Tantalum-tungsten alloy fine-grain weak-texture structure regulation and control method

Abstract

The invention discloses a method for regulating and controlling a fine-grain weak texture structure of a tantalum-tungsten alloy. The method comprises the steps of electron beam smelting purification, heat treatment homogenization, pulse induction heating high-strain large-deformation, ultralow-temperature rolling and drawing-out and recrystallization vacuum gradient heat treatment. The tantalum-tungsten alloy material treated by adopting the scheme is good in structure uniformity, good in material strength and plasticity matching property and high in material yield.

Description

Technical Field

[0001] The invention relates to the technical field of tantalum-tungsten alloy forming, and in particular to a method for controlling the fine-grained weak-texture organization of tantalum-tungsten alloy. Background Art

[0002] Tantalum has a high density (16.67 g / cm 3 ), high corrosion resistance, tantalum alloys are widely used in chemical industry, electronics and other fields; tantalum's high melting point and high dynamic ductility make it an ideal material for rod jet (JPC) and explosively formed projectile (EFP) shaped shell (charge liner), and its penetration performance alone is more than 30% higher than copper, which can significantly improve the penetration ability and anti-interference ability at high blasting height. The shortcomings of tantalum tungsten components include: first, the grains have serious preferential orientation, forming a strong texture along the {111} and {100} planes, with a texture strength factor of more than 40; second, the grains are coarse and poorly uniform, with a grain size of 500 to 2000μm; this will not only reduce the material's forming performance and the qualified rate of component batch production, but will also cause the service performance of tantalum tungsten components to jump by more than 40mm, and the fluctuation value will reach 50%. Research shows that the strong texture of tantalum-tungsten alloy causes the penetrator to neck when it is deformed and stretched to an aspect ratio of less than 3, resulting in premature fracture and severe performance degradation; the mixed crystal structure has poor cohesion and deformation uniformity, and the penetrator head is divergent, with a power of only 40% to 50% of the ideal state; the poor texture symmetry of tantalum-tungsten alloy causes the penetrator to bend, greatly reducing its flight stability and speed, and the penetration depth value is reduced by about 50%.

[0003] At present, a lot of in-depth research has been conducted abroad on the relationship between liner materials, organization (grain size, morphology, distribution, grain orientation, etc.), geometric dimensional accuracy and damage effectiveness. The results show that under the same conditions of liner structural parameters and charge assembly, grain size and uniformity, texture (grain orientation) and other intrinsic organizational parameters have a significant impact on penetration capability, among which grain size and its distribution law are the key factors affecting the intrinsic quality of damage effectiveness. Therefore, it is necessary to develop a method for regulating the fine-grained weak texture organization of tantalum-tungsten alloy.

[0004] In addition, the existing conventional technologies related to organizational control methods (such as extrusion or multi-directional forging, reversing rolling) are used for fine-grained weak texture organizational control of tantalum-tungsten alloys, but they have the following disadvantages: First, the uniformity of grain size is poor, and there are uneven deformation shear bands and central undeformed areas in the weak deformation zone or the severe deformation zone, and a mixed crystal structure is formed after recrystallization; the material (tantalum-tungsten alloy rod) yield is less than 60%. Summary of the invention

[0005] At least in view of the problems mentioned in the background technology, the present invention aims to provide a method for controlling the fine-grained weak-texture structure of tantalum-tungsten alloy.

[0006] The present invention adopts the following technical solution.

[0007] A method for controlling fine-grained weak texture of tantalum-tungsten alloy, comprising: Step 1, electron beam melting and purification: alkali washing and acid washing are performed on the tantalum-tungsten alloy material; a power electron beam melting furnace is used to electron beam melt and purify the cleaned tantalum-tungsten alloy material to obtain a blank; Step 2, heat treatment and homogenization: heat treatment and homogenization of the blank obtained in step 1 in a vacuum furnace to obtain a heat-treated blank; Step 3, pulse induction heating with high strain and large deformation: the billet processed in step 2 is prepared into an ingot, and the ingot is subjected to pulse induction heating with high strain and large deformation on a screw press, and then immediately cooled in a cooling medium; Step 4, ultra-low temperature rolling and drawing: the ingot processed in step 3 is placed in a cooling medium for deep cryogenic treatment, and then rolled and drawn on a forging hammer to obtain a rod; Step 5, recrystallization vacuum gradient heat treatment: heat-treat the rod blank obtained in step 4 in a vacuum furnace for homogenization, and then cool it to below 100° C. and take it out of the furnace to obtain a tantalum-tungsten alloy material with a fine-grained weak texture.

