CN115971249A - Preparation method of ultrathin TC4 titanium alloy plate - Google Patents
Preparation method of ultrathin TC4 titanium alloy plate Download PDFInfo
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Abstract
The invention relates to a preparation method of an ultrathin TC4 titanium alloy plate, which comprises the steps of hot rolling cogging, hot rolling two times, quenching, hot rolling three times, double-sheet pack rolling, steel plate cladding rolling, cold rolling and step annealing. The total deformation rate of the titanium alloy plate reaches more than 99 percent, and the blank with various thicknesses can be formed into an ultrathin plate with the thickness as low as 0.4 mm. By the combined hot rolling process of multi-heat hot rolling, double-sheet stack rolling, steel plate cladding rolling and the like, the plate is rolled in small variable and multiple passes, the anisotropy of the plate is obviously weakened, the effects of uniform crystal grains, improved microstructure and improved macroscopic mechanical property are obtained, the risks of plate cracks, deformation, edge breakage and the like are reduced, and the production pressure of subsequent cold rolling is effectively relieved. The surface quality of the plate is improved by utilizing links such as surface treatment, cold rolling process, online step annealing and the like, the tolerance and the same plate difference of the plate are effectively controlled, and the ultrathin TC4 titanium alloy plate with stable quality and excellent comprehensive performance can be obtained without subsequent processes such as vacuum creep correction and the like.
Description
Technical Field
The invention belongs to the technical field of titanium alloy plate processing, and particularly relates to a preparation method of an ultrathin TC4 titanium alloy plate.
Background
With the development of the industries such as the automobile industry, the aviation industry, the electronic communication industry and the like, people increasingly have an enhanced requirement on high-performance titanium alloy plates. As a new material, titanium alloys have advantages such as high specific strength, good heat resistance and corrosion resistance, and play an important role in structural metal materials. The TC4 titanium alloy material is Ti-6Al-4V, belongs to (alpha + beta) type titanium alloy, has good comprehensive mechanical properties, and is the most widely applied titanium alloy. However, the TC4 titanium alloy can form a strong deformation texture in the rolling process due to the reasons of small heat conductivity, poor heat conductivity and the like, the existence of the texture shows strong anisotropy, so that the rolled piece has the problems of plasticity reduction, uneven deformation, edge cracking, surface cracks and the like, and the development and application of the TC4 titanium alloy are greatly limited. In the aspect of application forms, a titanium alloy plate is the most widely used form of a titanium alloy product, and the production process of the plate is the key and difficult point in the technical field of titanium alloy processing, wherein the production of the ultrathin TC4 titanium alloy plate is the most difficult part in the plate production and is limited by roller conditions and the like, thin plates with the thickness of less than 0.6mm are easy to have different thicknesses, the control difficulty of the difference between the same plates is high, and the roller can be damaged due to the overpressure of a rolling mill.
The method for simultaneously rolling a plurality of superposed titanium alloy plates by adopting steel plate cladding rolling is an effective method for reducing the thickness of a single plate at present. Patent CN113333469B discloses a TC4 titanium alloy sheet hot rolling process, which comprises the procedures of substrate preparation, rolling package preparation, first rolling, secondary rolling, annealing and post-treatment, wherein the TC4 titanium alloy sheet is produced by adopting a small-deformation multi-fire rolling process, the anisotropy of the sheet is obviously reduced, meanwhile, when the rolling package is prepared, one end of the substrate is welded and fixed, the substrate is prevented from slipping and dislocating in the rolling process, and the prepared TC4 titanium alloy sheet has low same-sheet difference; set up the inflation inlet at rolling the edge of encapsulating, follow the inflation inlet and let in argon gas when rolling first, let in argon gas to the heating furnace during to the preheating of rethreshing for the base plate is protected by argon gas all the time under high thermal state, alleviates titanium alloy oxidation, eliminates many times of fires and rolls and cause the too thick influence panel thickness of oxide layer and draw crack production problem. However, because the total deformation is low, the method is suitable for processing the titanium alloy plate with a thin initial thickness, and the titanium alloy plate blank with a large thickness before cladding and rolling is difficult to process and regulate; and the temperature of the alloy is reduced by 8-10 ℃/min, and the alloy is isothermally annealed to room temperature along with a heating furnace, so that the treatment efficiency is low.
Patent CN113564500B provides a preparation method of a high-strength ultra-fine grain TC4 titanium plywood, which includes: (1) Heating a TC4 titanium alloy ingot at 1000-1100 ℃, cogging and forging to obtain a blank; (2) Heating at 850-920 ℃, and rolling the blank; (3) Performing heat treatment at the temperature of 30-50 ℃ above the beta transformation point, and then performing water quenching and cooling to obtain a plate blank; (4) heating at 850-920 ℃ and then rolling; (5) Assembling and welding the obtained blank to obtain a steel plate coated rolling package; (6) Heating at 800-850 ℃, and rolling for the fourth time; (7) Disassembling the rolling package, and performing second assembly welding on the blank to obtain a steel plate coated rolling package; (8) Heating at 800-850 ℃, and rolling in a direction perpendicular to the last rolling direction; (9) Annealing, creep deformation correction, alkali acid washing and sanding are carried out, and then a plate with the thickness of 0.4mm is obtained; and then preparing the titanium alloy foil. The invention adopts two times of steel plate cladding rolling, and the cost is higher; and the TC4 thin plate with stable performance can be obtained only by creep deformation correction and other treatments after annealing, and is not suitable for large-scale flow line production.
Therefore, the thickness to be rolled is increased by increasing the number of the plates, and the preparation of a single ultrathin plate is completed by cladding rolling by using the conventional equipment, so that the method is an effective means for obtaining the ultrathin titanium alloy plate. And a plate blank with moderate and uniform thickness is obtained before cladding and rolling, and the ultrathin veneer is effectively subjected to aftertreatment after unpacking, which is an important condition for obtaining the ultrathin TC4 titanium alloy finished plate with high quality and high efficiency. How to design a process link and adjust and control forming parameter conditions to obtain a TC4 titanium alloy sheet with thin thickness, uniform microstructure and excellent comprehensive performance becomes a technical problem to be solved urgently in the field.
Disclosure of Invention
In view of the above-mentioned defects in the prior art, the present invention aims to provide a method for preparing an ultra-thin TC4 titanium alloy plate. By comprehensively designing all links of the process flow, integrally adopting five-step large-deformation hot rolling and combining multi-pass reversing hot rolling in all the steps, the aims of refining grains and homogenizing tissues are achieved, the ultrathin TC4 titanium alloy plate which is full in micro-grain crushing, good in tissue uniformity, thin in macroscopic thickness and excellent in comprehensive performance is effectively obtained, the preparation time is effectively shortened, and the production cost is reduced.
Specifically, the invention provides a preparation method of an ultrathin TC4 titanium alloy plate, which comprises the following steps:
the method comprises the following steps: hot rolling and cogging, heating the titanium alloy blank at 920-1000 ℃ for 120-180min, and hot rolling to the thickness of 25-35mm; cutting into rough rolling blanks;
step two: hot rolling with two heats, heating the rough rolling blank at 900-950 ℃ for 30-50min, reversing hot rolling to obtain a two-heat plate blank with the thickness of 8-12 mm;
step three: heating the second fire plate blank at 1040 +/-20 ℃ for 20-30 minutes, and water quenching;
step four: hot rolling with three fires, heating the plate blank obtained in the step three at 900-950 ℃ for 20-30min, reversing hot rolling to obtain a three-fire plate blank with the thickness of 4-5mm;
step five: double-sheet pack rolling, namely stacking the three hot plate blanks in a mode of two sheets in a group and welding the stacked plate blanks into a pack roll pack, and rolling to obtain a pack rolled plate blank with the thickness of a single sheet of 2-2.5 mm;
step six: cladding and rolling a steel plate, and stacking and welding a plurality of the stacked rolled blanks; coating and welding the upper layer steel plate and the lower layer steel plate to obtain a coated rolling package; heating the clad rolling packet at 820-880 ℃ for 30-40min, and reversing hot rolling to obtain a clad rolling plate blank with the thickness of a single plate of 0.4-0.5 mm;
step seven: cold rolling, namely performing 1-pass cold rolling on the clad-rolled plate blank to obtain a cold-rolled plate blank with the deformation rate of less than 10%;
step eight: and (5) step annealing treatment.
