] Furthermore, the surface roughness of both sides of the Ti-5553 titanium alloy hot-rolled sheet is 0.4-0.8μm.

[0009] Furthermore, the total deformation rate of the second low-temperature rolling process is 62.5%-90%.

[0010] Furthermore, the solution temperature for the first solution treatment is 830℃~840℃, the solution treatment time is 5min~10min, and the cooling method for the solution treatment is argon gas cooling.

[0011] Furthermore, the solution treatment temperature for the second solution treatment is 830℃~840℃, the solution treatment time is 15min~30min, and the cooling method for the solution treatment is furnace cooling with a vacuum degree ≤5×10 -3 Pa, cooling rate ≥120℃ / min.

[0012] Furthermore, the aging treatment temperature is 510℃~530℃, the aging treatment time is 90min, the cooling method is furnace cooling, and the vacuum degree of the aging treatment is ≤5×10⁻⁶. -3 Pa.

[0013] In a second aspect, the present invention provides a Ti-5553 titanium alloy thin plate, which is prepared by the above-described preparation method to obtain a Ti-5553 titanium alloy thin plate with a thickness of 0.1 mm to 0.6 mm.

[0014] Furthermore, the original β grain diameter of the Ti-5553 titanium alloy sheet is ≤20μm, the tensile strength is ≥1500MPa, and the elongation after fracture is ≥8%.

[0015] Based on the above technical solution, it can be seen that the technical solution of the present invention has at least one of the following beneficial effects compared with the prior art: First, the original β diameter of the dual-state Ti-5553 titanium alloy thin plate prepared by this invention is ≤20μm, the tensile strength is higher than 1500MPa, and the elongation after fracture is higher than 8%, which meets the requirements of lightweight composite armor for high-strength titanium alloy thin plates.

[0016] Secondly, this invention utilizes the martensitic phase transformation of the alloy under low-temperature conditions to induce plasticity, that is, to induce α″ martensite in situ during the rolling deformation process to enhance plasticity and tolerate ultra-large deformation. This realizes a short-process low-temperature rolling technology for Ti-5553 titanium alloy thin plates, which can roll Ti-5553 titanium alloy thin plates with a thickness of 0.1mm-0.6mm in only 1-2 rolling passes, shortening the production cycle of Ti-5553 titanium alloy thin plates and reducing the processing cost of thin plates.

[0017] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below.

[0019] Figure 1 This is a flowchart of the preparation method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the cracking of a room-temperature cold-rolled sheet according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of the invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0022] To achieve the above objectives, as a first aspect of the present invention, a method for preparing Ti-5553 titanium alloy thin plates based on low-temperature rolling-induced plasticity is proposed, such as... Figure 1 As shown, it includes: S1: First rolling pass completed: Select Ti-5553 titanium alloy hot-rolled plate for the first low-temperature rolling and the first solution treatment to obtain the first rolling pass plate. This treatment utilizes stress-induced β→α″ martensitic phase transformation to break up the original coarse β grains of hot rolling, providing a uniform matrix for the second large deformation rolling. S2: Complete the second rolling process: Perform a second low-temperature rolling on the first rolling process plate to obtain the second rolling low-temperature rolled plate, and rely on phase transformation-induced plasticity to achieve the ultimate thinning of the plate to the target thickness; S3: Cutting: Cutting the low-temperature rolled sheet in the second rolling process into finished sheet; S4: Heat treatment: The finished plate is subjected to a second solution treatment and aging treatment to obtain a Ti-5553 titanium alloy thin plate with a dual-state structure; the metastable α″ martensite generated by the dissolution rolling in this treatment re-precipitates fine secondary α phase, and finally obtains a dual-state structure of β matrix and fine α phase.

