Method for improving self-sharpening property of tungsten alloy by prefabricating microcracks

Abstract

The invention discloses a method for improving self-sharpening of tungsten alloy by prefabricating microcracks, and belongs to the technical field of tungsten alloy machining. The method for improving the self-sharpening property of the tungsten alloy by prefabricating the microcracks comprises the following steps that a formed tungsten alloy blank is subjected to prefabricating microcrack treatment, and the tungsten alloy is obtained; the number of the tungsten particles with the prefabricated microcracks in the tungsten alloy accounts for 7-17% of the total number of the tungsten particles. According to the method, the content of the number of the tungsten particles containing the prefabricated microcracks is regulated and controlled through rotary forging, and the static / dynamic mechanical property balance of the alloy is optimized. The microcracks are used as shear failure starting points, the adiabatic shear sensitivity can be remarkably improved, the dynamic impact strength of the material reaches 1835-2072 MPa (2000 / s strain rate), meanwhile, the quasi-static tensile strength is kept to be larger than or equal to 1270 MPa, and the ductility is kept to be larger than or equal to 7%.

Description

Technical Field

[0001] The present invention relates to the technical field of tungsten alloy processing, and particularly relates to a method for improving the self-sharpening property of tungsten alloy by prefabricating microcracks. Background Art

[0002] High-density tungsten alloys (WHAS) and depleted uranium (DU) alloys are the main materials for preparing armor-piercing projectiles. Due to its good adiabatic shear sensitivity, the depleted uranium armor-piercing projectile has an obvious "self-sharpening" behavior during the armor-piercing process and has excellent penetration ability. However, the depleted uranium alloy will cause irreversible pollution to the environment. While the adiabatic shear sensitivity of the high-density tungsten alloy is poor, and it is easy to form a mushroom head during penetration, resulting in limited self-sharpening property and penetration depth effect.

[0003] In recent years, domestic and foreign researchers have done a lot of research to improve the adiabatic shear sensitivity of tungsten alloys and the penetration performance of tungsten alloy armor-piercing projectiles. Some scholars have improved the mechanical properties of the alloy by changing the composition of the tungsten alloy to improve its penetration performance as an armor-piercing projectile. For example, W-Ni-Fe series, W-Ni-Co series, W-Cu-Zn series, etc. However, these alloys all have the problems of insufficient adiabatic shear sensitivity and insignificant self-sharpening effect. In addition, the shear failure performance of tungsten alloy can be improved by refining the grain size, but it is difficult to prepare large-size specimens due to equipment limitations, and it is relatively difficult in engineering applications. On the other hand, strain hardening can improve the strength of tungsten alloy and improve the "self-sharpening" behavior of the tungsten alloy projectile core, but there is still a problem that it is easy to generate a "mushroom head" during armor-piercing, resulting in a decrease in armor-piercing performance (penetration performance). Summary of the Invention

[0004] The purpose of the present invention is to provide a method for improving the self-sharpening property of tungsten alloy by prefabricating microcracks to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above purpose, the present invention provides the following scheme:

[0006] One of the technical solutions of the present invention: A method for improving the self-sharpening property of tungsten alloy by prefabricating microcracks, comprising the following steps:

[0007] Perform prefabricated microcrack treatment on the formed tungsten alloy blank to obtain tungsten alloy (high-density tungsten alloy with prefabricated microcracks);

[0008] The number of tungsten particles containing prefabricated microcracks in the tungsten alloy accounts for 7-17% of the total number of tungsten particles.

[0009] Further, the preparation method of the formed tungsten alloy blank comprises the following steps:

[0010] Mix the W powder, Ni powder and Fe powder evenly and then press them into a blank;

[0011] Perform pre-sintering and sintering on the blank, and then perform dehydrogenation heat treatment to obtain a formed tungsten alloy blank.