[0008] Preferably, electron beam melting is performed twice in step 1: the first melting rate is (80-150) kg / h, and the billet drawing rate is (4-6) mm / min; the second melting rate is (50-100) kg / h, and the billet drawing rate is (2-4) mm / min; the vacuum degree of the melting chamber is ≥2×10 -3 Pa.

[0009] Preferably, the tantalum-tungsten alloy material in step 1 is a rod with a diameter of (50-100) mm and a length of not less than 400 mm.

[0010] Preferably, the process parameters for heat treatment homogenization in step 2 are: vacuum degree ≥ 3×10 -3 Pa, the heating rate is (5~15)℃ / min, and the insulation method is (600~800)℃×(15~30)min+1450℃×(1.5~2)h.

[0011] Preferably, the ingot length in step 3 is (100-200) mm; the hammer head rate during high strain and large deformation is 400-700 mm / s, the induction heating pulse frequency is 6-10 kHz, and the heating time is 20-30 s.

[0012] Preferably, the cryogenic treatment time in step 4 is (60-150) min, the length of the bar blank is Φ(30-60)×(200-800) mm, the mold system used for cryogenic treatment is cooled by liquid nitrogen atomization, and rolling and drawing are performed on a 7.5t forging hammer.

[0013] Preferably, the vacuum degree in step 5 is ≥ 3×10 -3 Pa, the heating rate is (5~15)℃ / min, and the insulation method is (600~850)℃×(15~20)min+(1050~1350)℃×(60~75)min.

[0014] Preferably, the tantalum-tungsten alloy material is TaW2.5, TaW5, or TaW10.

[0015] Preferably, an equal channel mold is used for pulse induction heating, high strain and large deformation. The equal channel mold includes an inverted T-shaped mold cavity, a pulse induction heating element is arranged around the vertical area of ​​the mold cavity, and a mold punch and a hammer are arranged above the vertical area of ​​the mold cavity.

[0016] Beneficial effects: The present invention solves the technical problems of high impurity content, uneven organization, and severe anisotropy of commercial tantalum-tungsten rods, and also has the advantages of high production efficiency, good process stability, and easy industrial production. The tantalum-tungsten alloy material treated by the scheme of the present invention has good organization uniformity, an average grain size of ≤10μm, an average grain size deviation of different parts of ≤1μm, a texture strength of grains with different orientations of 3 to 5, and a deviation of the core and the edge of ≤10%; the material strength and plasticity match well, the room temperature tensile strength of the obtained tantalum-tungsten alloy rod is 360 to 420MPa, and the elongation is 40 to 50%; the material yield rate reaches more than 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the high strain and large deformation process of pulse induction heating in the embodiment; Figure 2 The following is the organization and texture diagram of the tantalum-tungsten alloy rod obtained in the example. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. 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. Example 1