[0023] In the above preparation process, the processing temperatures for the first and second low-temperature rolling are (M) s -20)℃ to (M s +30)℃, M s The temperature at which the alloy begins its martensitic transformation is set, ensuring the β phase reaches a metastable state and possesses the thermodynamic conditions to trigger stress-induced phase transformation. The total deformation rate of the first and second low-temperature rolling passes is 60%-90%, with a per-pass deformation rate of <8%. The thickness of the Ti-5553 titanium alloy sheet is 0.1mm~0.6mm. The total deformation range achieves the large thinning required for ultra-thin 0.1~0.6mm finished products. The deformation per single pass is strictly limited to below 8% to avoid problems such as instantaneous stress overload and edge cracking caused by excessive deformation per pass. The superposition of multiple small deformation passes achieves a large overall total deformation, and each pass continuously activates the phase transformation-induced plastic effect, uniformly dispersing plastic strain and ensuring uniform overall deformation of the sheet.

[0024] In this technical solution, the low-temperature rolling temperature is controlled near the martensitic transformation point. The external rolling force provides stress to drive the β phase to undergo stress-induced martensitic transformation (i.e., transformation-induced plasticity). Metastable α″ martensite is generated during deformation. The martensitic transformation absorbs localized stress concentration, releasing localized stress concentration in the plate during rolling, thus inhibiting crack initiation and propagation at the source. This preparation method differs from the liquid nitrogen cryogenic process below -100℃. This process is only used in M... s Low-temperature rolling is performed nearby, without the need for extreme ultra-low temperatures, and in-situ phase transformation plasticization is achieved solely through rolling stress.

[0025] This technical solution solves the problems of easy cracking due to high deformation rate, frequent annealing for low deformation rate, high cost, and low yield in existing room-temperature cold-rolled Ti-5553. It can achieve ultra-large plastic rolling with a total deformation of up to 90%, eliminating the need for multiple intermediate annealing processes, shortening the process flow, reducing production costs, and improving the yield. sNearby low-temperature rolling significantly improves the rolling plasticity of the alloy, with no through cracks on the edges and core of the plate, and can stably produce ultra-thin Ti-5553 plates with a thickness of 0.1~0.6mm; through precise control of two-stage low-temperature rolling and segmented solid solution and aging, a dual-mode structure plate suitable for lightweight composite armor is finally obtained, which takes into account both ultra-high strength and plasticity, as well as excellent thermal insulation shear resistance.

[0026] In a preferred embodiment, the surface roughness of both sides of the hot-rolled Ti-5553 titanium alloy sheet (i.e., the surface formed by the thickness and length directions of the sheet) is 0.4-0.8 μm. This limited roughness eliminates stress concentration sources from surface defects and, combined with phase transformation-induced plasticity, further prevents cracking. If the surface roughness is too high (>0.8 μm), the uneven surface during rolling will create stress concentration pits that become crack nucleation points, leading to crack propagation from the surface inwards during rolling. Conversely, if the surface roughness is too low (<0.4 μm), it will significantly increase the machining cost of the slab. Appropriate surface roughness significantly reduces the probability of crack initiation on both sides of the slab during low-temperature rolling, thereby improving the forming quality and finished product yield of ultra-thin sheets.

[0027] In a preferred embodiment, the total deformation rate of the second low-temperature rolling pass is 62.5%-90%. The first low-temperature rolling completes the pre-crushing of grains, and the second low-temperature rolling is the core deformation process for thinning the plate to an ultra-thin specification of 0.1~0.6mm. In order to ensure that the overall total deformation can achieve the target ultra-thin thickness for rolling medium-thick plates, the deformation window of the core thinning process is precisely defined, ensuring that the plate can be thinned to an ultra-thin specification of 0.1~0.6mm in one pass with only two low-temperature rolling passes, without the need for additional rolling and intermediate annealing, simplifying the process and stably obtaining the target thickness plate.

