A method for preparing high-strength, corrosion-resistant, fine-grained titanium alloy plate

Abstract

The present invention discloses a method for preparing a high-strength, corrosion-resistant, fine-grained titanium alloy plate, belonging to the technical field of high-strength, corrosion-resistant material preparation. The high-strength, corrosion-resistant TC4 titanium alloy described in the present invention comprises, by mass percentage, 5.5-6.5% Al, 3.7-4.2% V, 0.8-1.2% La, 0.03-0.05% Ce, 0.02-0.04% Pr, and 0.01-0.02% Yb, with the remainder being Ti and trace impurity elements. The finished material preparation method includes gas atomization treatment, pressing, sintering, pre-aging treatment, asynchronous cold rolling treatment, multi-stage solution treatment, quenching, and artificial aging treatment. The resulting high-strength, corrosion-resistant, fine-grained titanium alloy plate has excellent strength, toughness, and corrosion resistance. The workpieces thereof can be used in aerospace or marine engineering, and have excellent industrial application prospects.

Description

Technical Field

[0001] The invention relates to a method for preparing a high-strength, corrosion-resistant, fine-grained titanium alloy plate, and belongs to the technical field of preparing high-strength, high-toughness, corrosion-resistant titanium alloys. Background Art

[0002] TC4 titanium alloy, also known as Ti-6Al-4V, is a titanium alloy widely used in aerospace, automotive, chemical, and marine applications. It exhibits high strength, good corrosion resistance, low density, and excellent overall mechanical properties. The manufacturing and processing technologies of TC4 titanium alloy have long been a hot topic in materials science research.

[0003] Chinese invention patent CN118531342A introduces a process for improving the surface strength and corrosion resistance of metal materials. The process mainly uses surface modification technology to nitriding the surface of TC4 titanium alloy material to form a nitrided layer, thereby improving the corrosion resistance of the material to a certain extent. However, due to the long production cycle, high cost and difficult post-processing of nitriding treatment, it is not conducive to actual production application.

[0004] Chinese invention patent CN118291810A introduces a new type of high-strength, corrosion-resistant titanium alloy and its preparation method. Other elements are added through alloy smelting. This process is prone to adding other impurity elements, thereby affecting the microstructure of the alloy.

[0005] Therefore, it is necessary to provide a method for preparing high-strength, corrosion-resistant, fine-grained titanium alloy plates, strengthen the strength of the surface of the titanium alloy plates, and improve the protective effect and duration of the surface corrosion resistance. Summary of the Invention

[0006] In order to overcome the problems in the background technology, the present invention adds rare earth elements through the atomization method, so that the synthesized sample powder has a higher purity, avoiding the influence of other impurity elements on the microstructure and performance, and then combines asynchronous rolling, multi-stage solid solution treatment, quenching and aging treatment to form a high-density multi-level dislocation structure, so that the solute atoms are evenly distributed, the bonding strength between the precipitated phase and the matrix is ​​improved, the strength and corrosion resistance of the plate are greatly improved, and the application of titanium alloy materials in aerospace, automobile, marine engineering and other fields is further expanded.

[0007] To achieve the above object, the present invention is implemented by the following technical solution: by adding rare earth elements (La, Ce, Pr and Yb) and adopting inert gas atomization, pressing, sintering, preheating treatment, asynchronous rolling, high temperature solution treatment, quenching, aging treatment and other processes to obtain the required strong and wear-resistant texture, specifically comprising the following steps:

[0008] (1) Gas atomization treatment: The prepared rare earth raw materials and TC4 alloy raw materials are mixed by inert gas atomization treatment.

[0009] (2) The prepared titanium alloy powder is subjected to pressing and sintering, pre-aging treatment, asynchronous cold rolling treatment, solution treatment, and quenching treatment in sequence.

[0010] (3) The samples were then artificially aged at a temperature of 400-420°C for 4 h and then air-cooled to room temperature.

[0011] Furthermore, the titanium alloy described in the present invention mainly contains 5.5-6.5% Al, 3.7-4.2% V, 0.8-1.2% La, 0.03-0.05% Ce, 0.02-0.04% Pr, 0.01-0.02% Yb, and the remainder is Ti and some inevitable impurity elements; the present invention can refine the grains and reduce defects in the processing process in the later treatment by adding trace rare earth elements at the same time, thereby improving the strength of the alloy.

[0012] Preferably, the gas atomization treatment conditions of the present invention are as follows: the induction power reaches 60kW, the atomization pressure is 6.0MPa; argon is introduced into the inert gas to prevent the titanium alloy from reacting with oxygen at high temperature; the melting temperature is 1750-1800°C, the atomization pressure is about 6.0MPa, and the gas flow rate is 60-80m 3 / h.