[0020] A method for controlling fine-grained weak texture of tantalum-tungsten alloy, comprising: Step 1, electron beam melting purification: use commercial Ta2.5W material with specifications of Φ80mm×400mm and average grain size of 1000μm; remove oil, scale and other substances on the surface of the material by alkali washing and acid washing; use an electron beam melting furnace with a power of 900kW to perform electron beam melting purification twice to obtain a blank, wherein the tantalum-tungsten alloy crystallizer has a side length of 80mm and the vacuum degree of the melting chamber is ≥2×10 -3 Pa, the first melting speed is 120kg / h, the billet drawing speed is 5mm / min, the second melting speed is 60kg / h, the billet drawing speed is 3mm / min; after the electron beam melting purification is completed, the modern material analysis method is used to obtain the impurity element content as shown in Table 1; Table 1 Impurity element content of tantalum-tungsten alloy blank Step 2, heat treatment homogenization: heat treatment homogenization of the blank obtained in step 1 in a vacuum furnace to obtain a heat-treated blank; wherein the vacuum degree is ≥ 3×10 -3 Pa, heating rate is 15℃ / min, insulation system is 800℃×25min+1450℃×1.5h, and the product is cooled to below 100℃ and then taken out of the furnace; Step 3, pulse induction heating high strain and large deformation: the billet processed in step 2 is prepared into two ingots with a length of 200 mm, and the ingots are subjected to high strain and large deformation on a screw press respectively, such as Figure 1 As shown; the entire mold is in a nitrogen atmosphere protection environment, the hammer head speed is 700mm / s, the induction heating pulse frequency is 9.5kHz, the heating time is 30s, and after completing the pulse induction heating high strain and large deformation, it is immediately cooled in the cooling medium to retain the core deformation energy storage; Step 4, ultra-low temperature rolling and drawing: the ingot processed in step 3 is placed in a cooling medium for cryogenic treatment for 120 minutes, the mold system used for cryogenic treatment is cooled by liquid nitrogen atomization, and then rolled and drawn on a 7.5t forging hammer to prepare two Φ40×800mm rods; Step 5: Recrystallization vacuum gradient heat treatment: The billet obtained in step 4 is heat treated in a vacuum furnace for homogenization, and the vacuum degree is ≥3×10 -3 Pa, the heating rate is 10℃ / min, the insulation system is 800℃×18min+1250℃×75min, and then the furnace is cooled to below 100℃ and taken out of the furnace to obtain tantalum-tungsten alloy material (rod) with fine grain and weak texture.

[0021] The yields of the two tantalum-tungsten alloy materials (rods) obtained in this embodiment are 87.5% and 85.1%, and the waste material at both ends is less than 70 mm. The tantalum-tungsten alloy material (rod) obtained in this embodiment is sampled, and the grain size and texture strength are tested by metallographic microscope and XRD. The results show that the average grain size of the obtained tantalum-tungsten alloy material is 6.8 μm (five random sampling positions, the core sampling is not less than two different positions), the texture strength of grains with different orientations is 3.99 (such as Figure 2 As shown in the figure (compared with the texture strength of 10-15 of different oriented grains of the same specification of tantalum-tungsten alloy obtained by conventional extrusion process, it has been significantly optimized). The mechanical properties test results are: the room temperature tensile strength of the obtained tantalum-tungsten alloy material is (365-374) MPa, and the elongation after fracture is (45.5-47)%. Example 2

[0022] A method for controlling fine-grained weak texture of tantalum-tungsten alloy, comprising: Step 1, electron beam melting purification: commercial Ta5W material with specifications of Φ80mm×200mm and average grain size of 800μm is used. Surface oil, scale and other substances are removed by alkali washing and acid washing. An electron beam melting furnace with a power of 900kW is used for electron beam melting purification twice. The side length of the tantalum-tungsten alloy crystallizer is 80mm, and the vacuum degree of the melting chamber is ≥2×10 -3 Pa, the first melting speed is 120kg / h, the billet drawing speed is 5mm / min; the second melting speed is 60kg / h, the billet drawing speed is 3mm / min; Step 2: Heat treatment homogenization: The blank obtained in step 1 is heat treated homogenization in a vacuum furnace with a vacuum degree of ≥ 3×10 -3 Pa, heating rate is 15℃ / min, holding system is 800℃×35min+1450℃×2h, cooling to below 100℃ and taking out of the furnace to obtain the heat-treated blank; Step 3, pulse induction heating with high strain and large deformation: the billet processed in step 2 is prepared into a 200 mm long ingot, and pulse induction heating with high strain and large deformation is performed on a screw press; wherein the entire mold is in a nitrogen atmosphere protection environment, the hammer head speed is 700 mm / s, the induction heating pulse frequency is 10 kHz, and the heating time is 25 s. After the pulse induction heating with high strain and large deformation is completed, it is immediately cooled in a cooling medium to retain the deformation energy storage in the core; Step 4, ultra-low temperature rolling and drawing: the ingot processed in step 3 is placed in a cooling medium for deep cryogenic treatment for 120 minutes, the mold system is cooled by liquid nitrogen atomization, and rolling and drawing is performed on a 7.5t forging hammer to prepare a Φ30×142.2mm bar blank; Step 5: Recrystallization vacuum gradient heat treatment: The billet obtained in step 4 is heat treated in a vacuum furnace for homogenization, and the vacuum degree is ≥3×10 -3 Pa, the heating rate is 15℃ / min, the insulation system is 850℃×20min+1350℃×70min, and the furnace is cooled to below 100℃ and then taken out of the furnace to obtain tantalum-tungsten alloy material (rod) with fine grain and weak texture.

