Thermal mechanical treatment method of TC4B titanium alloy for armor

Abstract

The invention relates to a thermal mechanical treatment method of a TC4B titanium alloy for armor, which comprises the following steps: obtaining a TC4B titanium alloy slab ingot through single smelting in an EB furnace, slitting the obtained slab ingot, then carrying out scaling treatment, and coating a high-temperature anti-oxidation coating; the titanium alloy slab ingot coated with the high-temperature anti-oxidation coating is subjected to one-heating-number hot rolling treatment in the length direction, and a primary titanium alloy slab is obtained; after the primary titanium alloy plate blank is subjected to scaling and coping treatment, one-heating-number or two-heating-number alternate reversing rolling is carried out, and a secondary titanium alloy plate blank is obtained; after the secondary titanium alloy plate blank is subjected to surface treatment and coping, finished product heating number hot rolling is conducted, and a final titanium alloy plate blank is obtained; the final titanium alloy plate blank is subjected to heat treatment, and a finished titanium alloy plate is obtained; according to the method, the rolling deformation technology and heat treatment are combined, the microstructure of the alloy is effectively regulated and controlled, the TC4B titanium alloy plate with the tri-state structure is obtained, and the prepared TC4B titanium alloy plate has the excellent mechanical property.

Description

Technical Field

[0001] The invention relates to the field of titanium and titanium alloy processing, and is a method for thermomechanical treatment of TC4B titanium alloy for armor. Background Art

[0002] Titanium alloy not only has excellent mechanical properties, but also has a lighter weight as an armor material than traditional armor steel materials. It is the preferred material for lightweight and strong protection of the new generation of armor equipment. For the low-cost development of metal materials for armor, progress has been made in the process technologies such as adding return materials, single melting in electron beam cooling furnace, and direct rolling of flat ingots. However, the use of recycled materials and short-process technology have not yet formed a complete engineering application technology.

[0003] Judging from the grades of armor titanium alloys developed at home and abroad, a variety of high-strength armor titanium alloys have been developed based on TC4 titanium alloy, including TC4A, TC4B, Ti555, TC52, etc. In recent years, studies have shown that when the microstructure of titanium alloy presents a three-state structure of 10-15% primary α + 40-60% lamellar α + partially transformed β matrix, it exhibits excellent mechanical properties and can meet the use requirements of armored vehicles, turrets and other components. Harbin Institute of Technology proposed a heat treatment process for obtaining a three-state structure in a two-state structure after pre-treatment. Sun Zhichao et al. proposed a method for obtaining a three-state structure by heat treatment at a near-β temperature in CN102758161A. The methods proposed in the two patents require that the material is a molding material or the structure is a two-state structure. The high-temperature heat treatment for multiple times and for a long time increases the production energy consumption, the process flow is long, and the high-temperature treatment process for multiple times is very likely to cause grain coarsening. Jilin University proposed a method for preparing a three-state structure by combining pulse current treatment with conventional heat treatment in CN117026122A. This method is only applicable to molded workpieces, and the workpiece surface is clean and free of impurities and has good conductivity. It is still limited to the industrial production of conventional workshops. In addition, some researchers use near-β forging technology to obtain the three-state structure. The temperature range during the forging process is not easy to control, the organizational morphology is unstable, and the single-pass deformation requirement is high, which is easy to cause surface cracking. Based on the above research, it is found that the way to obtain the three-state structure mainly includes high-temperature deformation and 3 to 4 or more heat treatments, that is, from the perspective of the entire process of smelting, forging, rolling, and heat treatment, the process is complex and the production cycle is long. The flat ingots made by the EB furnace can be directly rolled without forging, with low cost and short production cycle, but the surface of the slab is prone to cracking during the first-fire rolling process, and the yield is low. Therefore, it has become an urgent problem to prepare the three-state structure of titanium alloy with low cost, high yield and stable performance in a short process. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes a thermomechanical treatment method for TC4B titanium alloy for armor, which has low cost, short processing cycle, high yield rate and can obtain tri-state titanium alloy plate with excellent comprehensive performance.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a thermomechanical treatment method of TC4B titanium alloy for armor, comprising the following steps:

[0007] S1. Obtain TC4B titanium alloy flat ingots by single smelting in an EB furnace, cut the obtained flat ingots into pieces, perform peeling treatment, and apply high-temperature anti-oxidation coating;

[0008] S2, performing a hot rolling treatment on the titanium alloy flat ingot coated with the high-temperature anti-oxidation coating along the length direction to obtain a primary titanium alloy slab;

[0009] S3, after peeling and grinding the primary titanium alloy slab, performing one or two rounds of alternating rolling to obtain a secondary titanium alloy slab;

[0010] S4, performing surface treatment and grinding on the secondary titanium alloy slab and then hot rolling it to obtain a final titanium alloy slab;

[0011] S5. Heat-treating the final titanium alloy slab to obtain a finished titanium alloy plate.

[0012] Preferably, in S2, the initial temperature of hot rolling is 50-80°C higher than the phase transformation point.

[0013] Preferably, in S3, the initial temperature of each hot rolling is 40-60°C below the phase transformation point of the titanium alloy.

[0014] Preferably, in S3, when the thickness of the finished titanium alloy plate in the design target is ≥12 mm, the primary titanium alloy slab is hot rolled for one round; when the thickness of the finished titanium alloy plate in the design target is <12 mm, the primary titanium alloy slab is rolled for two rounds.

[0015] Preferably, in S4, the rolling temperature of the finished product is 10 to 25° C. below the alloy phase transformation point.

[0016] Preferably, in S5, the heat treatment method is to keep the temperature at 780-850°C for 3-5h and then air cool.

[0017] Preferably, in S2, during the hot rolling process, the hot rolling deformation amount in the main deformation rolling process is 13-16%, and the total deformation amount is 70-80%.

[0018] Preferably, in S3, the specific method of alternating hot rolling is: the hot rolling direction of each hot rolling is perpendicular to the hot rolling direction of the previous hot rolling.

[0019] Preferably, in S3, during each hot rolling process, the deformation amount of a single hot rolling pass is 7-12%, and the total deformation amount is 45-55%.

[0020] Preferably, in S4, during the hot rolling process of the finished product, the deformation amount of the main deformation rolling process is 10% to 15%, and the total hot rolling deformation amount is 50% to 60%.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention performs double reversing forging-free direct rolling on the flat ingots melted in the EB furnace, which can not only shorten the production cycle and reduce the processing cost, but also make the prepared slabs fine in structure and uniform in uniformity, avoid the problem of slab surface cracking during the rolling process, and ensure a high yield rate.

[0023] (2) The present invention combines the rolling deformation process with the heat treatment, and utilizes the deformation hot rolling and the final heat treatment of the finished product to effectively control the alloy microstructure, thereby obtaining a TC4B titanium alloy plate with a three-state structure, so that the obtained TC4B titanium alloy plate has excellent mechanical properties, which is beneficial to improving the armor protection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a process flow chart of the present invention;

[0025] Figure 2 This is a metallographic photograph of the original cast structure of Example 1 of the present invention;

[0026] Figure 3 The three-state structure morphology obtained after heat treatment of the sample in Example 1 of the present invention;

[0027] Figure 4 The three-state structure morphology obtained after heat treatment of the sample in Example 2 of the present invention;

[0028] Figure 5 The three-state structure morphology obtained after heat treatment of the sample in Example 3 of the present invention;

[0029] Figure 6 This is the organizational morphology of the sample obtained in Comparative Example 1; DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] refer to Figure 1 This embodiment provides a thermomechanical treatment method for TC4B titanium alloy for armor, comprising the following steps:

[0033] S1. According to the design target of TC4B titanium alloy, 3568 kg of raw materials are weighed, and a single smelting is performed in an EB furnace to obtain a TC4B titanium alloy ingot. The obtained ingot is cut into target sizes of 347 mm × 1455 mm × 1567 mm, and the surface of the cut ingot is cleaned and coated with a high-temperature anti-oxidation coating;