[0013] Preferably, in the pressing and sintering of the present invention, the titanium alloy powder is pressed into a plate and then sintered at a temperature of 1150-1300° C. for 2 hours.

[0014] Preferably, the parameters of the pre-annealing treatment of the present invention are: 300-350° C. for 2 hours.

[0015] Preferably, the conditions for the asynchronous cold rolling treatment of the present invention are: during asynchronous cold rolling, the speed ratio of the upper and lower rollers is 1.2, the total pressing amount of the sample is 50%, the number of pressing times is 10 times, and the pressing amount each time is not less than 5%.

[0016] Preferably, in step (2) of the present invention, a multi-stage solution treatment is performed, wherein the solution temperature of the first stage is 850°C and the insulation time is 2 hours; the solution temperature of the second stage is 900°C and the insulation time is 2 hours; and the solution temperature of the third stage is 950°C and the insulation time is 2 hours.

[0017] Preferably, during the artificial aging treatment in step (5) of the present invention, the aging temperature is 400-420° C. and the insulation time is 4 hours.

[0018] Beneficial effects of the present invention:

[0019] (1) The present invention reduces the dependence on and the amount of addition of a single rare earth element by adding a reasonable ratio of multiple rare earth elements, thereby reducing costs and reducing the consumption of specific rare earth resources; there is a synergistic effect between different rare earth elements, and through appropriate heat treatment processes, the strengthening effect of rare earth elements can be further exerted, promoting the formation of precipitation phases, thereby improving the strength and corrosion resistance of the alloy.

[0020] (2) Through solution aging treatment, rare earth elements are stimulated to improve the interfacial bonding strength between the precipitated phase and the matrix titanium, and the combination of Ce, Pr and Yb can more effectively enhance this interfacial bonding; Ce and La can combine with oxygen to form stable oxides, reducing oxidation in the alloy and improving the corrosion resistance of the alloy; the co-addition of La, Ce and Yb rare earth elements can more effectively consume harmful solute atoms during the solution process, thereby reducing grain boundary embrittlement and improving the strength of the alloy.

[0021] (3) In the present invention, the asynchronous cold rolling method is adopted, which can reduce the deformation resistance of the material and improve the deformation degree compared with ordinary cold rolling; at the same time, it can promote the formation of twin boundaries in the material and improve the plasticity and toughness of the titanium alloy.

[0022] (4) The multi-stage solution treatment used in the present invention allows the asynchronously cold-rolled alloy to be kept at a temperature of 850°C, so that most of the eutectic phase dissolves back into the matrix. When the temperature reaches 900°C, the eutectic structure begins to show anisotropy. Finally, when the temperature reaches 950°C, the grains are recrystallized, and the grains are uniformly refined to obtain a fine equiaxed α phase + β phase structure, thereby greatly improving the strength and corrosion resistance of the alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flowchart of the present invention.

[0024] Figure 2 This is a schematic diagram of part of the production process of the high-strength, corrosion-resistant, fine-grained titanium alloy plate of the present invention. Specific implementation plan

[0025] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention is further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0026] Example 1

[0027] The chemical composition of the high-strength, corrosion-resistant, fine-grained titanium alloy plate implemented in the present invention is shown in Table 1.

[0028] Table 1 Chemical composition (wt%) of high-strength, corrosion-resistant, fine-grained titanium alloy plate according to a specific embodiment of the present invention

[0029] A1 V La Ce Pr Yb margin 5.7 3.8 1.0 0.05 0.04 0.02 Ti and inevitable impurities

[0030] The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate described in this embodiment specifically includes the following steps:

[0031] (1) The alloy was subjected to gas atomization treatment according to the composition in Table 1. The prepared rare earth raw materials and titanium alloy raw materials were gas atomized and mixed separately. The gas flow rate was 60m 3 / h, the gas pressure is 1.6MPa, the melting temperature is 1800℃, and then the two are fully mixed during atomization, and react in an inert gas nitrogen atmosphere to form fine spherical powder particles.

[0032] (2) The alloy powder obtained in step (1) was mixed evenly and pressed into a rectangular billet of 50 mm × 50 mm × 20 mm using a hydraulic press at a pressure of 300 MPa and a holding time of 5 min.

[0033] (3) The blank obtained in step (2) is placed in a vacuum sintering furnace for heating and sintering. The blank is heated to 1200°C at a rate of 60°C / min and sintered for 2 hours to obtain the desired sample.