[0023] The yield of the tantalum-tungsten alloy material (rod) obtained in this embodiment is 91.2%, and the waste material at both ends is less than 10 mm; the tantalum-tungsten alloy material (rod) obtained in this embodiment is sampled, and the grain size and texture strength are tested by metallographic microscope and XRD. The results show that the average grain size of the obtained tantalum-tungsten alloy material is 7.4 μm (three random sampling locations, the core sampling is two different locations), and the texture strength of grains with different orientations is 4.65. The mechanical properties test results are: the room temperature tensile strength of the obtained tantalum-tungsten alloy material is (396-415) MPa, and the elongation after fracture is (40-41.5)%. Example 3

[0024] A method for controlling fine-grained weak texture of tantalum-tungsten alloy, comprising: Step 1, electron beam melting purification: commercial Ta2.5W material with specifications of Φ50mm×200mm and average grain size of 800μm is used, and surface oil, oxide scale and other substances are removed by alkali washing and acid washing; an electron beam melting furnace with a power of 900kW is used to perform electron beam melting purification twice to obtain a blank; wherein, the side length of the tantalum-tungsten alloy crystallizer is 80mm, and the vacuum degree of the melting chamber is ≥2×10 -3 Pa, the first melting speed is 120kg / h, the billet drawing speed is 5mm / min; the second melting speed is 60kg / h, the billet drawing speed is 3mm / min; Step 2, heat treatment homogenization: heat treatment homogenization of the blank obtained in step 1 in a vacuum furnace to obtain a heat-treated blank; wherein the vacuum degree is ≥ 3×10 -3 Pa, heating rate is 15℃ / min, insulation system is 800℃×25min+1450℃×1.5h, and the product is cooled to below 100℃ and then taken out of the furnace; Step 3, pulse induction heating with high strain and large deformation: the billet processed in step 2 is prepared into a 100 mm long ingot, and pulse induction heating with high strain and large deformation is performed on a screw press; wherein the entire mold is in a nitrogen atmosphere protection environment, the hammer head speed is 500 mm / s, the induction heating pulse frequency is 7 kHz, the heating time is 20 s, and after the pulse induction heating with high strain and large deformation is completed, it is immediately cooled in a cooling medium; Step 4, ultra-low temperature rolling and drawing: the ingot processed in step 3 is placed in a cooling medium for deep cryogenic treatment for 80 minutes, the mold system used for deep cryogenic treatment is cooled by liquid nitrogen atomization, and rolling and drawing are performed on a 7.5t forging hammer to prepare a Φ40×312.5mm bar. Step 5: Recrystallization vacuum gradient heat treatment: The billet obtained in step 4 is heat treated in a vacuum furnace for homogenization, and the vacuum degree is ≥3×10 -3 Pa, the heating rate is 15℃ / min, the insulation system is 750℃×20min+1150℃×60min, and the furnace is cooled to below 100℃ and then taken out of the furnace to obtain tantalum-tungsten alloy material (rod) with fine grain and weak texture.

[0025] The yield of the tantalum-tungsten alloy material (rod) obtained in this embodiment is 90.1%, and the waste material at both ends is less than 20 mm; the tantalum-tungsten alloy material (rod) obtained in this embodiment is sampled, and the grain size and texture strength are tested by metallographic microscope and XRD. The results show that the average grain size of the obtained tantalum-tungsten alloy material is 8 μm (three random sampling locations, the core sampling is two different locations), and the texture strength of grains with different orientations is 2.78. The mechanical properties test results are: the room temperature tensile strength of the obtained tantalum-tungsten alloy material is (360-370) MPa, and the elongation after fracture is (46-48)%.