[0034] S2, subjecting the titanium alloy slab to a first round of hot rolling treatment in the β phase region at 78°C above the phase transformation point, i.e., the initial temperature of the first round of hot rolling is 1050°C, the hot rolling direction is the length direction of the slab, the hot rolling deformation amount of the main deformation rolling process is 14%, and the total deformation amount is 78.5%. After the first round of hot rolling is completed, the titanium alloy slab is straightened while the residual temperature is maintained to obtain a primary titanium alloy slab;

[0035] S3, after cutting the primary titanium alloy slab, the slab is fully peeled and ground, and the second hot rolling is carried out to obtain the secondary titanium alloy slab. The initial temperature of the second hot rolling is 40°C below the phase transition point of the titanium alloy, and the direction of the second hot rolling is perpendicular to the direction of the first hot rolling. During the second hot rolling, the single hot rolling deformation is in the range of 7-12%, and the total deformation is 45.5%;

[0036] S4, performing hot rolling of the secondary titanium alloy slab in the finished product heat, wherein the initial rolling temperature is 12°C below the phase transition point temperature of the titanium alloy, the deformation amount of the main deformation rolling process is 11%, and the total deformation amount is 50%, and then performing surface treatment and grinding on the slab obtained after the hot rolling of the finished product heat to obtain the final titanium alloy slab;

[0037] S5. The final titanium alloy slab is heat treated at a temperature of 780° C. for 5 h and then air-cooled to obtain a finished titanium alloy plate with a thickness of 20 mm.

[0038] Example 2

[0039] This embodiment provides a thermomechanical treatment method for TC4B titanium alloy for armor, comprising the following steps:

[0040] S1. According to the design target of TC4B titanium alloy, 3855 kg of raw materials are weighed, and a single smelting is performed in an EB furnace to obtain a TC4B titanium alloy ingot. The obtained ingot is cut into target sizes of 335 mm × 1553 mm × 1642 mm, and the surface of the cut ingot is cleaned and coated with a high-temperature anti-oxidation coating;

[0041] S2, performing a first hot rolling treatment on the titanium alloy slab coated with a high-temperature anti-oxidation coating in the β phase region 60°C above the phase transition point, that is, the initial temperature of the first hot rolling is 1032°C, the hot rolling direction is the length direction of the slab, the total deformation is 71%, and after the first hot rolling is completed, the titanium alloy slab is straightened while the residual temperature is maintained to obtain a primary titanium alloy slab;

[0042] S3, after cutting the primary titanium alloy slab, the whole skin is peeled and ground, reheated, and the second round of reversing hot rolling is carried out, that is, the rolling direction of the second round is perpendicular to the rolling direction of the first round, the initial temperature of hot rolling is 50°C below the phase transition point, the deformation of a single hot rolling is controlled within the range of 7% to 12%, and the total deformation is 50%; after the second round, the third round of reversing rolling is carried out, that is, the rolling direction of the third round is perpendicular to the rolling direction of the second round, the initial temperature of hot rolling is consistent with the second round of hot rolling, the deformation of a single hot rolling is controlled within the range of 7% to 12%, and the total deformation is 41%, so as to obtain a secondary titanium alloy slab;

[0043] S4, firstly perform hot rolling of the secondary titanium alloy slab in the finished product fire; the initial rolling temperature is 22°C below the phase transition point temperature of the titanium alloy, the deformation amount of the main deformation rolling process is 12%, and the deformation amount is 60%, and then the slab obtained after the hot rolling of the finished product fire is surface treated and ground to obtain the final titanium alloy slab;

[0044] S5. The final titanium alloy slab is heat treated at a temperature of 850° C. for 3 h and then air-cooled to obtain a finished titanium alloy plate with a thickness of 10 mm.