[0028] In a preferred embodiment, the solution temperature for the first solution treatment is 830℃~840℃, the solution treatment time is 5min~10min, and the cooling method for the solution treatment is argon gas cooling, using a continuous argon-protected annealing furnace for the first solution treatment. The first solution treatment only dissolves the α″ martensite phase, promoting the recrystallization of β grains; rapid argon cooling can quickly retain the high-temperature supersaturated β solid solution, avoiding the precipitation of coarse α lamellae during cooling, ensuring that the matrix is ​​a uniform fine-grained β phase, providing a highly plastic and uniform matrix for the subsequent secondary large deformation rolling. This treatment can achieve the effects of homogenizing the matrix and refining the original grains, thereby eliminating the residual stress after the first low-temperature rolling, significantly increasing the ultimate deformation that the second low-temperature rolling can withstand, and further suppressing secondary rolling cracks.

[0029] In a preferred embodiment, the solution temperature for the second solution treatment is 830℃~840℃, the solution treatment time is 15min~30min, and the cooling method for the solution treatment is furnace cooling with a vacuum degree ≤5×10⁻⁶.-3 Pa, cooling rate ≥120℃ / min. The second solution treatment fully dissolves the large amount of metastable α″ martensite generated during the second rolling, obtaining a uniformly composed supersaturated β matrix. The vacuum level of the double-chamber vacuum quenching furnace is set to prevent oxidation and oxygen absorption on the Ti alloy surface at 830℃, avoiding surface embrittlement and reduced plate plasticity. Rapid cooling suppresses the precipitation of coarse lamellar α phase during the cooling stage, retaining only a uniform supersaturated β solid solution, laying the microstructure foundation for the subsequent precipitation of ultrafine secondary α phase during aging. The second solution treatment completely eliminates the metastable martensite induced by low-temperature rolling, avoids oxidation defects, and allows for precise control of the supersaturated β matrix after solution treatment, ensuring the formation of a fine and uniform bimodal microstructure after aging, thus stably achieving ultra-high strength of the plate.

[0030] In a preferred embodiment, the aging treatment temperature is 510℃~530℃, the aging treatment time is 90 min, the cooling method for the aging treatment is furnace cooling, and the vacuum degree of the aging treatment is ≤5×10⁻⁶. -3 Pa. 510℃~530℃ is the optimal precipitation temperature for the secondary α phase of Ti-5553. A sufficient aging time of 90min is ensured so that the secondary α lamellae of nanometer thickness are uniformly precipitated in the supersaturated β matrix, forming a dual-state structure. This allows the plate to have both ultra-high tensile strength and excellent elongation, while also improving thermal insulation shear resistance, thus meeting the requirements for composite armor.

[0031] In a second aspect, this invention provides a Ti-5553 titanium alloy thin sheet, prepared using the aforementioned method to obtain a Ti-5553 titanium alloy thin sheet with a thickness of 0.1 mm to 0.6 mm. This technology provides a Ti-5553 ultrathin sheet with a thickness of 0.1 mm to 0.6 mm that is free from rolling cracks, has uniform thickness, and excellent surface quality, filling the gap in the industry for mature ultrathin dual-phase Ti-5553 thin sheet products.

[0032] In a preferred embodiment, the original β diameter of the Ti-5553 titanium alloy sheet is ≤20μm, the tensile strength is ≥1500MPa, and the elongation after fracture is ≥8%. This technology continuously breaks down the original β grains through multi-pass low-temperature rolling with small deformation, combined with two-stage short aging and solution treatment processes, limiting the high-temperature growth of β grains, thereby improving strength and plasticity; by designing a dispersed fine secondary α phase in the dual-state microstructure to generate precipitation strengthening, ultra-high tensile strength is achieved; and by designing a continuous β matrix, a certain degree of plasticity is ensured, avoiding brittle fracture of the material under high strength. It is evident that the ultra-high tensile strength ensures impact and penetration resistance; the adequate elongation avoids brittle fracture during processing or service; and the realization of fine grains significantly improves the initiation strain of the adiabatic shear band, thus meeting the application requirements of lightweight composite armor sandwich cores.