According to the invention, a plurality of hot rolling links are designed before cold rolling, particularly repeated reversing hot rolling, double-sheet overlapping rolling and steel plate cladding rolling, the titanium alloy blank can be effectively and stably rolled to a lower thickness by utilizing the existing rolling equipment in a hot rolling multi-fire large-deformation rolling mode, and the cold rolling pressure is remarkably relieved. Because the thickness of two or more plate blanks is reduced in almost the same proportion in the double-plate pack rolling and the steel plate cladding rolling, the single plate blank with high quality and high size uniformity is obtained before the double-plate pack rolling and the steel plate cladding rolling steps, the important condition for effectively controlling the double-plate pack rolling and the steel plate cladding rolling results is that the thickness of the three-fire plate blank is controlled to be 4-5mm, preferably 4-4.5mm, and the double-plate pack rolling step is more favorably carried out. The maximum effect of the double-sheet stack rolling and the steel plate cladding rolling of the invention is to overcome the rolling limit of the minimum thickness of the hot rolling mill, and greatly improve the production efficiency while optimizing the structure.
In addition, in consideration of hot rolling cogging equipment and conditions, the initial thickness of the titanium alloy billet in the step one is preferably 100 to 130mm. After cutting into a rough rolled blank of a smaller size, the rough rolled blank is preferably subjected to grinding wheel to remove scale on the surface and surface defects developed by rolling. As the TC4 titanium alloy is used as the two-phase titanium alloy with lower concentration of alloy elements, in the third step, the two-fire plate blank is heated to the temperature above the phase transition temperature for heat preservation, and then water quenching is carried out to obtain the metastable phase of martensite, which is beneficial to being converted into the dispersed (alpha + beta) phase in the subsequent processing process and obtain the maximum aging strengthening effect.
Further, at least one of the three hot plate blanks, the pack rolled plate blanks and the pack rolled plate blanks is subjected to alkaline pickling treatment, wherein the alkaline pickling treatment comprises the following steps:
A. alkali washing: soaking the plate blank in alkali melt liquid at 460-520 ℃ and carrying out alkali washing for 5-20 min; said alkali melt is composed of 85-95wt% NaOH and 5-15wt% NaNO 3 Forming;
B. primary acid washing: soaking the thin slab in a first acid solution at the temperature of below 60 ℃, pickling for less than 2min, and washing with water and drying; the first acid solution comprises: 5 to 15wt% of 2 SO 4 And the balance being water;
C. secondary acid washing: soaking the thin slab in a second acid solution at the temperature of below 60 ℃, and pickling for less than 10min; the second acid solution contains: 30 to 40wt% of HNO 3 4 to 5% wtHF and the balance water.
Further, the plate blank after the alkali and acid washing treatment is subjected to grinding wheel polishing treatment, and a diamond grinding wheel is adopted, so that the method comprises the following steps:
s1, coarse grinding: the granularity of the rough grinding wheel is 100-120 meshes, the rotating speed is 1200-1800r/min, the feeding amount is 0.02 mm-0.05 mm each time, and the feeding speed of the diamond grinding wheel is 800 mm/min-1000 mm/min;
s2, semi-fine grinding: the granularity of the semi-fine grinding wheel is 120-200 meshes, the rotating speed is 1500 r/min-2000 r/min, the feeding amount is 0.01 mm-0.02 mm each time, and the feeding speed is 500 mm/min-700 mm/min;
s3, fine grinding: the grain size of the fine grinding wheel is 200-300 meshes, the rotating speed is 3500 r/min-4000 r/min, the feeding amount is less than 0.01mm each time, and the feeding speed is 300 mm/min-450 mm/min.
The alkali pickling treatment and the grinding wheel polishing treatment are respectively carried out on the three-fire plate blanks and the pack-rolled plate blanks, so that the double-piece pack-rolling and steel plate cladding rolling quality is improved; the processing is carried out on the wrapped and rolled plate blank, which is beneficial to the surface quality of the final product. In the alkaline pickling treatment, the treatment time can be adjusted accordingly as the slab thickness decreases. After the step annealing treatment in the eighth step, alkali pickling may be performed according to the surface quality of the finished plate, but since the plate thickness is low and the sizing process is almost completed, the treatment time can be reduced, for example, the alkali pickling time can be shortened to 1 to 10min. The plate blank is processed by adopting a grinding wheel grinding mode of coarse grinding, semi-fine grinding and fine grinding, mainly aiming at the characteristic of relatively low plasticity of the TC4 titanium alloy plate, the required grinding requirement is gradually met by adopting a step-by-step grinding mode, and the plate blank is prevented from being damaged.
Further, in the second step, 2 times of vertical reversing hot rolling are carried out, the deformation rate is 60-75%, and the method comprises the following steps:
s2.1: single rolling along the width direction of the plate blank;
s2.2: the slab is rotated by 90 degrees and rolled along the length direction of the slab.
Further, in the fourth step, 2-pass reversing hot rolling is carried out, and the method comprises the following steps:
s4.1: adopting a different-speed asynchronous rolling mill to roll along the width direction of the plate blank once and an upper rollerVelocity V 1 : lower roll speed V 2 1.2-1.5;
s4.2: rotating the plate blank by 90 degrees, adopting a reducing asynchronous rolling mill to roll the plate blank in one time along the length direction of the plate blank, and obtaining the diameter R of an upper roller 1 : diameter of lower roll R 2 Is 1: (1.1-1.3).
Asynchronous rolling generally comprises different-speed asynchronous rolling and different-diameter asynchronous rolling, and mainly utilizes the different linear velocities of an upper roller and a lower roller to enable a rolled piece to bear additional shear deformation. The invention adopts an asynchronous rolling mode in three hot rolling passes, fully utilizes the characteristics of severe plastic deformation, high precision and the like of the asynchronous rolling, and is beneficial to improving the rolling efficiency and quality of the titanium alloy plate. After the hot rolling and the three heating, the martensite obtained in the third step is further decomposed into alpha and beta phases, the alloy is strengthened in the dispersion process, meanwhile, the mechanical properties such as plasticity and the like and the dimensional precision of the titanium alloy plate are improved due to grain refinement, the subsequent rolling passes can be relatively reduced, and the productivity is improved.
Further, in the fifth step, the pack-rolled steel is heated at 900 +/-20 ℃ for 30-40min, and 2-pass reversing hot rolling is carried out, wherein the method comprises the following steps:
s5.1: rolling the pack in a single time along the width direction of the pack, and reducing the thickness of the pack to 6-7mm;
s5.2: rotating the plate blank by 90 degrees, and rolling the plate blank once along the length direction of the pack, wherein the thickness of the pack is reduced to 4-5mm;
s5.3: and splitting the pack to obtain a pack rolled plate blank with the thickness of a single sheet of 2-2.5 mm.