[0026] The tantalum-tungsten alloy material treated by the embodiment scheme has good uniformity of structure, an average grain size of ≤10μm, an average grain size deviation of different parts of ≤1μm, a texture strength of grains with different orientations of 3-5, and a deviation of the core and the edge of ≤10%; good matching of material strength and plasticity, the obtained tantalum-tungsten alloy rod has a room temperature tensile strength of 360-420MPa, and an elongation of 40-50%; and the material yield rate reaches more than 80%.

Claims

1. A method for controlling fine grain weak texture of tantalum-tungsten alloy, characterized in that the steps include: Step 1, electron beam melting and purification: alkali washing and acid washing are performed on the tantalum-tungsten alloy material; a power electron beam melting furnace is used to electron beam melt and purify the cleaned tantalum-tungsten alloy material to obtain a blank; Step 2, heat treatment and homogenization: heat treatment and homogenization of the blank obtained in step 1 in a vacuum furnace to obtain a heat-treated blank; Step 3, pulse induction heating with high strain and large deformation: the billet processed in step 2 is prepared into an ingot, and the ingot is subjected to pulse induction heating with high strain and large deformation on a screw press, and then immediately cooled in a cooling medium; Step 4, ultra-low temperature rolling and drawing: the ingot processed in step 3 is placed in a cooling medium for deep cryogenic treatment, and then rolled and drawn on a forging hammer to obtain a rod; Step 5, recrystallization vacuum gradient heat treatment: heat-treat the rod blank obtained in step 4 in a vacuum furnace for homogenization, and then cool it to below 100° C. and take it out of the furnace to obtain a tantalum-tungsten alloy material with a fine-grained weak texture.

2. The method for controlling the fine-grained weak texture of tantalum-tungsten alloy according to claim 1, characterized in that: In step 1, electron beam melting is performed twice: the first melting speed is (80-150) kg / h, and the billet drawing speed is (4-6) mm / min; the second melting speed is (50-100) kg / h, and the billet drawing speed is (2-4) mm / min; the vacuum degree of the melting chamber is ≥2×10 -3 Pa.

3. The method for controlling the fine-grained weak texture of tantalum-tungsten alloy according to claim 1, characterized in that: The tantalum-tungsten alloy material in step 1 is a rod with a diameter of (50-100) mm and a length of not less than 400 mm.

4. The method for controlling the fine-grained weak texture of tantalum-tungsten alloy according to claim 1, characterized in that: The process parameters for heat treatment homogenization in step 2 are: vacuum degree ≥ 3×10 -3 Pa, the heating rate is (5-15)℃ / min, and the insulation method is (600-800)℃×(15-30)min+1450℃×(1.5-2)h.

5. The method for controlling fine grain weak texture of tantalum-tungsten alloy according to any one of claims 1 to 4, characterized in that: The ingot length in step 3 is (100-200) mm; the hammer head speed during high strain and large deformation is 400-700 mm / s, the induction heating pulse frequency is 6-10 kHz, and the heating time is 20-30 s.

6. The method for controlling the fine-grained weak texture of tantalum-tungsten alloy according to claim 5, characterized in that: In step 4, the cryogenic treatment time is (60-150) min, the length of the bar blank is Φ (30-60) × (200-800) mm, the mold system used for cryogenic treatment is cooled by liquid nitrogen atomization, and rolling and drawing are performed on a 7.5t forging hammer.

7. The method for controlling the fine grain weak texture of tantalum-tungsten alloy according to claim 6, characterized in that: In step 5, the vacuum degree is ≥ 3×10 -3 Pa, the heating rate is (5-15)℃ / min, and the insulation method is (600-850)℃×(15-20)min+(1050-1350)℃×(60-75)min.

8. The method for controlling the fine-grained weak texture of tantalum-tungsten alloy according to claim 7, characterized in that: Tantalum tungsten alloy materials include TaW2.5, TaW5 and TaW10.

9. The method for controlling the fine-grained weak texture of tantalum-tungsten alloy according to claim 8, characterized in that: An equal channel die is used for pulse induction heating with high strain and large deformation. The equal channel die includes an inverted T-shaped die cavity. A pulse induction heating element is arranged outside the vertical area of ​​the die cavity. A die punch and a hammer are arranged above the vertical area of ​​the die cavity.

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