[0033] This invention relies on M sThe low-temperature rolling stress-induced martensitic phase transformation-induced plasticizing mechanism, which differs from existing room-temperature rolling (deformation limited and prone to cracking) and extreme liquid nitrogen cryogenic (based on the α-low-temperature twinning deformation mechanism) technologies, combined with the synergistic control of segmented rolling, segmented solution treatment, surface roughness, and per-pass deformation, achieves ultra-large rolling deformation of 60%~90%, and produces ultra-thin Ti-5553 plates with a thickness of 0.1mm-0.6mm in a single process. Finally, a high-strength and high-toughness plate with a fine-grained dual-state structure is obtained, which solves the industry pain points of existing processes such as cracking, multi-pass annealing, and inability to produce ultra-thin specifications.

[0034]

Example 1

[0035] Step 1, Process the slab: The raw material in this embodiment is a solution-treated Ti-5553 titanium alloy hot-rolled plate. The thickness, width, and length of the solution-treated Ti-5553 titanium alloy hot-rolled plate are 4 mm, 330 mm, and 600 mm, respectively. The composition conforms to ASM7026, and the surface is free of processing defects such as cracks, pits, dents, and scratches.

[0036] Using an HMC630 horizontal machining center, the solution-treated Ti-5553 titanium alloy hot-rolled plate was machined to a size of 4mm×328mm×600mm, resulting in a 4mm×600mm flat surface that forms the side of the slab with a surface roughness Ra=0.8μm.

[0037] Step 2, complete the first rolling pass: The slab is subjected to low-temperature treatment using a low-temperature chamber at a temperature of (M). s +30℃, the low temperature treatment time is 10min, and after the low temperature treatment is completed, a low temperature slab is obtained.

[0038] A 24500kN four-high reversible rolling mill was used to roll a low-temperature slab. The roll dimensions of the mill were Φ450mm × 1200mm. The rolling direction was along the length of the low-temperature slab, and the rolling speed was 30mm / s. Through 13 passes, the thickness of the low-temperature slab was deformed from 4mm to 1.6mm, with a total deformation rate of 60%. The first-pass low-temperature rolled plate was obtained.

[0039] Solution treatment was performed on the first-pass low-temperature rolled sheet using a continuous argon-protected annealing furnace. The solution temperature was 830℃, the solution treatment time was 5 minutes, and the cooling method was argon gas cooling. After solution treatment, a solution-treated sheet was obtained. The solution-treated sheet was then pickled to obtain the first-pass rolled sheet.

[0040] Step 3, complete the second rolling pass: The first-pass rolling sheet was subjected to a second cryogenic treatment using a cryogenic chamber. The temperature of the second cryogenic treatment was (M). s The temperature was -20℃, and the low-temperature treatment time was 10 minutes. After the low-temperature treatment, the first rolling pass plate in the low-temperature state was obtained.

[0041] A 24500kN four-roll reversible rolling mill was used to roll a first-pass low-temperature plate. The mill rolls were Φ450mm×1200mm, and the rolling speed was 30mm / s. The plate was rolled to a thickness of 0.6mm in 14 passes, with a total deformation rate of 62.5%. This yielded a second-pass low-temperature rolled plate.

[0042] Step 4, Cutting: The CNC shearing machine is used to cut the low-temperature rolled sheet in the second rolling process into finished sheets with dimensions of 0.6mm×300mm×600mm.

[0043] Step 5, heat treatment: The finished sheet metal was solution treated using a double-chamber vacuum quenching furnace: the solution temperature was 830℃, the solution treatment time was 15 min, and the vacuum degree of the solution treatment was ≤5×10⁻⁶. -3 Pa, the cooling rate of the solution treatment is ≥120℃ / min. After solution treatment, a solution-treated plate is obtained.

[0044] The solution-treated sheet metal was aged using a vacuum quenching furnace. The aging temperature was 530℃, the aging time was 90 min, and the vacuum degree during aging was ≤5×10⁻⁶. -3 Pa, the aging treatment was cooled by furnace cooling. After aging treatment, a Ti-5553 titanium alloy sheet with a dual-state microstructure and a thickness of 0.6 mm was obtained.