And in the double-sheet pack rolling, the minimum specification of the hot pack rolling is reduced by utilizing the thickness superposition sum phase change of two sheet blanks, and the minimum thickness specification limit of a rolling mill is broken through (for example, the minimum rolling thickness of a part of hot rolling mills is about 3.5 mm). Compared with steel plate cladding rolling, the double-sheet rolling has the advantages that although the deformation degree of a single sheet is generally not the same as that of steel plate cladding rolling, the double-sheet rolling does not need to clad a steel plate, the cost is lower, the efficiency is high, and the production rhythm is fast; in addition, the thickness of the plate can be clearly monitored in the rolling process, and the rolling effect is more visual and controllable than the situation that the rolling effect can be determined only after the plate is wrapped and rolled and even unpacked. The precise double-piece lap rolling is performed for one round before the steel plate is coated and rolled, so that a plate blank with uniform thickness and size can be better provided, and the coating and rolling quality of the subsequent steel plate is obviously improved. Before the two sheets are rolled, two cut and stacked three-hot plate blanks are welded by argon arc welding or laser welding and other modes.
Further, in the steel plate cladding rolling of the step six, before rolling, 4 to 8 pieces of the laminated rolling blanks are stacked and the edges are fully welded, the roughness of the inner sides of the upper layer steel plate and the lower layer steel plate is less than or equal to 1.5 mu m, and the thickness T of the upper layer steel plate and the lower layer steel plate is equal to g0 Total thickness T of rolled and rolled blank t0 Respectively satisfy: t is a unit of g0 ≥T t0 。
Further, the steel plate is subjected to cladding rolling by adopting 2-pass reversing hot rolling, and is subjected to single rolling along the width direction of the plate blank, wherein the deformation rate is alpha; rotating the plate blank by 90 degrees, and rolling the plate blank in a single time along the length direction of the plate blank, wherein the deformation rate beta and the total deformation rate alpha + beta of the steel plate cladding rolling are 75-85%;
the single rolling in the slab width direction satisfies formula (1):
H z1 ＝(1-α)T t0 +T g0 ×2×(1-λ×α) (1)
the single rolling along the length direction of the plate blank satisfies the formula (2):
wherein, before rolling, the total thickness T of the stacked titanium alloy rolled blanks t0 Thickness T of upper or lower steel plate g0 Steel-to-titanium elongation ratio λ; clad-rolled package thickness H after single rolling along slab width direction z1 (ii) a Clad-rolled package thickness H after single rolling along slab length direction z2 By sequential detection of H z1 And H z2 And obtaining the clad rolling plate blank with the veneer thickness of 0.4-0.5 mm.
Because the titanium alloy plate is wrapped in the steel plate, the actual thickness of the rolled titanium alloy plate is difficult to measure in time, and according to the law of volume invariance, a mode of estimating the extension ratio of the steel plate and the titanium alloy plate by utilizing the length change of the steel plate and the titanium alloy plate along the rolling direction and further estimating the rolling thickness of the titanium alloy plate is designed. Specifically, the lambda value is approximately between 1.04 and 1.08. According to the calculation, the thickness reduction degree of the titanium alloy plate can be estimated according to the set deformation rate after single rolling, the size of the steel clad-rolled batch production clad-rolled plate blank is ensured, and the rolling condition is rapidly adjusted according to the measurement result. Optionally, the ratio of the deformation rate alpha to the deformation rate beta is (35-40): (40-45).
Through the steel plate cladding rolling process, alpha-phase and beta-phase two-phase structures in the titanium alloy plate are more fully crushed, and fine and uniform equiaxial crystals with transverse and longitudinal structures are obtained. The upper steel sheet and the lower steel sheet are preferably used in the same thickness according to the number and thickness of the stacked titanium alloy sheets. In practice, the thickness of the upper steel plate or the lower steel plate is generally 15-20mm. It is not excluded to choose different thicknesses for the upper and lower steel plates as the case may be.
Through the steel plate cladding rolling, the optimized alkali pickling and grinding wheel polishing treatment and the optional stress relief annealing treatment, the plate blank with lower plate thickness and better surface performance can be obtained, the subsequent cold rolling pressure is effectively reduced, and the control on the same plate difference of the plate blank thickness is facilitated. The cold rolling of the invention only needs 1 pass of rolling, and the deformation rate is below 10%, the main purpose is not to reduce the plate thickness, but to further reduce the roughness of the plate blank surface after the prior rolling, avoid 25-30% of intangible loss caused by the matching of the prior steel plate cladding rolling and sanding process, and greatly improve the production efficiency and the qualification rate of finished products.
Further, in the eighth step, 4-6 cold-rolled plate blanks are coated between the upper template and the lower template which are 4-6mm in thickness respectively; carrying out on-line heating by using a 50-100kW all-solid-state high-frequency induction heating device, wherein the heating rate is 300-500 ℃/min, the heating is carried out to 800-880 ℃, and the heat preservation time t and the total thickness h of the cold-rolled plate blank meet the following requirements: h x 10min is less than or equal to t is less than or equal to h x 15min.
Preferably, after heat preservation, step cooling treatment is performed, and the method comprises the following steps:
s8.1: cooling the plate blank to 600 ℃ at the speed of not higher than 40 ℃/min;
s8.2: cooling the plate blank to 300 ℃ at a speed of not higher than 60 ℃/min;
s8.3: the slab is cooled to room temperature at a rate of not more than 100 deg.C/min.
The high-frequency induction heating device is adopted, the heating rate, the heat preservation time and the like of the plate to be treated are set according to the conditions of the property, the size and the like of the plate to be treated, the uniform heating can be realized quickly and accurately, the heating efficiency is high, and the loss is less. The upper and lower templates are coated and annealed, and the deformation generated in the transmission process of the online roller way is solved through the thickness support of the templates and the flatness of the templates.
After the cold rolling process, the invention adopts the step annealing treatment, namely the modes of rapid heating and step cooling to rapidly anneal 4-6 cold-rolled plates, the plates have a relatively stable temperature gradient by means of temperature control and are uniformly cooled, the plate deformation caused by nonuniform thermal stress in the plates in the common air cooling process is solved, the plate shape and the performance are completed at one time, the subsequent shape correction treatment is not needed, and compared with the shape correction period of more than 15 days for stacking and straightening a plurality of plate blanks commonly used in the field, the invention has the advantages of high efficiency, reliable quality, smooth and flat finished plates and uniform size.
The invention has the advantages that:
1) According to the characteristics of the TC4 titanium alloy, a hot rolling process flow is reasonably set, particularly large-deformation multi-pass hot rolling is combined with double-sheet stack rolling and steel plate cladding rolling, the thickness of a plate blank is effectively reduced, and an ultrathin TC4 titanium alloy plate is obtained macroscopically; and the microstructure of the titanium alloy micro crystal grain is regulated and homogenized, the problem of the anisotropy of the plate is reduced, and the ultrathin TC4 titanium alloy plate with uniform and stable size, excellent comprehensive properties such as mechanical strength and plasticity and the like is obtained.
2) The double-sheet rolling and steel plate cladding rolling used in the invention effectively overcomes the rolling limit of the minimum thickness of the hot rolling mill, and greatly improves the production efficiency while optimizing the structure. Particularly, the double-sheet pack rolling is arranged before the steel plate is clad and rolled, so that a high-precision plate blank can be efficiently and inexpensively provided for the steel plate cladding and rolling, the characteristics of the steel plate cladding and rolling can be fully exerted, and the clad and rolled plate blank with thin thickness and good uniformity can be effectively obtained; the subsequent cold rolling pressure is reduced on the whole, and the effect of cold rolling high surface quality can be effectively exerted.
3) The special step annealing treatment is realized by selecting a proper plate blank number and a template coating mode, and adopting an online step annealing mode of rapid heating and step cooling, so that the plate blank heating and cooling can be efficiently and uniformly carried out, the internal stress of the plate is fully released, the regulation and control of the plate shape and the performance are completed at one time, the subsequent shape correcting treatment is not needed, and the efficiency of the special step annealing treatment is far higher than that of single plate annealing or stacking and pressing treatment of a plurality of plate blanks.