[0034] (4) The alloy sample in step (3) was subjected to a pre-annealing treatment at 300°C for 2 hours to reduce the internal stress, and an asynchronous cold rolling process was performed, with the speed ratio of the upper and lower rollers being 1.2, the total pressing amount of the sample being 50%, the number of pressing times being 10, and the pressing amount each time being not less than 5%.

[0035] (5) The alloy sample obtained by asynchronous rolling in step (4) was subjected to a multi-stage solution treatment, wherein the first stage solution temperature was 850°C and the holding time was 2 hours; the second stage solution temperature was 900°C and the holding time was 2 hours; the third stage solution temperature was 950°C and the holding time was 2 hours; followed by water cooling quenching for 5 minutes; and finally artificial aging treatment was performed at 400°C and the holding time was 4 hours. The yield strength, tensile strength and elongation of the alloy were measured to be 970.2 MPa, 1175.4 MPa and 17.7%.

[0036] Example 2

[0037] The chemical composition of the high-strength, corrosion-resistant, fine-grained titanium alloy plate implemented in the present invention is shown in Table 1.

[0038] Table 2 Chemical composition (wt%) of high-strength, corrosion-resistant, fine-grained titanium alloy plate according to a specific embodiment of the present invention

[0039] Al V La Ce Pr Yb margin 6.2 4.1 1.2 0.03 0.02 0.01 Ti and inevitable impurities

[0040] The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate described in this embodiment specifically includes the following steps:

[0041] (1) The alloy was subjected to gas atomization treatment according to the composition in Table 2. The prepared rare earth raw materials and titanium alloy raw materials were gas atomized and mixed separately. The gas flow rate was 80m 3 / h, the gas pressure is 1.6MPa, the melting temperature is 1800℃, and then the two are fully mixed during atomization, and react in an inert gas nitrogen atmosphere to form fine spherical powder particles.

[0042] (2) The alloy powder obtained in step (1) was mixed evenly and pressed into a rectangular billet of 50 mm × 50 mm × 20 mm using a hydraulic press at a pressure of 300 MPa and a holding time of 5 min.

[0043] (3) The blank obtained in step (2) is placed in a vacuum sintering furnace for heating and sintering. The blank is heated to 1150°C at a rate of 60°C / min and sintered for 2 hours to obtain the desired sample.

[0044] (4) The alloy sample in step (3) was subjected to a pre-annealing treatment at 340°C for 2 h to reduce the internal stress, and an asynchronous cold rolling treatment was performed, with the speed ratio of the upper and lower rollers being 1.2, the total pressing amount of the sample being 50%, the number of pressing times being 10, and the pressing amount each time being not less than 5%.

[0045] (5) The alloy sample obtained by asynchronous rolling in step (4) was subjected to a multi-stage solution treatment, wherein the first stage solution temperature was 850°C and the holding time was 2 hours; the second stage solution temperature was 900°C and the holding time was 2 hours; the third stage solution temperature was 950°C and the holding time was 2 hours; followed by water cooling quenching for 5 minutes; and finally artificial aging treatment was performed at an aging temperature of 420°C and the holding time was 4 hours. The yield strength, tensile strength and elongation of the alloy were measured to be 953.2 MPa, 1146.7 MPa and 15.4%.

[0046] Example 3

[0047] The chemical composition of the high-strength, corrosion-resistant, fine-grained titanium alloy plate implemented in the present invention is shown in Table 3.

[0048] Table 3 Chemical composition (wt%) of high-strength, corrosion-resistant, fine-grained titanium alloy plate according to a specific embodiment of the present invention

[0049] Al V La Ce Pr Yb margin 6.5 3.7 0.8 0.04 0.03 0.02 Ti and inevitable impurities

[0050] The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate described in this embodiment specifically includes the following steps:

[0051] (1) The alloy was subjected to gas atomization treatment according to the composition in Table 3. The prepared rare earth raw materials and titanium alloy raw materials were gas atomized and mixed respectively. The gas flow rate was 70m 3 / h, the gas pressure is 1.6MPa, the melting temperature is 1750℃, and then the two are fully mixed during atomization and react in an inert gas nitrogen atmosphere to form fine spherical powder particles.

[0052] (2) The alloy powder obtained in step (1) was mixed evenly and pressed into a rectangular billet of 50 mm × 50 mm × 20 mm using a hydraulic press at a pressure of 300 MPa and a holding time of 5 min.

[0053] (3) The blank obtained in step (2) is placed in a vacuum sintering furnace for heating and sintering. The blank is heated to 1250°C at a rate of 60°C / min and sintered for 2 hours to obtain the desired sample.