[0012] Further, the blank, in terms of mass percentage, includes the following components: 90-93% of W powder, 5-7% of Ni powder and 2-3% of Fe powder.

[0013] Further, the pressing is cold isostatic pressing, the pressing pressure is 150-180 MPa, and the pressing time is 90-150 s;

[0014] The temperature of the pre-sintering is 1100-1200 °C, the heat preservation time is 0.5-1 h, and the atmosphere is ammonia decomposition gas;

[0015] The temperature of the sintering is 1420-1470 °C, the heat preservation time is 1-1.5 h, and the atmosphere is ammonia decomposition gas.

[0016] Further, the heating rate of the dehydrogenation heat treatment is 5-10 °C / min, the temperature is 1100-1200 °C, and the heat preservation time is 1-3 h.

[0017] Further, the method adopted for the prefabricated microcrack treatment includes rotary forging.

[0018] Further, the rotary forging includes: first heating to 550-600 °C at a heating rate of 5-15 °C / min, heat preserving for 7-12 min, and then performing rotary forging at a rotary forging speed of 50-300 r / min.

[0019] The quasi-static mechanical properties of the high-density tungsten alloy with prefabricated microcracks prepared by the method of the present invention are equivalent to those of the tungsten alloy obtained by conventional forging; and when undergoing high-speed deformation, the prefabricated microcracks in the high-density tungsten alloy prepared by the present invention can accelerate the crack propagation in the deformation shear band, causing the alloy to undergo shear failure at a lower strain, improving its adiabatic shear failure performance, and further enhancing the self-sharpening property of the high-density tungsten alloy armor-piercing projectile.

[0020] The present invention prepares a high-density tungsten alloy that is relatively easy to produce adiabatic shear failure and maintains good strength and toughness by adjusting the process parameters of rotary forging to control the content of prefabricated microcracks in the tungsten alloy (the content of tungsten particles containing prefabricated microcracks), slows down the "mushroom head" effect of tungsten alloy armor-piercing, and further enhances the self-sharpening property of the high-density tungsten alloy.

[0021] Tungsten alloy armor-piercing projectiles not only require good adiabatic shear properties but also maintain good quasi-static strength and toughness. To obtain an alloy with balanced static / dynamic mechanical properties, in the present invention, by introducing different contents of microcracks, it is found that when the content of microcracks is excessive, the toughness of the alloy decreases and the brittleness increases, which will lead to the armor-piercing projectile breaking before completely penetrating the target; when the content of microcracks is too low, it is not easy to affect the shear properties, and at this time, the tungsten alloy with microcracks is no different from the conventional tungsten alloy, and mushroom heads are still likely to be generated during the armor-piercing process. The present invention further precisely adjusts the process parameters of rotary forging and the content of microcracks to well balance the relationship between the two, and thus obtains a tungsten alloy armor-piercing projectile material with high strength and toughness and easy to produce adiabatic shear failure.

[0022] The second technical solution of the present invention: A tungsten alloy prepared by the above method.

[0023] The third technical solution of the present invention: An application of the above tungsten alloy as an armor-piercing projectile material.

[0024] The present invention discloses the following technical effects:

[0025] (1) The method of the present invention introduces a certain number of prefabricated microcracks into the tungsten skeleton of the alloy, and the microcracks form a random and uniform distribution state in the tungsten phase, solving the problem that a large number of W particles in the tungsten alloy are difficult to transgranularly fracture under dynamic deformation conditions and the adiabatic shear failure ability is poor.

[0026] (2) The typical rotary forging process is to increase the dislocation density and strength of the alloy to provide more strain energy for dynamic recrystallization, aiming to promote the generation of adiabatic shear bands. However, the generation of adiabatic shear bands is more related to the physical and chemical properties of the material itself, which can effectively increase the strength of the alloy but cannot directly promote shear failure. Because the essence of adiabatic shear failure is that a large number of W particles transgranularly fracture to form a main crack band under large deformation and high strain rate, and then failure occurs. The present invention precisely adjusts the process parameters of rotary forging to introduce microcracks, bringing shear main crack initiation points and connection points to the alloy, enabling the alloy to undergo shear failure at lower strain and strain rate, effectively reducing the "mushroom head" effect of tungsten alloy armor-piercing projectiles.