[0045]

Example 2

[0046] Step 1, Process the slab: The raw material in this embodiment is a solution-treated Ti-5553 titanium alloy hot-rolled plate. The thickness, width, and length of the solution-treated Ti-5553 titanium alloy hot-rolled plate are 10 mm, 330 mm, and 600 mm, respectively. The composition conforms to ASM7026, and the surface is free of processing defects such as cracks, pits, dents, and scratches.

[0047] Using an HMC630 horizontal machining center, the solution-treated Ti-5553 titanium alloy hot-rolled plate was machined to a size of 10mm×328mm×600mm, resulting in a 10mm×600mm flat surface as the side of the slab with a surface roughness Ra=0.6μm.

[0048] Step 2, complete the first rolling pass: The slab is subjected to low-temperature treatment using a low-temperature chamber at a temperature of (M). s +10)℃, the low temperature treatment time is 10min, and after the low temperature treatment, a low temperature slab is obtained.

[0049] A 24500kN four-high reversible rolling mill was used to roll a low-temperature slab. The roll dimensions of the mill were Φ450mm × 1200mm. The rolling direction was along the length of the low-temperature slab, and the rolling speed was 30mm / s. Through 23 passes, the thickness of the low-temperature slab was deformed from 10mm to 2mm, with a total deformation rate of 80%. This yielded the first-pass low-temperature rolled slab.

[0050] Solution treatment was performed on the first-pass low-temperature rolled sheet using a continuous argon-protected annealing furnace. The solution temperature was 835℃, the solution treatment time was 7 minutes, and the cooling method was argon gas cooling. After solution treatment, a solution-treated sheet was obtained. The solution-treated sheet was then pickled to obtain the first-pass rolled sheet.

[0051] Step 3, complete the second rolling pass: The first-pass rolling sheet was subjected to a second cryogenic treatment using a cryogenic chamber. The temperature of the second cryogenic treatment was (M). s -10℃, low temperature treatment time is 10min. After the low temperature treatment, the first rolling pass plate in low temperature state is obtained.

[0052] A 24500kN four-roll reversible rolling mill was used to roll a first-pass low-temperature plate. The mill rolls were Φ450mm×1200mm, and the rolling speed was 30mm / s. The plate was rolled to a thickness of 0.5mm in 20 passes, with a total deformation rate of 75%. This yielded a second-pass low-temperature rolled plate.

[0053] Step 4, Cutting: The CNC shearing machine is used to cut the low-temperature rolled sheet in the second rolling process into finished sheets with dimensions of 0.5mm×300mm×600mm.

[0054] Step 5, heat treatment: The finished sheet metal was solution treated using a double-chamber vacuum quenching furnace: the solution temperature was 835℃, the solution treatment time was 25 min, and the vacuum degree of the solution treatment was ≤5×10⁻⁶. -3 Pa, the cooling rate of the solution treatment is ≥120℃ / min. After solution treatment, a solution-treated plate is obtained.

[0055] The solution-treated sheet metal was aged using a vacuum quenching furnace. The aging temperature was 510℃, the aging time was 90 min, and the vacuum degree during aging was ≤5×10⁻⁶. -3 Pa, the aging treatment was cooled by furnace cooling. After aging treatment, a Ti-5553 titanium alloy sheet with a dual-state microstructure and a thickness of 0.5 mm was obtained.

[0056]

Example 3

[0057] Step 1, Process the slab: The raw material in this embodiment is a solution-treated Ti-5553 titanium alloy hot-rolled plate. The thickness, width, and length of the solution-treated Ti-5553 titanium alloy hot-rolled plate are 10 mm, 330 mm, and 600 mm, respectively. The composition conforms to ASM7026, and the surface is free of processing defects such as cracks, pits, dents, and scratches.

[0058] Using an HMC630 horizontal machining center, the solution-treated Ti-5553 titanium alloy hot-rolled plate was machined to a size of 10mm×328mm×600mm, resulting in a 10mm×600mm flat surface as the side of the slab with a surface roughness Ra=0.4μm.