Drawings
The above and other objects, features and advantages of exemplary embodiments of the present disclosure will become readily apparent from the following detailed description read in conjunction with the accompanying drawings. Several embodiments of the present disclosure are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which:
FIG. 1 is a process flow diagram of the production process of the present invention;
FIG. 2 is a TEM bright field image and a dark field image of a sample of example 1 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below.
The invention provides a preparation method of an ultrathin TC4 titanium alloy plate, which comprises the following steps:
the method comprises the following steps: hot rolling and cogging, heating the titanium alloy blank at 920-1000 ℃ for 120-180min, and hot rolling to the thickness of 25-35mm; cutting into rough rolling blanks; preferably, the initial thickness of the titanium alloy blank is 100-130mm;
optionally, grinding the rough rolling blank by using a grinding wheel to remove oxide skin on the surface and surface defects appearing due to rolling;
step two: hot rolling with two heats, heating the rough rolling blank at 900-950 ℃ for 30-50min, and performing 2-pass vertical reversing hot rolling to obtain a two-heat plate blank with the thickness of 8-12mm, wherein the total deformation rate of the hot rolling with two heats is 60-75%, and the method comprises the following steps:
s2.1: rolling along the width direction of the plate blank, wherein the single deformation rate is 25-30%;
s2.2: the plate blank is rotated by 90 degrees and rolled along the length direction of the plate blank, and the single deformation rate is 35-50 percent.
Step three: heating the second fire plate blank at 1040 +/-20 ℃ for 20-30 minutes, and water quenching at 30-40 ℃;
step four: hot rolling with three heats, heating the plate blank obtained in the step three at 900-950 ℃ for 20-30min, reversing hot rolling to obtain a three-heat plate blank with the thickness of 4-5mm; the reversing hot rolling is preferably carried out by 2-pass reversing hot rolling, and comprises the following steps:
s4.1: adopting a different-speed asynchronous rolling mill to roll the plate blank in one time along the width direction of the plate blank, and the speed V of the upper roller 1 : lower roll speed V 2 1.2-1.5;
s4.2: rotating the plate blank by 90 degrees, adopting a reducing asynchronous rolling mill to roll the plate blank in a single time along the length direction of the plate blank, and measuring the diameter R of an upper roll 1 : diameter of lower roller R 2 Is 1: (1.1-1.3);
optionally, carrying out alkali pickling treatment and grinding wheel polishing treatment on the three-fire plate blank;
step five: double-sheet rolling, namely cutting the three hot plate blanks into the same size, stacking two hot plate blanks in a group, welding the stacked two hot plate blanks into a rolling package, and rolling to obtain a single rolled plate blank with the thickness of 2-2.5 mm; preferably, the pack rolling package is heated at 900 +/-20 ℃ for 30-40min, and 2-pass reversing hot rolling is carried out, and the method comprises the following steps:
s5.1: rolling the pack in a single time along the width direction of the pack, and reducing the thickness of the pack to 6-7mm;
s5.2: rotating the plate blank by 90 degrees, and rolling the plate blank once along the length direction of the pack, wherein the thickness of the pack is reduced to 4-5mm;
s5.3: splitting the pack to obtain a pack-rolled plate blank with the thickness of a single sheet of 2-2.5 mm;
optionally, performing alkali pickling treatment and grinding wheel polishing treatment on the rolled plate blank; cutting the plate blank into the same length and width dimensions;
step six: cladding and rolling a steel plate, stacking and welding a plurality of the laminated rolled blanks, preferably stacking 4-8 laminated rolled blanks and fully welding the edges of the laminated rolled blanks to ensure that no oxide skin and foreign matters fly into the laminated rolled blanks during rolling; coating and welding the upper steel plate and the lower steel plate to obtain a coated rolled bag, preferably, the inner side surface roughness of the upper steel plate and the lower steel plate is less than or equal to 1.5 mu m, and the upper steel plate and the lower steel plateThe lower steel plate has the same thickness T g0 Total thickness T of rolled and rolled blank t0 Respectively satisfy: t is g0 ≥T t0 ，T g0 For example, 15-20mm is selected; heating the clad rolling packet at 820-880 ℃ for 30-40min, and performing reverse hot rolling to obtain a clad rolling plate blank with the thickness of a single plate of 0.4-0.5 mm;
specifically, 2-pass reversing hot rolling is adopted, and single rolling is carried out along the width direction of a plate blank, wherein the deformation rate is alpha; rotating the plate blank by 90 degrees, and rolling the plate blank in a single time along the length direction of the plate blank, wherein the deformation rate beta is 75-85 percent, and the total deformation rate alpha + beta of the steel plate in the cladding rolling process is 75 percent; preferably, the ratio of the deformation rate alpha to the deformation rate beta is (35-40): (40-45);
the single rolling in the slab width direction satisfies formula (1):
H z1 ＝(1-α)T t0 +T g0 ×2×(1-λ×α) (1)
the single rolling along the length direction of the plate blank satisfies the formula (2):
wherein, before rolling, the total thickness T of the stacked titanium alloy rolled blanks t0 Thickness T of upper or lower steel plate g0 The steel titanium elongation ratio lambda, lambda value is about 1.04-1.08; clad-rolled package thickness H after single rolling along slab width direction z1 (ii) a Clad-rolled package thickness H after single rolling along slab length direction z2 By sequential detection of H z1 And H z2 Obtaining a wrapped and rolled plate blank with the thickness of 0.4-0.5 mm;
optionally, carrying out alkali pickling treatment and grinding wheel polishing treatment on the rolled plate blank; annealing the extremely-thin clad rolled plate blank, and releasing internal stress before cold rolling;
step seven: cold rolling, namely performing 1-pass cold rolling on the clad-rolled plate blank to obtain a cold-rolled plate blank with the deformation rate of less than 10%;
step eight: the step annealing treatment specifically comprises the following steps:
coating 4-6 cold-rolled plate blanks between an upper template and a lower template which are 4-6mm in thickness respectively; carrying out on-line heating by using a 50-100kW all-solid-state high-frequency induction heating device, wherein the heating rate is 300-500 ℃/min, the heating is carried out to 800-880 ℃, and the heat preservation time t and the total thickness h of the cold-rolled plate blank meet the following requirements: h x 10min is less than or equal to t is less than or equal to h x 15min;
after heat preservation, carrying out step cooling treatment, comprising the following steps:
s8.1: cooling the plate blank to 600 ℃ at the speed of not higher than 40 ℃/min;
s8.2: cooling the plate blank to 300 ℃ at a speed of not higher than 60 ℃/min;
s8.3: the slab is cooled to room temperature at a rate of not more than 100 deg.c/min.
Optionally, the finished plate after the step annealing treatment is subjected to alkali-acid washing treatment.
Among them, the alkali-acid washing treatment of the present invention preferably comprises the steps of:
A. alkali washing: soaking the plate blank in alkali melt liquid at 460-520 ℃ and carrying out alkali washing for 5-20 min; the alkali melt is composed of 85-95wt% NaOH and 5-15wt% NaNO 3 Composition is carried out;
B. primary acid washing: soaking the thin slab in a first acid solution at the temperature of below 60 ℃, pickling for less than 2min, and washing with water and drying; the first acid solution comprises: 5 to 15wt% of 2 SO 4 And the balance being water;
C. secondary acid washing: soaking the thin slab in a second acid solution at the temperature of below 60 ℃, and pickling for less than 10min; the second acid solution contains: 30 to 40wt% of HNO 3 4 to 5% wtHF and the balance water.