[0027] Cracks in alloy preparation can lead to a decline in the mechanical stability of materials and parts. This is mainly because the presence of microcracks causes a sharp reduction in the plasticity of the material (generally below 5%), resulting in brittle fracture problems. Therefore, in the prior art, efforts are made to avoid the generation of cracks during alloy preparation. In the present invention, through process adjustment before rotary forging, the toughness of the alloy before rotary forging is significantly improved, enabling the alloy to have a good microstructure. Then, by precisely adjusting the process parameters of rotary forging, even when the alloy has a certain number of small cracks, it can still have a plasticity of about 7-10%, avoiding the brittle fracture problem of the material. And through the setting of cracks, shear main crack initiation points and connection points are brought to the alloy, enabling the alloy to undergo shear failure at lower strains and strain rates, effectively reducing the "mushroom head" effect of tungsten alloy armor-piercing projectiles.

[0028] (3) The present invention regulates the content of prefabricated microcracks through rotary forging, optimizing the balance of static / dynamic mechanical properties of the alloy. Microcracks, as the initiation points of shear failure, can significantly enhance the adiabatic shear sensitivity, enabling the dynamic impact strength of the material to reach 1835-2072 MPa (strain rate of 2000 / s), while maintaining a quasi-static tensile strength ≥ 1270 MPa and an elongation rate ≥ 7%. The present invention solves the problem of reduced penetration ability caused by the difficulty of shear failure in traditional sintered tungsten alloys. During the armor-piercing process, through the coordinated expansion of microcracks to form a main crack band, the "mushroom head" effect is inhibited, providing a new approach for the engineering preparation of high self-sharpening armor-piercing projectile materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 FIG. is the micrograph of high-density tungsten alloys prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention, where (a) is Example 1, (b) is Example 2, (c) is Example 3, (d) is Comparative Example 1, and (e) is Comparative Example 2;

[0031] Figure 2 FIG. is the micrograph of the quenched high-density tungsten alloy prepared in Comparative Example 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0033] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0034] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0035] Without departing from the scope or spirit of the present invention, various improvements and variations can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and examples are merely exemplary.

[0036] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0037] In a first aspect of the present invention, a method for improving the self-sharpening of tungsten alloy by prefabricating microcracks is provided, including the following steps:

[0038] (1) Mix W powder, Ni powder and Fe powder evenly by an acoustic resonance (RAM) mixer and then dry them to obtain W-Ni-Fe powder;

[0039] The W-Ni-Fe powder, by mass percentage, includes the following components: 90 - 93% of W powder, 5 - 7% of Ni powder and 2 - 3% of Fe powder; the particle sizes of the W powder, Ni powder and Fe powder are all ≤ 5μm, and the purities are all ≥ 99.8%;

[0040] The acoustic resonance (RAM) mixer generates resonance based on a drive system and a spring system. Under the condition of a small input energy, the mixing container generates a low-frequency large-acceleration vertical vibration, and a coupling effect of macroscopic vibration mixing and microscopic acoustic streaming mixing is generated inside the materials to be mixed, so as to achieve high-efficiency mixing in a short time. The mixer is in an automatic mode, the resonance frequency is 50 - 70Hz, the acceleration is 50 - 60g, the mixing time is 5 - 7min, and the mass of the mixed powder per time is 500 - 700g;

[0041] The drying temperature is 80 - 100 °C, and the time is 8 - 10 h;

[0042] (2) Load the W-Ni-Fe powder into a cold isostatic pressing mold, perform manual compaction and sealing, and then place it in a cold isostatic pressing pressure vessel (oil pressure) for further pressing and forming to obtain a compact billet;