[0045] Example 3

[0046] This embodiment provides a thermomechanical treatment method for TC4B titanium alloy for armor, comprising the following steps:

[0047] S1. According to the design target of TC4B titanium alloy, 3155 kg of raw materials are weighed, and a single smelting is performed in an EB furnace to obtain a TC4B titanium alloy ingot. The obtained ingot is cut into target sizes of 347 mm × 1455 mm × 1386 mm, and the surface of the cut ingot is cleaned and coated with a high-temperature anti-oxidation coating;

[0048] S2, performing the first hot rolling treatment on the titanium alloy slab coated with the high-temperature anti-oxidation coating in the β phase region 48°C above the phase transition point, that is, the initial temperature of the first hot rolling is 1020°C, the hot rolling direction is the length direction of the slab, and during the first hot rolling, the main deformation hot rolling deformation is 15%, and the total deformation is 75%. After the first hot rolling is completed, the titanium alloy slab is straightened while the residual temperature is maintained to obtain a primary titanium alloy slab;

[0049] S3, after cutting the primary titanium alloy slab, the whole skin is peeled and ground, and the second round of reversing hot rolling is carried out, the initial temperature is 60°C below the phase transformation point of the titanium alloy, the rolling direction of the second round is perpendicular to the rolling direction of the first round, and during the second round of hot rolling, the single-pass hot rolling deformation is in the range of 7-12%, and the total deformation is 54.5%, and the secondary titanium alloy slab is obtained at this time;

[0050] S4, firstly perform hot rolling of the secondary titanium alloy slab in the finished product fire, the initial rolling temperature is 15°C below the phase transition point temperature of the titanium alloy, the deformation of the main deformation rolling process is 14%, and the total deformation is 55%, and finally the slab obtained after the hot rolling of the finished product fire is subjected to surface treatment and grinding to obtain the final titanium alloy slab;

[0051] S5. The final titanium alloy slab is heat treated at a temperature of 810° C. for 4 hours and then air-cooled to obtain a finished titanium alloy plate with a thickness of 17 mm.

[0052] Comparative Example 1

[0053] This comparative example is a conventional thermomechanical treatment method for TC4B titanium alloy for armor, comprising the following steps:

[0054] S1. According to the design target of TC4B titanium alloy, 2694 kg of raw materials were weighed and smelted in a single process in an EB furnace to obtain an ingot with a size of φ650 mm × 1850 mm;

[0055] S2, coating the ingot with a high-temperature anti-oxidation coating, heating it to a β phase region above the phase transition point, and then performing a first fire forging treatment, with the initial forging temperature being 120° C. above the phase transition point; after cooling, heating is performed, and then a second fire forging is performed, with the initial forging temperature being 10° C. above the phase transition point, and finally a titanium alloy slab with a size of 260 mm×1260 mm×1855 mm is obtained;

[0056] S3. Hot rolling the forged titanium alloy slab. The initial temperature of the first hot rolling is 40°C below the phase transition point of the titanium alloy, the rolling direction is the length direction of the slab, and the total deformation is 71.5%; after the first hot rolling, the material is straightened at residual temperature and cut to a width of 2000mm, followed by the second hot rolling, the initial temperature of the hot rolling is 50°C below the phase transition point, the rolling direction is the direction of 90° rotation of the axial direction of the first hot rolling, and the total deformation is 51%; after the second hot rolling, the material is straightened at residual temperature, and the third hot rolling is carried out, the initial temperature of the hot rolling is 90° below the phase transition point of the titanium alloy, the rolling direction remains unchanged, and the total deformation is 44.4%, to obtain the ultimate titanium alloy slab;

[0057] S4. The final titanium alloy slab is first subjected to the first heat treatment, the heat treatment system is to keep it at 965℃ for 1h and then water cool it; after cooling, it is subjected to the second heat treatment, the heat treatment system is to keep it at 800℃ for 3h and then air cool it; finally, it is subjected to the third heat treatment, the heat treatment system is to keep it at 600℃ for 4h and then air cool it.