The grinding wheel grinding treatment, preferably adopting a diamond grinding wheel, comprises the following steps:
s1, coarse grinding: the granularity of the rough grinding wheel is 100-120 meshes, the rotating speed is 1200-1800r/min, the feeding amount is 0.02 mm-0.05 mm each time, and the feeding speed of the diamond grinding wheel is 800 mm/min-1000 mm/min;
s2, semi-fine grinding: the granularity of the semi-fine grinding wheel is 120-200 meshes, the rotating speed is 1500 r/min-2000 r/min, the feeding amount is 0.01 mm-0.02 mm each time, and the feeding speed is 500 mm/min-700 mm/min;
s3, fine grinding: the grain size of the fine grinding wheel is 200-300 meshes, the rotating speed is 3500 r/min-4000 r/min, the feeding amount is less than 0.01mm each time, and the feeding speed is 300 mm/min-450 mm/min.
By the preparation method, the ultrathin TC4 titanium alloy plate with the thickness as low as 0.4mm, the tensile strength of more than 1100MPa, the yield strength of more than 1000MPa, the elongation at break of more than 11 percent and the grain size of about 3 mu m can be obtained.
Example 1
Embodiment 1 provides a method for preparing an ultra-thin TC4 titanium alloy plate, including the steps of:
the method comprises the following steps: hot rolling and cogging, namely heating a titanium alloy blank with the thickness of 120mm at 960 +/-10 ℃ for 150min, and hot rolling to the thickness of 25mm; cutting into rough rolling blanks; grinding the rough rolling blank by using a grinding wheel;
step two: hot rolling with second fire, heating the rough rolling blank at 920 +/-10 ℃ for 40min, and performing 2-pass vertical reversing hot rolling to obtain a second fire plate blank with the thickness of 8 mm;
step three: heating the second fire plate blank at 1040 +/-20 ℃ for 25 minutes, and performing water quenching at 40 ℃;
step four: and (3) hot rolling, heating the plate blank obtained in the step (three) at the temperature of 920 +/-10 ℃ for 25min, and performing 2-pass reversing hot rolling, wherein the method comprises the following steps:
s4.1: adopting a different-speed asynchronous rolling mill to roll the plate blank in one time along the width direction of the plate blank, and the speed V of the upper roller 1 : lower roll speed V 2 Is 1.4;
s4.2: rotating the plate blank by 90 degrees, adopting a reducing asynchronous rolling mill to roll the plate blank in one time along the length direction of the plate blank, and obtaining the diameter R of an upper roller 1 : diameter of lower roller R 2 Is 1:1.2; obtaining three fire plate blanks with the thickness of 4mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the three-fire plate blank;
step five: double-sheet rolling, namely cutting three hot plate blanks into the same size, stacking and welding two hot plate blanks into a rolling pack in a group, heating the rolling pack at 900 +/-10 ℃ for 40min, and performing 2-pass reversing hot rolling, wherein the method comprises the following steps:
s5.1: rolling the pack in a single time along the width direction of the pack, and reducing the thickness of the pack to 6mm;
s5.2: rotating the plate blank by 90 degrees, and rolling the plate blank once along the length direction of the pack rolling ladle, wherein the thickness of the pack rolling ladle is reduced to 4mm;
s5.3: splitting the pack to obtain a pack-rolled plate blank with the thickness of 2 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the pack-rolled plate blank; cutting the plate blank into the same length and width;
step six: cladding and rolling the steel plates, stacking 4 pieces of stacked rolled blanks and fully welding the edges of the stacked rolled blanks; coating and welding an upper layer steel plate and a lower layer steel plate to obtain a coating rolling bag, wherein the roughness of the inner side surfaces of the upper layer steel plate and the lower layer steel plate is less than or equal to 1.5 mu m, and the thicknesses of the upper layer steel plate and the lower layer steel plate are respectively 15mm; heating the clad rolling packet at 840 +/-10 ℃ for 35min, and performing 2-pass reversing hot rolling, wherein the clad rolling packet is firstly rolled along the width direction of a plate blank; rotating the plate blank by 90 degrees, and rolling along the length direction to obtain a wrapped and rolled plate blank with the thickness of a single plate of 0.43 +/-0.01 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the rolled plate blank; annealing the extremely-thin clad rolled plate blank, and releasing internal stress before cold rolling;
step seven: cold rolling, namely performing 1-pass cold rolling on the plate blank subjected to the package rolling to obtain a cold-rolled plate blank with the thickness of 0.4mm, wherein the deformation rate is about 7.0%;
step eight: step annealing treatment, comprising:
coating 5 cold-rolled plate blanks between an upper template and a lower template which are respectively 4mm in thickness; carrying out on-line heating by using a 60kW all-solid-state high-frequency induction heating device, wherein the heating rate is 420 ℃/min, the heating is carried out for about 2min to 840 +/-10 ℃, and the heat preservation time is 25min;
after heat preservation, carrying out step cooling treatment, comprising the following steps:
s8.1: cooling the plate blank to 600 ℃ at the speed of 30 ℃/min;
s8.2: cooling the plate blank to 300 ℃ at the speed of 50 ℃/min;
s8.3: the slab was cooled to room temperature at a rate of 100 deg.C/min.
The total time of heating, heat preservation and cooling is less than 45min, and the ultrathin TC4 titanium alloy plate with the thickness of 0.4mm and uniform size is obtained.
Example 2
Embodiment 2 provides a method for preparing an ultra-thin TC4 titanium alloy plate, including:
the method comprises the following steps: hot rolling and cogging, namely heating a titanium alloy blank with the thickness of 120mm at 960 +/-10 ℃ for 150min, and hot rolling to the thickness of 25mm; cutting into rough rolling blanks; grinding the rough rolling blank by using a grinding wheel;
step two: hot rolling with second fire, heating the rough rolling blank at 920 +/-10 ℃ for 40min, and performing 2-pass vertical reversing hot rolling to obtain a second fire plate blank with the thickness of 10 mm;
step three: heating the second fire plate blank at 1040 +/-20 ℃ for 25 minutes, and performing water quenching at 40 ℃;
step four: and (3) hot rolling, heating the plate blank obtained in the step (three) at the temperature of 920 +/-10 ℃ for 30min, and performing 2-pass reversing hot rolling, wherein the method comprises the following steps:
s4.1: adopting a different-speed asynchronous rolling mill to roll the plate blank in one time along the width direction of the plate blank, and the speed V of the upper roller 1 : lower roll speed V 2 Is 1.3;
s4.2: rotating the plate blank by 90 degrees, adopting a reducing asynchronous rolling mill to roll the plate blank in a single time along the length direction of the plate blank, and measuring the diameter R of an upper roll 1 : diameter of lower roll R 2 Is 1:1.1; obtaining three fire plate blanks with the thickness of 4.5 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the three-fire plate blank;
step five: double-sheet rolling, namely cutting the three hot plate blanks into the same size, stacking and welding two hot plate blanks into a rolling pack, heating the rolling pack at 900 +/-10 ℃ for 40min, and performing 2-pass reversing hot rolling, wherein the method comprises the following steps of:
s5.1: rolling the pack in a single time along the width direction of the pack, and reducing the thickness of the pack to 7mm;
s5.2: rotating the plate blank by 90 degrees, and rolling the plate blank once along the length direction of the pack rolling ladle, wherein the thickness of the pack rolling ladle is reduced to 5mm;
s5.3: splitting the pack to obtain a pack-rolled plate blank with the thickness of a single sheet of 2.5 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the pack-rolled plate blank; cutting the plate blank into the same length and width dimensions;
step six: cladding and rolling the steel plate, stacking 6 pieces of overlapped rolling blanks and fully welding the edge part; carrying out cladding welding on an upper layer steel plate and a lower layer steel plate to obtain a cladding rolling bag, wherein the roughness of the inner side surfaces of the upper layer steel plate and the lower layer steel plate is less than or equal to 1.5 mu m, and the thicknesses of the upper layer steel plate and the lower layer steel plate are respectively 20mm; heating the clad rolling packet at 850 +/-10 ℃ for 40min, and performing 2-pass reversing hot rolling, wherein rolling is performed along the width direction of a plate blank; rotating the plate blank by 90 degrees, and rolling along the length direction to obtain a rolled plate blank with the thickness of the single plate of 0.46 +/-0.01 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the rolled plate blank; annealing the extremely-thin clad rolled plate blank, and releasing internal stress before cold rolling;
step seven: cold rolling, namely performing 1-pass cold rolling on the clad-rolled plate blank to obtain a cold-rolled plate blank with the thickness of 0.44mm, wherein the deformation rate is about 4.3%;
step eight: step annealing treatment, comprising:
coating 5 cold-rolled plate blanks between an upper template and a lower template which are respectively 5mm in thickness; carrying out on-line heating by using a 60kW all-solid-state high-frequency induction heating device, wherein the heating rate is 420 ℃/min, the heating is carried out for about 2min to 840 +/-10 ℃, and the heat preservation time is 26min;
after heat preservation, carrying out step cooling treatment, comprising the following steps:
s8.1: cooling the plate blank to 600 ℃ at the speed of 30 ℃/min;
s8.2: cooling the plate blank to 300 ℃ at the speed of 50 ℃/min;
s8.3: the slab was cooled to room temperature at a rate of 100 deg.C/min.