[0043] The pressure of cold isostatic pressing is 150 - 180 MPa, and the pressing time is 90 - 150 s;

[0044] (3) Heat the pusher-type hydrogen sintering furnace to 1100 - 1200 °C at a heating rate of 5 - 10 °C / min, then push the billet into the furnace, and keep it warm for 0.5 - 1 h for pre-sintering; then heat it to 1420 - 1470 °C at a heating rate of 5 - 10 °C / min and keep it warm for 1 - 1.5 h to achieve densification, obtaining a densified sample with a long rod shape, a diameter of 25 - 35 mm, and a length of 500 - 600 mm; then place the densified sample in a vacuum sintering furnace for dehydrogenation heat treatment to obtain a formed tungsten alloy billet;

[0045] The atmospheres for both pre-sintering and sintering are ammonia decomposition gas (the molar ratio of N and H is = 1:3);

[0046] The heating rate of dehydrogenation heat treatment is 5 - 10 °C / min, the temperature is 1100 - 1200 °C, and the holding time is 1 - 3 h;

[0047] Under the above conditions for pre-sintering and sintering, it is possible to avoid excessive grain growth while ensuring the density of the material.

[0048] (4) Perform rotary forging on the formed tungsten alloy billet to obtain a tungsten alloy (a high-density tungsten alloy with a suitable content of prefabricated microcracks);

[0049] Rotary forging includes: first heating to 550 - 600 °C at a heating rate of 5 - 15 °C / min, keeping it warm for 7 - 12 min, and then performing rotary forging at a rotary forging speed of 50 - 300 r / min.

[0050] The number of tungsten particles containing prefabricated microcracks in the tungsten alloy accounts for 7 - 17% of the total number of tungsten particles (the forging deformation increases from 0 - 30%, and the content of prefabricated microcracks also gradually increases from 0 - 30%), and the tungsten particles containing prefabricated microcracks are randomly distributed, and the microcracks have no orientation.

[0051] In the second aspect of the present invention, there is provided a tungsten alloy prepared by the above method.

[0052] In the third aspect of the present invention, there is provided an application of the above tungsten alloy as a penetrator material.

[0053] Example 1

[0054] A method for enhancing the self-sharpening property of tungsten alloy armor-piercing projectile materials by prefabricating microcracks:

[0055] (1) Using W powder, Ni powder, and Fe powder as raw materials, after weighing the raw materials in proportion, the W powder, Ni powder, and Fe powder are mixed evenly by an acoustic resonance (RAM) mixer (resonance frequency is 62 Hz, acceleration is 50 g, mixing time is 6 min, and the mass of the mixed powder per single time is 500 g), and then dried (temperature is 80 °C, time is 10 h) to obtain W-Ni-Fe powder;

[0056] Among them, for the W-Ni-Fe powder, by mass percentage, the composition is as follows: W powder is 91%, Ni powder is 6.3%, and Fe powder is 2.7%;

[0057] The average particle size of W powder is 2.36 μm, the average particle size of Ni powder is 2.3 μm, and the average particle size of Fe powder is 4.38 μm;

[0058] The purity of W powder, Ni powder, and Fe powder is all ≥99.8%;

[0059] (2) Put the W-Ni-Fe powder into a cold isostatic pressing mold, conduct manual compaction and sealing, and then place it in a cold isostatic pressing pressure tank (oil pressure) for further molding (pressure is 160 MPa, pressure holding time is 90 s) to obtain a compacted billet.

[0060] (3) Heat the pusher-type hydrogen sintering furnace to 1150 °C at a heating rate of 10 °C / min, then push the billet into the furnace, and keep it warm for 50 min to achieve pre-sintering; then heat it to 1430 °C at a heating rate of 5 °C / min and keep it warm for 75 min to obtain a densified sample with a long rod shape, a diameter of 30 mm, and a length of 600 mm.