[0054] (4) The alloy sample in step (3) was subjected to a pre-annealing treatment at 350°C for 2 h to reduce the internal stress, and an asynchronous cold rolling treatment was performed, with the speed ratio of the upper and lower rollers being 1.2, the total pressing amount of the sample being 50%, the number of pressing times being 10, and the pressing amount each time being not less than 5%.

[0055] (5) The alloy sample obtained by asynchronous rolling in step (4) was subjected to a multi-stage solution treatment, wherein the first stage solution temperature was 850°C and the holding time was 2 hours; the second stage solution temperature was 900°C and the holding time was 2 hours; the third stage solution temperature was 950°C and the holding time was 2 hours, followed by water cooling quenching for 5 minutes; finally, artificial aging treatment was performed, with the aging temperature being 410°C and the holding time being 4 hours; the yield strength, tensile strength and elongation of the alloy were measured to be 967.8 MPa, 1166.8 MPa and 16.1%.

[0056] Comparative Example 1

[0057] The heat treatment process for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate described in this embodiment is the same as that in Example 1, except that no rare earth elements (La, Ce, Pr, and Yb) are added.

[0058] The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate described in this embodiment specifically includes the following steps:

[0059] (1) The TC4 alloy plate sample was pre-annealed at 300℃ for 2h to reduce the internal stress and improve the toughness. The sample was then subjected to asynchronous cold rolling. The speed ratio of the upper and lower rollers was 1.2. The total pressing amount of the sample was 50%, and the number of pressing times was 10, with the pressing amount each time not less than 5%.

[0060] (2) The alloy sample after asynchronous rolling in step (1) was subjected to a multi-stage solution treatment, with the first stage solution temperature at 850°C and a holding time of 2 hours; the second stage solution temperature at 900°C and a holding time of 2 hours; the third stage solution temperature at 950°C and a holding time of 2 hours; followed by water cooling quenching for 5 minutes; and finally artificial aging treatment at 400°C and a holding time of 4 hours. The yield strength of the alloy was measured to be 876.4 MPa, the tensile strength was 945.6 MPa, and the elongation was 10.4%.

[0061] The comparison shows that the strength of titanium alloys has decreased significantly. This may be because the solid solution of rare earth elements in the alloy can increase the resistance to dislocation movement, thereby increasing the strength of the material. Without the addition of rare earth elements, this solid solution strengthening effect may be weakened.

[0062] Comparative Example 2

[0063] The heat treatment process for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate described in this embodiment is the same as that in Example 1, except that only La is added as a rare earth element.

[0064] The yield strength of the alloy was measured to be 926.5 MPa, the tensile strength was 987.6 MPa, and the elongation was 11.6%.

[0065] By comparison, it can be seen that the yield strength and tensile strength of the alloy are significantly reduced compared to Example 1. The reason is that the single addition of La may lead to the formation of some unfavorable precipitation phases, causing stress concentration and reducing the plasticity of the alloy.

[0066] Comparative Example 3

[0067] The heat treatment process for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate described in this embodiment is the same as that in Example 1, except that only Ce is added as the rare earth element.

[0068] The yield strength of the alloy was measured to be 916.2 MPa, the tensile strength was 965.3 MPa, and the elongation was 13.9%.

[0069] By comparison, it can be seen that the Ce element has little effect on improving the strength of the alloy. The reason is that the solid solubility of Ce elements in the alloy is usually low, and they tend to form compounds or aggregate near the grain boundaries, thereby reducing the strength of the alloy.

[0070] Comparative Example 4

[0071] The heat treatment process for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate described in this embodiment is the same as that in Example 1, except that only Pr is added as a rare earth element.

[0072] The yield strength of the alloy was measured to be 913.4 MPa, the tensile strength was 1023.9 ​​MPa, and the elongation was 12.5%.

[0073] By comparison, it can be seen that the Pr element significantly reduces the yield strength of the alloy. The reason is that the addition of the Pr element alone may lead to the formation of some unfavorable precipitation phases.

[0074] Comparative Example 5

[0075] The heat treatment process for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate in this embodiment is the same as that in embodiment 1, except that only Yb is added as the rare earth element.

[0076] The yield strength of the alloy was measured to be 946.2 MPa, the tensile strength was 984.1 MPa, and the elongation was 11.2%.

[0077] By comparison, it can be seen that the effect of Yb element on improving the plastic toughness of the alloy is weak. The reason is that Yb element can prolong the aging response time of the alloy. As the aging time increases, the elongation of the material will decrease and the material will be more likely to break.