The total time of heating, heat preservation and cooling is less than 45min, and the ultrathin TC4 titanium alloy plate with the thickness of 0.44mm and uniform size is obtained.
Example 3
Embodiment 3 provides a method for preparing an ultra-thin TC4 titanium alloy plate, including:
the method comprises the following steps: hot rolling and cogging, namely heating a titanium alloy blank with the thickness of 120mm at 960 +/-10 ℃ for 150min, and hot rolling to the thickness of 30mm; cutting into rough rolling blanks; grinding the rough rolling blank by using a grinding wheel;
step two: carrying out hot rolling on two heats, heating the rough rolling blank at 920 +/-10 ℃ for 40min, and carrying out 2-pass vertical reversing hot rolling to obtain a two-heat plate blank with the thickness of 12 mm;
step three: heating the second fire plate blank at 1040 +/-20 ℃ for 25 minutes, and quenching the second fire plate blank in water at 40 ℃;
step four: and (3) hot rolling, heating the plate blank obtained in the step (three) at the temperature of 920 +/-10 ℃ for 30min, and performing 2-pass reversing hot rolling, wherein the method comprises the following steps:
s4.1: adopting a different-speed asynchronous rolling mill to roll the plate blank in one time along the width direction of the plate blank, and the speed V of the upper roller 1 : lower roll speed V 2 Is 1.3;
s4.2: rotating the plate blank by 90 degrees, adopting a reducing asynchronous rolling mill to roll the plate blank in one time along the length direction of the plate blank, and obtaining the diameter R of an upper roller 1 : diameter of lower roll R 2 Is 1:1.1; obtaining three fire plate blanks with the thickness of 5mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the three-fire plate blank;
step five: double-sheet rolling, namely cutting three hot plate blanks into the same size, stacking and welding two hot plate blanks into a rolling pack in a group, heating the rolling pack at 900 +/-10 ℃ for 40min, and performing 2-pass reversing hot rolling, wherein the method comprises the following steps:
s5.1: rolling the pack in a single time along the width direction of the pack, and reducing the thickness of the pack to 7mm;
s5.2: rotating the plate blank by 90 degrees, and rolling the plate blank once along the length direction of the pack, wherein the thickness of the pack is reduced to 5mm;
s5.3: splitting the pack to obtain a pack-rolled plate blank with the thickness of a single sheet of 2.5 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the rolled plate blank; cutting the plate blank into the same length and width dimensions;
step six: cladding and rolling the steel plates, stacking 8 pieces of stacked rolled blanks and fully welding the edges of the stacked rolled blanks; carrying out cladding welding on an upper layer steel plate and a lower layer steel plate to obtain a cladding rolling bag, wherein the roughness of the inner side surfaces of the upper layer steel plate and the lower layer steel plate is less than or equal to 1.5 mu m, and the thicknesses of the upper layer steel plate and the lower layer steel plate are respectively 20mm; heating the clad rolling packet at 850 +/-10 ℃ for 40min, and performing 2-pass reversing hot rolling, wherein the clad rolling packet is firstly rolled along the width direction of a plate blank; rotating the plate blank by 90 degrees, and rolling along the length direction to obtain a wrapped and rolled plate blank with the thickness of about 0.5 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the rolled plate blank; annealing the extremely thin plate blank to release internal stress before cold rolling;
step seven: cold rolling, namely performing 1-pass cold rolling on the plate blank subjected to the package rolling to obtain a cold-rolled plate blank with the thickness of 0.49mm, wherein the deformation rate is about 2%;
step eight: step annealing treatment, comprising:
coating 4 cold-rolled plate blanks between an upper template and a lower template which are respectively 6mm in thickness; carrying out on-line heating by using a 70kW all-solid-state high-frequency induction heating device, wherein the heating rate is 430 ℃/min, the heating is carried out for about 2min to 860 +/-10 ℃, and the heat preservation time is 25min;
after heat preservation, carrying out step cooling treatment, comprising the following steps:
s8.1: cooling the plate blank to 600 ℃ at the speed of 40 ℃/min;
s8.2: cooling the plate blank to 300 ℃ at the speed of 50 ℃/min;
s8.3: the slab was cooled to room temperature at a rate of 100 deg.C/min.
The total time of temperature rise, heat preservation and temperature reduction is less than 45min, and the ultrathin TC4 titanium alloy plate with the thickness of 0.49mm and uniform size is obtained.
Comparative example 1
The difference between the comparative example and the example 1 is that the double-sheet pack rolling and the subsequent steps are carried out after the hot rolling and the second fire, and the method specifically comprises the following steps:
the method comprises the following steps: hot rolling and cogging, namely heating the titanium alloy blank with the thickness of 120mm at 960 +/-10 ℃ for 150min, and hot rolling to the thickness of 25mm; cutting into rough rolling blanks; grinding the rough rolling blank by using a grinding wheel;
step two: hot rolling with second fire, heating the rough rolling blank at 920 +/-10 ℃ for 40min, and performing 2-pass vertical reversing hot rolling to obtain a second fire plate blank with the thickness of 4mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the second fire plate blank;
step three: double-sheet rolling, namely cutting the two hot plate blanks into the same size, stacking and welding the two hot plate blanks into a rolling pack in a group, heating the rolling pack at 900 +/-10 ℃ for 40min, and performing 2-pass reversing hot rolling, wherein the method comprises the following steps:
s3.1: rolling the pack in a single time along the width direction of the pack, and reducing the thickness of the pack to 6mm;
s3.2: rotating the plate blank by 90 degrees, and rolling the plate blank once along the length direction of the pack rolling ladle, wherein the thickness of the pack rolling ladle is reduced to 4mm;
s3.3: splitting the pack to obtain a pack-rolled plate blank with the thickness of 2 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the pack-rolled plate blank; cutting the plate blank into the same length and width dimensions;
step four: cladding and rolling the steel plate, stacking 4 pieces of overlapped rolling blanks and fully welding the edges of the overlapped rolling blanks; carrying out cladding welding on an upper layer steel plate and a lower layer steel plate to obtain a cladding rolling bag, wherein the roughness of the inner side surfaces of the upper layer steel plate and the lower layer steel plate is less than or equal to 1.5 mu m, and the thicknesses of the upper layer steel plate and the lower layer steel plate are respectively 15mm; heating the clad rolling packet at 840 +/-10 ℃ for 35min, and performing 2-pass reversing hot rolling, wherein rolling is performed along the width direction of a plate blank; rotating the plate blank by 90 degrees, and rolling along the length direction to obtain a wrapped and rolled plate blank with the thickness of the single plate of 0.43 +/-0.01 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the rolled plate blank; annealing the extremely-thin clad rolled plate blank, and releasing internal stress before cold rolling;
step five: cold rolling, namely performing 1-pass cold rolling on the rolled plate blank to obtain a cold-rolled plate blank with the thickness of 0.4mm, wherein the deformation rate is about 7.0%;
step six: step annealing treatment, comprising:
coating 5 cold-rolled plate blanks between an upper template and a lower template which are respectively 4mm in thickness; carrying out on-line heating by using a 60kW all-solid-state high-frequency induction heating device, wherein the heating rate is 420 ℃/min, the heating is carried out for about 2min to 840 +/-10 ℃, and the heat preservation time is 25min;
after heat preservation, carrying out step cooling treatment, comprising the following steps:
s6.1: cooling the plate blank to 600 ℃ at the speed of 30 ℃/min;
s6.2: cooling the plate blank to 300 ℃ at the speed of 50 ℃/min;
s6.3: the slab was cooled to room temperature at a rate of 100 deg.C/min.