[0061] Among them, the atmospheres for pre-sintering and sintering are both ammonia decomposition gas (molar ratio of N and H = 1:3).

[0062] (4) Place the densified sample in a vacuum sintering furnace for dehydrogenation heat treatment (heating rate is 10 °C / min, temperature is 1200 °C, holding time is 3 h) to obtain a formed tungsten alloy billet.

[0063] (5) Put the formed tungsten alloy billet into a muffle furnace, heat it to 600 °C at a heating rate of 10 °C / min, keep it warm for 10 min, and then put it into a rotary forging machine for rotary forging. The rotary forging speed is 80 r / min, and the forging deformation amount is 5% to obtain tungsten alloy armor-piercing projectile materials (high-density tungsten alloy).

[0064] The tungsten alloy armor-piercing projectile material prepared in this example was tested for its microstructure, room-temperature tensile properties, and dynamic mechanical properties. The results showed that the content of prefabricated microcracks in the tungsten alloy armor-piercing projectile material was 7% (the number of tungsten particles containing prefabricated microcracks / the total number of tungsten particles), the room-temperature tensile strength was 1270 MPa, the elongation was 10.2%, the dynamic impact strength was 1835 MPa (strain rate was 2000 / s), and the microstructure after dynamic impact ( Figure 1 Figure (a) in

[0065] Example 2

[0066] A method for improving the self-sharpening of tungsten alloy armor-piercing projectile material by prefabricating microcracks:

[0067] (1) Using W powder, Ni powder, and Fe powder as raw materials, after weighing the raw materials according to the ratio, the W powder, Ni powder, and Fe powder were mixed evenly by an acoustic resonance (RAM) mixer (resonance frequency was 62 Hz, acceleration was 50 g, mixing time was 6 min, and the mass of the mixed powder per time was 500 g), and then dried (temperature was 80 °C, time was 10 h) to obtain W-Ni-Fe powder;

[0068] Among them, for the W-Ni-Fe powder, by mass percentage, the composition was as follows: W powder was 91%, Ni powder was 6.3%, and Fe powder was 2.7%

[0069] The average particle size of the W powder was 2.36 μm, the average particle size of the Ni powder was 2.3 μm, and the average particle size of the Fe powder was 4.38 μm;

[0070] The purity of the W powder, Ni powder, and Fe powder was all ≥ 99.8%;

[0071] (2) The W-Ni-Fe powder was loaded into a cold isostatic pressing mold, manually compacted and sealed, and then placed in a cold isostatic pressing pressure tank (oil pressure) for further molding (pressure was 160 MPa, pressure holding time was 90 s) to obtain a compact billet.

[0072] (3) The pusher-type hydrogen sintering furnace was heated to 1150 °C at a heating rate of 10 °C / min, and then the billet was pushed into the furnace and held for 50 min for pre-sintering; then it was heated to 1430 °C at a heating rate of 5 °C / min and held for 75 min to obtain a densified sample in the shape of a long rod, with a diameter of 30 mm and a length of 600 mm.

[0073] Among them, the atmospheres for pre-sintering and sintering were both ammonia decomposition gas (molar ratio of N and H = 1:3).

[0074] (4) Place the densified sample in a vacuum sintering furnace for dehydrogenation heat treatment (heating rate: 10 °C / min, temperature: 1200 °C, holding time: 3 h) to obtain a formed tungsten alloy blank.

[0075] (5) Place the formed tungsten alloy blank in a muffle furnace, heat it to 600 °C at a heating rate of 8 °C / min, hold for 10 min, and then place it in a rotary forging machine for rotary forging. The rotary forging speed is 120 r / min, and the forging strain is 10% to obtain tungsten alloy armor-piercing projectile material (high-density tungsten alloy).