[0058] In order to better illustrate the beneficial effects of the present invention, the microstructures of the flat ingots prepared by the EB furnace in Example 1 and the plates prepared in Examples 1 to 3 and Comparative Example 1 were observed. Figures 2 to 6 As shown; and referring to GB / T228.1-2021, the mechanical properties of the plates prepared in Examples 1 to 3 and Comparative Example 1 were tested, and the results are shown in Table 1:

[0059] Table 1 Mechanical properties test results

[0060]

[0061] It can be seen from Table 1 that the impact absorption energy of the plate prepared by the present invention can reach more than 40 joules, which is higher than the 30 joules required for armor materials. At the same time, the tensile strength can reach more than 1010 MPa. The comprehensive performance is significantly improved compared with the titanium alloy plate prepared by conventional processes.

[0062] from Figure 2 It can be seen that the grain size of the flat ingot prepared by the EB furnace is much larger than 100 μm; after being processed by the technical means used in the present invention, the following grain sizes of different regions are obtained: Figures 3 to 5 The three-state structure of primary α + 40-60% lamellar α + partially transformed β matrix is ​​shown: the primary α phase accounts for about 10-15% and is relatively small in size, about 10μm; the small lamellar α phase accounts for a large proportion, about 40-60%, and the size is generally short flakes of 2μm wide and 20μm long; in addition, there are some partially transformed β matrix. Figures 3 to 5 It can also be seen that the microstructures of different regions of the titanium alloy are similar, indicating that the three-state structure of the titanium alloy prepared by this method is evenly distributed. Figure 6The titanium alloy sheet prepared by the conventional method shown is mainly composed of transformed β matrix, equiaxed α phase and elongated α phase. Among them, the elongated α phase occupies most of the area, its size is generally large, greater than 20μm in the length direction, and some are connected into sheets.

[0063] The specific embodiments of the present invention enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0064] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A thermomechanical treatment method for TC4B titanium alloy for armor, characterized in that: The following steps are involved: S1. Obtain TC4B titanium alloy flat ingots by single smelting in an EB furnace, cut the obtained flat ingots into pieces, perform peeling treatment, and apply high-temperature anti-oxidation coating; S2, performing a hot rolling treatment on the titanium alloy flat ingot coated with the high-temperature anti-oxidation coating along the length direction to obtain a primary titanium alloy slab; S3, after peeling and grinding the primary titanium alloy slab, performing one or two rounds of alternating rolling to obtain a secondary titanium alloy slab; S4, performing surface treatment and grinding on the secondary titanium alloy slab and then hot rolling it to obtain a final titanium alloy slab; S5. Heat-treating the final titanium alloy slab to obtain a finished titanium alloy plate.

2. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S2, the initial temperature of hot rolling is 50-80°C higher than the phase transformation point.

3. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S3, the initial temperature of each hot rolling is 40-60°C below the phase transformation point of the titanium alloy.

4. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S3, when the thickness of the finished titanium alloy plate in the design target is ≥12mm, the primary titanium alloy slab is hot rolled for one round; when the thickness of the finished titanium alloy plate in the design target is <12mm, the primary titanium alloy slab is rolled for two rounds.

5. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S4, the rolling temperature of the finished product is 10 to 25° C. below the alloy phase transformation point.

6. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S5, the heat treatment method is to keep the temperature at 780-850°C for 3-5h and then air cool.

7. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S2, during the hot rolling process, the hot rolling deformation amount of the main deformation rolling process is 13-16%, and the total deformation amount is 70-80%.

8. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S3, the specific method of alternating hot rolling is: the hot rolling direction of each hot rolling is perpendicular to the hot rolling direction of the previous hot rolling.

9. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S3, during each hot rolling process, the deformation of a single hot rolling pass is 7-12%, and the total deformation is 45-55%.

10. The thermomechanical treatment method of TC4B titanium alloy for armor according to claim 1, characterized in that: In S4, during the hot rolling of the finished product, the deformation of the main deformation rolling process is 10% to 15%, and the total hot rolling deformation is 50% to 60%.

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