The total time of heating, heat preservation and cooling is less than 45min, and the titanium alloy plate with the thickness of 0.4mm is obtained.
Comparative example 2
The comparative example differs from example 1 in that the double sheet pack rolling step is omitted, and specifically comprises the following steps:
the method comprises the following steps: hot rolling and cogging, namely heating a titanium alloy blank with the thickness of 120mm at 960 +/-10 ℃ for 150min, and hot rolling to the thickness of 25mm; cutting into rough rolling blanks; grinding the rough rolling blank by using a grinding wheel;
step two: carrying out hot rolling on two heats, heating the rough rolling blank at 920 +/-10 ℃ for 40min, and carrying out 2-pass vertical reversing hot rolling to obtain a two-heat plate blank with the thickness of 8 mm;
step three: heating the second fire plate blank at 1040 +/-20 ℃ for 25 minutes, and performing water quenching at 40 ℃;
step four: and (3) hot rolling, heating the plate blank obtained in the step (three) at the temperature of 920 +/-10 ℃ for 25min, and performing 2-pass reversing hot rolling, wherein the method comprises the following steps:
s4.1: adopting a different-speed asynchronous rolling mill to roll the plate blank in one time along the width direction of the plate blank, and the speed V of the upper roller 1 : lower roll speed V 2 Is 1.5;
s4.2: rotating the plate blank by 90 degrees, adopting a reducing asynchronous rolling mill to roll the plate blank in one time along the length direction of the plate blank, and obtaining the diameter R of an upper roller 1 : diameter of lower roller R 2 Is 1:1.3; obtaining a three-fire plate blank with the thickness of 3.5 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the three-fire plate blank; cutting the plate blank into the same length and width dimensions;
step five: cladding and rolling the steel plates, stacking 4 pieces of stacked rolled blanks and fully welding the edges of the stacked rolled blanks; carrying out cladding welding on an upper layer steel plate and a lower layer steel plate to obtain a cladding rolling bag, wherein the roughness of the inner side surfaces of the upper layer steel plate and the lower layer steel plate is less than or equal to 1.5 mu m, and the thicknesses of the upper layer steel plate and the lower layer steel plate are respectively 20mm; heating the clad rolling packet at 840 +/-10 ℃ for 35min, and performing 2-pass reversing hot rolling, wherein the clad rolling packet is firstly rolled along the width direction of a plate blank; rotating the plate blank by 90 degrees, and rolling along the length direction to obtain a wrapped and rolled plate blank with the thickness of a single plate of 0.43 +/-0.02 mm;
carrying out alkali pickling treatment and grinding wheel polishing treatment on the rolled plate blank; annealing the extremely-thin clad rolled plate blank, and releasing internal stress before cold rolling;
step six: cold rolling, namely performing 1-pass cold rolling on the rolled plate blank to obtain a cold-rolled plate blank with the thickness of 0.4mm, wherein the deformation rate is about 7.0%;
step seven: step annealing treatment, comprising:
coating 5 cold-rolled plate blanks between an upper template and a lower template which are respectively 4mm in thickness; carrying out on-line heating by using a 60kW all-solid-state high-frequency induction heating device, wherein the heating rate is 420 ℃/min, the heating is carried out for about 2min to 840 +/-10 ℃, and the heat preservation time is 25min;
after heat preservation, carrying out step cooling treatment, comprising the following steps:
s7.1: cooling the plate blank to 600 ℃ at the speed of 30 ℃/min;
s7.2: cooling the plate blank to 300 ℃ at the speed of 50 ℃/min;
s7.3: the slab was cooled to room temperature at a rate of 100 deg.C/min.
The total time of temperature rise, heat preservation and temperature reduction is less than 45min, and the titanium alloy plate with the thickness of 0.4mm is obtained.
Comparative example 3
This comparative example was identical to example 1 in the rolling process and yielded a finished sheet of 0.4mm thickness, except that the step annealing in step eight was replaced by the usual annealing method (heating the slab to 840 ℃ and holding it for 1-2 hrs and then air-cooling).
The room temperature mechanical properties of examples 1 to 3 and comparative examples 1 to 3 were tested. The test results are shown in table 1:
TABLE 1 test results of examples 1-3 and comparative examples 1-3
As can be seen from Table 1, the samples of examples 1-3 have tensile strength at room temperature of over 1100MPa, yield strength of over 1000MPa, elongation at break of over 11%, grain size of within 5 μm, and good strength and plasticity. Comparative example 1 omits the heating quenching after the second heat of hot rolling and the third heat of hot rolling, the lack of the solid solution process causes the insufficient dispersion strengthening effect in the subsequent processing process, and simultaneously causes the insufficient grain refinement and the insufficient tissue uniformity, even if the thickness of the sheet is reduced to 0.4mm and the annealing treatment is carried out by the subsequent process, the grains in the sheet are relatively coarse and uneven, the microscopic defects are more, and the macroscopic mechanical property is poorer. Comparative example 2 omits double-sheet pack rolling, resulting in a slightly lower uniformity of the thickness of the plate blank subjected to steel plate cladding rolling, higher deformation rate of the steel plate cladding rolling, lower uniformity of microstructure and macro thickness, larger internal stress of the plate, and a certain relief after subsequent cold rolling annealing and other treatments, but the comprehensive performance is still reduced to a certain extent compared with the embodiment. Comparative example 3 changes the step annealing treatment to the conventional annealing treatment, and the annealing efficiency is low, the internal stress of the plate is released unevenly, the limitation of the template is avoided, and the thickness uniformity and the evenness of the plate are slightly low.
In general, the ultrathin TC4 titanium alloy plate prepared by the invention can meet and is obviously superior to the requirement of the aviation material standard specification AMS 4911, and has wide prospect in the fields of high standards such as aerospace and high added value.
The average grain size of the samples of examples 1-3 is below 5 μm, and fig. 1 is a transmission electron microscope bright field image (a) and dark field image (b) picture of the sample of example 1, wherein the grain size of the sample is below 3.5 μm and has relatively uniform size, and the grain size is basically distributed in the range of 2.8-3.5 μm.
The thickness measurement was performed by taking 6 measurement points for the samples of example 1 and comparative examples 1 to 3, and the same plate difference (unit: mm) was calculated, and the specific numbers are shown in Table 2:
table 2 thickness test results of example 1 and comparative examples 1 to 3
As shown in Table 2, the titanium alloy sheet prepared in example 1 has a same sheet difference of 0.010mm, has good thickness uniformity, does not need subsequent correction or finishing procedures, and has short correction time and good effect. Comparative examples 1 and 2 were insufficient due to the previous treatment, and although they were subjected to the final step annealing treatment, the thickness uniformity was slightly insufficient. While comparative example 3 employs annealing means conventional in the art, it is not only relatively time consuming, but also has significantly less thickness uniformity than the previous examples and comparative examples.