[0076] Test the microstructure, room-temperature tensile properties, and dynamic mechanical properties of the tungsten alloy armor-piercing projectile material prepared in this example. The results show that: the content of prefabricated microcracks in the tungsten alloy armor-piercing projectile material is 13% (the number of tungsten particles containing prefabricated microcracks / the total number of tungsten particles), the room-temperature tensile strength is 1352 MPa, the elongation is 7.8%, the dynamic impact strength is 1970 MPa (strain rate: 2000 / s), and the microstructure after dynamic impact ( Figure 1 Figure (b)) shows that obvious adiabatic shear failure occurs in the alloy, and the failure cracks are connected through the prefabricated microcracks in the tungsten alloy. The originally disordered microcracks show a unified directionality (shear direction). It is proved that the prefabricated microcracks effectively induce the cleavage of tungsten particles, initiate cracks, overcome the problem of difficult transgranular fracture, and promote shear failure.

[0077] Example 3

[0078] A method for improving the self-sharpening of tungsten alloy armor-piercing projectile material by prefabricating microcracks:

[0079] (1) Using W powder, Ni powder, and Fe powder as raw materials, after weighing the raw materials in proportion, mix the W powder, Ni powder, and Fe powder evenly by an acoustic resonance (RAM) mixer (resonance frequency: 62 Hz, acceleration: 50 g, mixing time: 6 min, single mixing powder mass: 500 g), and then dry (temperature: 80 °C, time: 10 h) to obtain W-Ni-Fe powder;

[0080] Among them, the composition of the W-Ni-Fe powder, by mass percentage, is as follows: W powder is 91%, Ni powder is 6.3%, and Fe powder is 2.7%;

[0081] The average particle size of the W powder is 2.36 μm, the average particle size of the Ni powder is 2.3 μm, and the average particle size of the Fe powder is 4.38 μm;

[0082] The purity of the W powder, Ni powder, and Fe powder ≥ 99.8%;

[0083] (2) The W-Ni-Fe powder is filled into a cold isostatic pressing mold, manually compacted and sealed, and then placed in a cold isostatic pressing pressure vessel (oil pressure) for further pressing into shape (pressure: 160 MPa, pressure holding time: 90 s) to obtain a compacted blank.

[0084] (3) The pusher-type hydrogen sintering furnace is heated to 1150 °C at a heating rate of 10 °C / min, and then the blank is pushed into the furnace and kept warm for 50 min to achieve pre-sintering; then it is heated to 1430 °C at a heating rate of 5 °C / min and kept warm for 75 min to obtain a densified sample in the shape of a long rod, with a diameter of 30 mm and a length of 600 mm.

[0085] Among them, the atmospheres for both pre-sintering and sintering are ammonia decomposition gas (molar ratio of N to H = 1:3).

[0086] (4) The densified sample is placed in a vacuum sintering furnace for dehydrogenation heat treatment (heating rate: 10 °C / min, temperature: 1200 °C, heat preservation time: 3 h) to obtain a formed tungsten alloy blank.

[0087] (5) The formed tungsten alloy blank is placed in a muffle furnace and heated to 570 °C at a heating rate of 10 °C / min, kept warm for 10 min, and then placed in a rotary forging machine for rotary forging. The rotary forging speed is 150 r / min, and the forging strain is 15% to obtain tungsten alloy armor-piercing projectile material (high-density tungsten alloy).

[0088] The tungsten alloy armor-piercing projectile material prepared in this example is tested for its microstructure, room-temperature tensile properties and dynamic mechanical properties. The results show that: the content of prefabricated microcracks in the tungsten alloy armor-piercing projectile material is 17% (the number of tungsten particles containing prefabricated microcracks / the total number of tungsten particles), the room-temperature tensile strength is 1438 MPa, the elongation is 7.1%, the dynamic impact strength is 2072 MPa (strain rate: 2000 / s), and the microstructure after dynamic impact ( Figure 1 figure (c)) shows that the adiabatic shear failure behavior of the alloy is further aggravated, and the alloy still has good ductility and plasticity.