[0059] Step 2, complete the first rolling pass: The slab is subjected to low-temperature treatment using a low-temperature chamber at a temperature of (M). s +5)℃, the low temperature treatment time is 40min, and after the low temperature treatment is completed, a low temperature slab is obtained.

[0060] A 24500kN four-high reversible rolling mill was used to roll a low-temperature slab. The roll dimensions of the mill were Φ450mm × 1200mm. The rolling direction was along the length of the low-temperature slab, and the rolling speed was 30mm / s. Through 33 passes, the thickness of the low-temperature slab was deformed from 10mm to 1mm, with a total deformation rate of 90%. This yielded the first-pass low-temperature rolled slab.

[0061] Solution treatment was performed on the first-pass low-temperature rolled sheet using a continuous argon-protected annealing furnace. The solution temperature was 840℃, the solution treatment time was 10 min, and the cooling method was argon gas cooling. After solution treatment, a solution-treated sheet was obtained. The solution-treated sheet was then pickled to obtain the first-pass rolled sheet.

[0062] Step 3, complete the second rolling pass: The first-pass rolling sheet was subjected to a second cryogenic treatment using a cryogenic chamber at a temperature of M. sThe temperature was set at ℃, and the low-temperature treatment time was 10 minutes. After the low-temperature treatment, the first rolling pass plate in a low-temperature state was obtained.

[0063] A 2940kN four-roll reversible rolling mill was used to roll a first-pass low-temperature plate. The mill rolls had dimensions of Φ450mm × 550mm, and the rolling speed was 30mm / s. The plate was rolled to a thickness of 0.1mm in 33 passes, with a total deformation rate of 90%. This yielded a second-pass low-temperature rolled plate.

[0064] Step 4, Cutting: The CNC shearing machine is used to cut the low-temperature rolled plate in the second rolling process into finished plates with dimensions of 0.1mm×300mm×600mm.

[0065] Step 5, heat treatment: The finished sheet metal was solution treated using a double-chamber vacuum quenching furnace: the solution temperature was 840℃, the solution treatment time was 30 min, and the vacuum degree of the solution treatment was ≤5×10⁻⁶. -3 Pa, the cooling rate of the solution treatment is ≥120℃ / min. After solution treatment, a solution-treated plate is obtained.

[0066] The solution-treated sheet metal was aged using a vacuum quenching furnace. The aging temperature was 520℃, the aging time was 90 min, and the vacuum degree during aging was ≤5×10⁻⁶. -3 Pa, the aging treatment was cooled by furnace cooling. After aging treatment, a Ti-5553 titanium alloy sheet with a dual-state microstructure and a thickness of 0.1 mm was obtained.

[0067] Comparative Examples 1-3 Based on Example 2, the low-temperature treatment temperature and heat treatment temperature were changed to prepare thin plates. The specific process parameters are shown in the table below.

[0068] The different process parameters in Examples 1-3 and Comparative Examples 1-3 are summarized in the table below: Table 1. Different process parameters and performance data in each embodiment and comparative example. As can be seen from the preparation and data of the embodiments, the low-temperature rolling method of this application can effectively prepare thickness and performance that meet the requirements of thin plates; The preparation and data of Comparative Examples 1-2, which also use low-temperature rolling, show that when the low-temperature treatment temperature is changed, the slab will crack and fail to meet the thickness requirements when the total rolling deformation rate does not meet the requirements.

[0069] First, when the low-temperature treatment temperature is higher than the low-temperature treatment temperature range proposed in this invention, such as in Comparative Example 2, the Ti-5553 titanium alloy will not undergo stress-induced martensitic transformation during the rolling deformation process, and the total deformation rate of the rolling process will be greatly reduced, making the plastic deformation capacity of the material lower than that of the material within the low-temperature treatment temperature range proposed in this invention.

[0070] Secondly, when the low-temperature treatment temperature is lower than the low-temperature treatment temperature range proposed in this invention, such as in Comparative Example 1, the transformation amount of stress-induced martensite in the alloy during rolling deformation is lower than the transformation amount within the low-temperature treatment temperature range proposed in this invention. At this time, the plastic deformation capacity of the material is still lower than the plastic deformation capacity of the material within the low-temperature treatment temperature range proposed in this invention.