[0078] Comparative Example 6

[0079] The heat treatment process for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate in this embodiment is the same as that in embodiment 1, except that the asynchronous cold rolling process is changed to the ordinary cold rolling process.

[0080] The yield strength of the alloy was measured to be 947.2 MPa, the tensile strength was 992.4 MPa, and the elongation was 7.8%.

[0081] By comparison, it can be seen that conventional cold rolling has a lower elongation than asynchronous cold rolling. This is because during conventional cold rolling, the roll speed remains constant, which may result in higher rolling pressure. During cold rolling, the metal grains are elongated along the rolling direction, forming a fibrous structure, which results in directional properties of the metal. This deformation texture is not conducive to the uniform distribution of plastic deformation, significantly reducing the elongation of the material.

[0082] Table 4 Mechanical properties and corrosion test ratings of high-strength corrosion-resistant titanium alloys according to specific embodiments of the present invention

[0083]

[0084] In summary, the addition of a single rare earth element has little effect on the strength and corrosion resistance of the alloy, but the simultaneous addition of different rare earth elements can produce a synergistic effect in the titanium alloy, acting together on the microstructure and mechanical properties of the alloy; the combination of Pr and Yb can refine the grains and improve the strength and toughness of the alloy, while the combination of Ce and La can combine with oxygen to form stable oxides, reducing oxidation in the alloy and improving the corrosion resistance of the alloy. The joint addition of La, Ce and Yb rare earth elements can more effectively consume harmful solute atoms, thereby reducing grain boundary embrittlement and improving the strength of the alloy.

[0085] While conventional solution-aging treatment can improve the strength and corrosion resistance of alloys, the improvement is limited. In the present invention, a multi-stage solution-aging treatment can better activate rare earth elements to enhance the interfacial bonding strength between the precipitated phase and the titanium matrix. The combination of Ce, Pr, and Yb can more effectively enhance this interfacial bonding, thereby improving the strength and toughness of the alloy. Because the added rare earth elements typically have low solid solubility in the alloy, they tend to form compounds or aggregate near grain boundaries. The co-addition of multiple rare earth elements can more effectively consume harmful solute atoms, thereby reducing grain boundary embrittlement and significantly improving the strength of the alloy.

[0086] The high-strength, corrosion-resistant titanium alloy described in the present invention is obtained by adding these four rare earth elements simultaneously to form a high-density multi-level dislocation structure, which makes the solute atoms evenly distributed, improves the bonding strength between the precipitated phase and the matrix, greatly improves the strength and corrosion resistance of the plate, and thus obtains a titanium alloy that meets the performance requirements.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a high-strength, corrosion-resistant, fine-grained titanium alloy plate, characterized by: The strength and corrosion resistance of the material are improved by adding rare earth elements lanthanum, cerium, praseodymium and ytterbium to TC4 titanium alloy, combined with asynchronous cold rolling and solution treatment, which specifically includes the following steps: (1) Gas atomization treatment: The prepared rare earth raw materials and TC4 alloy raw materials are mixed by inert gas atomization treatment respectively; (2) The prepared powder is sequentially subjected to pressing and sintering, pre-annealing, asynchronous cold rolling, multi-stage solution treatment, and quenching; The multi-stage solution treatment has a first-stage solution temperature of 850°C and a holding time of 2 hours; a second-stage solution temperature of 900°C and a holding time of 2 hours; and a third-stage solution temperature of 950°C and a holding time of 2 hours. (3) The sample is then artificially aged at a temperature of 400-420°C for 4 hours, and then air-cooled to room temperature. The titanium alloy plate composition includes 5.5-6.5% Al, 3.7-4.2% V, 0.8-1.2% La, 0.03-0.05% Ce, 0.02-0.04% Pr, 0.01-0.02% Yb, and the remainder is Ti and some inevitable impurity elements.

2. The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate according to claim 1, characterized in that: The atomization pressure of the atomization method is 6.0MPa.

3. The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate according to claim 1, characterized in that: The pressing and sintering conditions are: sintering temperature is 1150-1300°C and the duration is 2h.

4. The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate according to claim 1, characterized in that: The parameters of the pre-annealing treatment are: 300~350℃ for 2h.

5. The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate according to claim 1, characterized in that: The conditions for asynchronous cold rolling treatment are: the total pressing amount of the sample is 50%, the number of pressing times is 10 times, and the pressing amount each time is not less than 5%.

6. The method for preparing the high-strength, corrosion-resistant, fine-grained titanium alloy plate according to claim 1, characterized in that: During the artificial aging treatment in step (3), the aging temperature is 400-420°C and the insulation time is 4 hours.

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