The foregoing describes preferred embodiments of the present invention, and is intended to make the spirit and scope of the present invention clear and understandable, but not to limit the present invention, and modifications, substitutions and improvements made within the spirit and principle of the present invention are included in the scope of the present invention as outlined by the appended claims.
Claims (10)
1. The preparation method of the ultrathin TC4 titanium alloy plate is characterized by comprising the following steps of:
the method comprises the following steps: hot rolling and cogging, heating the titanium alloy blank at 920-1000 ℃ for 120-180min, and hot rolling to the thickness of 25-35mm; cutting into rough rolling blanks;
step two: hot rolling with two heats, heating the rough rolling blank at 900-950 ℃ for 30-50min, reversing hot rolling to obtain a two-heat plate blank with the thickness of 8-12 mm;
step three: heating the second fire plate blank at 1040 +/-20 ℃ for 20-30 minutes, and water quenching;
step four: hot rolling with three fires, heating the plate blank obtained in the step three at 900-950 ℃ for 20-30min, reversing hot rolling to obtain a three-fire plate blank with the thickness of 4-5mm;
step five: double-sheet pack rolling, namely stacking the three hot plate blanks in a mode of two sheets in a group and welding the stacked plate blanks into a pack roll pack, and rolling to obtain a pack rolled plate blank with the thickness of a single sheet of 2-2.5 mm;
step six: cladding and rolling a steel plate, and stacking and welding a plurality of the stacked rolled blanks; carrying out cladding welding on the upper layer steel plate and the lower layer steel plate to obtain a cladding rolling packet; heating the clad rolling packet at 820-880 ℃ for 30-40min, and performing reverse hot rolling to obtain a clad rolling plate blank with the thickness of a single plate of 0.4-0.5 mm;
step seven: cold rolling, namely performing 1-pass cold rolling on the clad-rolled plate blank to obtain a cold-rolled plate blank with the deformation rate of less than 10%;
step eight: and (5) step annealing treatment.
2. The manufacturing method according to claim 1, wherein at least one of the three fire slabs, the pack rolled slab and the pack rolled slab is subjected to an alkali pickling process, wherein the alkali pickling process includes the steps of:
A. alkali washing: soaking the plate blank in alkali melt liquid at 460-520 ℃ and carrying out alkali washing for 5-20 min; said alkali melt is composed of 85-95wt% NaOH and 5-15wt% NaNO 3 Forming;
B. primary acid washing: soaking the thin slab in a first acid solution at the temperature of below 60 ℃, pickling for less than 2min, and washing with water and drying; the first acid solution contains: 5 to 15wt.% of 2 SO 4 And the balance being water;
C. secondary acid washing: soaking the thin slab in a second acid solution at the temperature of below 60 ℃, and pickling for less than 10min; the second acid solution contains: 30 to 40wt% of HNO 3 4-5% wtHF and the balance water.
3. The manufacturing method according to claim 2, wherein the slab subjected to the alkali-acid washing treatment is subjected to a grinding wheel grinding treatment using a diamond grinding wheel, comprising the steps of:
s1, coarse grinding: the granularity of the rough grinding wheel is 100-120 meshes, the rotating speed is 1200-1800r/min, the feeding amount is 0.02 mm-0.05 mm each time, and the feeding speed of the diamond grinding wheel is 800 mm/min-1000 mm/min;
s2, semi-fine grinding: the granularity of the semi-fine grinding wheel is 120-200 meshes, the rotating speed is 1500 r/min-2000 r/min, the feeding amount is 0.01 mm-0.02 mm each time, and the feeding speed is 500 mm/min-700 mm/min;
s3, fine grinding: the grain size of the fine grinding wheel is 200-300 meshes, the rotating speed is 3500 r/min-4000 r/min, the feeding amount is less than 0.01mm each time, and the feeding speed is 300 mm/min-450 mm/min.
4. The method according to any one of claims 1 to 3, wherein in the second step, 2-pass vertical reversing hot rolling is performed, and the deformation rate is 60 to 75%, and comprises:
s2.1: single rolling along the width direction of the plate blank;
s2.2: the slab is rotated by 90 degrees and rolled in a single time along the length direction of the slab.
5. The method of claim 4, wherein in step four, 2 passes of reverse hot rolling are performed, comprising the steps of:
s4.1: adopting a different-speed asynchronous rolling mill to roll the plate blank in one time along the width direction of the plate blank, and the speed V of the upper roller 1 : lower roll speed V 2 1.2-1.5;
s4.2: rotating the plate blank by 90 degrees, adopting a reducing asynchronous rolling mill to roll the plate blank in one time along the length direction of the plate blank, and obtaining the diameter R of an upper roller 1 : diameter of lower roller R 2 Is 1: (1.1-1.3).
6. The preparation method of claim 5, wherein in the fifth step, the pack-rolled steel is heated at 900 +/-20 ℃ for 30-40min and subjected to 2-pass reverse hot rolling, and the method comprises the following steps:
s5.1: rolling the pack in a single time along the width direction of the pack, and reducing the thickness of the pack to 6-7mm;
s5.2: rotating the plate blank by 90 degrees, and rolling the plate blank once along the length direction of the pack rolling ladle, wherein the thickness of the pack rolling ladle is reduced to 4-5mm;
s5.3: splitting the pack to obtain a pack-rolled plate blank with the thickness of a single sheet of 2-2.5 mm.
7. The production method according to claim 5 or 6, wherein in the cladding rolling of the steel sheet in the sixth step, 4 to 8 pieces of the clad rolled steel sheet are stacked and edge-full welded before the rolling, the inner side surface roughness of the upper steel sheet and the lower steel sheet is 1.5 μm or less, and the thickness T of the upper steel sheet and the lower steel sheet is 1.5 μm or less g0 Total thickness T of rolled and rolled blank t0 Respectively satisfy: t is g0 ≥T t0 。
8. The production method according to claim 7, wherein the clad-rolling of the steel sheet is performed by 2-pass reverse hot rolling, and the steel sheet is subjected to single rolling in the width direction of the slab at a deformation ratio α; rotating the plate blank by 90 degrees, and rolling the plate blank in a single time along the length direction of the plate blank, wherein the deformation rate beta and the total deformation rate alpha + beta of the steel plate cladding rolling are 75-85 percent;
the single rolling in the slab width direction satisfies formula (1):
H z1 ＝(1-α)T t0 +T g0 ×2×(1-λ×α) (1)
the single rolling along the length direction of the plate blank satisfies the formula (2):
wherein, before rolling, the total thickness T of the stacked titanium alloy rolled blanks t0 Thickness T of upper or lower steel plate g0 Steel-to-titanium elongation ratio λ; clad-rolled packet thickness H after single rolling in slab width direction z1 (ii) a Clad-rolled package thickness H after single rolling along slab length direction z2 By sequential detection of H z1 And H z2 And obtaining the clad rolling plate blank with the veneer thickness of 0.4-0.5 mm.
9. The manufacturing method according to claim 7, wherein in the eighth step, 4 to 6 cold-rolled slabs are clad between an upper die plate and a lower die plate each having a thickness of 4 to 6mm; performing on-line heating by using a 50-100kW all-solid-state high-frequency induction heating device, wherein the heating rate is 300-500 ℃/min, the heating is performed to 800-880 ℃, and the heat preservation time t and the total thickness h of the cold-rolled plate blank meet the following requirements: t is more than or equal to h multiplied by 10min and less than or equal to h multiplied by 15min.
10. The method according to claim 9, wherein the step-wise cooling treatment is performed after the holding time t, and comprises the steps of:
s8.1: cooling the plate blank to 600 ℃ at the speed of not higher than 40 ℃/min;
s8.2: cooling the plate blank to 300 ℃ at a speed of not higher than 60 ℃/min;
s8.3: the slab is cooled to room temperature at a rate of not more than 100 deg.C/min.
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