[0071] The parameters and performance of Comparative Example 3, which also uses low-temperature rolling, show that changing the solution treatment and aging treatment temperatures alters the volume fraction of the primary α phase and the thickness of the secondary α phase, resulting in the final thin plate failing to meet performance requirements.

[0072] Comparative Example 4 The raw material for this comparative example is a solution-treated Ti-5553 titanium alloy hot-rolled plate. The thickness, width, and length of the solution-treated Ti-5553 titanium alloy hot-rolled plate are 10 mm, 102 mm, and 210 mm, respectively. The composition conforms to ASM7026, and the surface is free of processing defects such as cracks, pits, dents, and scratches.

[0073] The solution-treated Ti-5553 titanium alloy hot-rolled plate was machined to a size of 10mm × 100mm × 210mm using an HMC630 horizontal machining center to obtain a slab. The 10mm × 210mm plane is the side surface of the slab, and its surface roughness Ra = 0.4μm.

[0074] Slabs were rolled at room temperature using a 24500kN four-high reversible rolling mill. The mill rolls had dimensions of Φ450mm × 1200mm. The rolling direction was along the length of the slab, and the rolling speed was 30mm / s. Cracks appeared in the slab when the rolling deformation rate was only 41%. Figure 2 For cracked plates, it is impossible to achieve short-process preparation of thin plates.

[0075] The foregoing has described specific embodiments of the present invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing Ti-5553 titanium alloy thin plates based on low-temperature rolling-induced plasticity, characterized in that, include: Ti-5553 titanium alloy hot-rolled plate was selected and subjected to a first low-temperature rolling and a first solution treatment to obtain the first rolling pass plate. The first-pass plate is subjected to a second low-temperature rolling process to obtain a second-pass low-temperature rolled plate. The sheet material in the low-temperature rolled state of the second rolling process is cut into finished sheet material; The finished sheet material undergoes a second solution treatment and aging treatment to obtain a Ti-5553 titanium alloy thin sheet with a dual-phase microstructure; among which... The processing temperatures for the first and second low-temperature rolling processes are (M) s -20)℃ to (M s +30)℃, M s This is the temperature at which the martensitic transformation of the alloy begins. The total deformation rate of the first and second low-temperature rolling passes is 60%-90%, and the deformation rate per pass is <8%. The thickness of Ti-5553 titanium alloy thin plates ranges from 0.1mm to 0.6mm.

2. The preparation method according to claim 1, characterized in that, The surface roughness of both sides of the hot-rolled Ti-5553 titanium alloy sheet is 0.4-0.8μm.

3. The preparation method according to claim 1, characterized in that, The total deformation rate of the second low-temperature rolling process is 62.5%-90%.

4. The preparation method according to claim 1, characterized in that, The solution temperature for the first solution treatment was 830℃~840℃, the solution treatment time was 5min~10min, and the cooling method for the solution treatment was argon gas cooling.

5. The preparation method according to claim 1, characterized in that, The second solution treatment was carried out at a temperature of 830℃~840℃ for 15min~30min, using furnace cooling with a vacuum degree ≤5×10⁻⁶. -3 Pa, cooling rate ≥120℃ / min.

6. The preparation method according to claim 1, characterized in that, The aging treatment temperature is 510℃~530℃, the aging treatment time is 90min, the cooling method is furnace cooling, and the vacuum degree of the aging treatment is ≤5×10. -3 Pa.

7. A Ti-5553 titanium alloy thin plate, characterized in that, Ti-5553 titanium alloy thin plates with a thickness of 0.1 mm to 0.6 mm were prepared by the preparation method described in any one of claims 2-9.

8. The Ti-5553 titanium alloy sheet according to claim 7, characterized in that, The original β grain diameter of Ti-5553 titanium alloy sheet is ≤20μm, the tensile strength is ≥1500MPa, and the elongation after fracture is ≥8%.

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