[0089] Comparative Example 1

[0090] Same as Example 1, the difference is only that in step (5), specifically: the formed tungsten alloy blank is placed in a muffle furnace and heated to 650 °C at a heating rate of 10 °C / min, kept warm for 10 min, and then placed in a rotary forging machine for rotary forging. The rotary forging speed is 50 r / min, and the forging strain is 5% to obtain tungsten alloy armor-piercing projectile material (high-density tungsten alloy).

[0091] The tungsten alloy armor-piercing projectile material prepared in this comparative example was tested for its microstructure, room-temperature tensile properties, and dynamic mechanical properties. The results showed that the content of prefabricated microcracks in the tungsten alloy armor-piercing projectile material was 4% (the number of tungsten particles containing prefabricated microcracks / the total number of tungsten particles), the room-temperature tensile strength was 1138 MPa, the elongation was 10%, the dynamic impact strength was 1687 MPa (strain rate was 2000 / s), and the microstructure after dynamic impact ( Figure 1 Figure (d)) showed that there was no obvious shear failure phenomenon in the alloy.

[0092] Comparative Example 2

[0093] Same as Example 1, the difference is only that in step (5), specifically: the formed tungsten alloy billet was put into a muffle furnace, heated to 550 °C at a heating rate of 10 °C / min, held for 10 min, and then put into a rotary forging machine for rotary forging. The rotary forging speed was 200 r / min, and the forging deformation was 20% to obtain the tungsten alloy armor-piercing projectile material (high-density tungsten alloy).

[0094] The tungsten alloy armor-piercing projectile material prepared in this comparative example was tested for its microstructure, room-temperature tensile properties, and dynamic mechanical properties. The results showed that the content of prefabricated microcracks in the tungsten alloy armor-piercing projectile material was 24% (the number of tungsten particles containing prefabricated microcracks / the total number of tungsten particles), the room-temperature tensile strength was 1090 MPa, the elongation was 1.9%, the dynamic impact strength was 1850 MPa (strain rate was 2000 / s), and the number of prefabricated microcracks in the alloy increased significantly ( Figure 1 Figure (e)), resulting in an increase in the brittleness of the alloy, and brittle fracture occurred even during small deformations, which was not conducive to armor piercing.

[0095] Comparative Example 3

[0096] Same as Example 1, the difference is only that in step (5), specifically: the formed tungsten alloy billet was put into a glass tube, argon was introduced, and it was sealed to prevent oxidation. Then it was put into a muffle furnace, heated to 500 °C at a heating rate of 8 °C / min, and then heated to 1200 °C at a heating rate of 5 °C / min, held for 3 h, and then quenched with water to obtain the tungsten alloy armor-piercing projectile material (quenched high-density tungsten alloy).

[0097] The tungsten alloy armor-piercing projectile material prepared in this comparative example was tested for its microstructure, room-temperature tensile properties, and dynamic mechanical properties. The results showed that the content of prefabricated microcracks in the tungsten alloy armor-piercing projectile material was 4% (the number of tungsten particles containing prefabricated microcracks / the total number of tungsten particles), the room-temperature tensile strength was 891 MPa, the elongation was 6.3%, and the dynamic impact strength was 1569 MPa (the strain rate was 2000 / s). At this time, only a small number of microcracks existed in the alloy, but the comprehensive strength and plasticity performance of the alloy was far inferior to that of the example, and the strength was also lower than that of Comparative Examples 1 and 2. Its comprehensive mechanical properties decreased, and brittle fracture occurred during small deformations, which was not conducive to armor piercing.

[0098] The micrograph of the quenched high-density tungsten alloy prepared in this comparative example is shown in Figure 2 .

[0099] The room-temperature tensile properties and dynamic properties of the high-density tungsten alloys prepared in the above examples and comparative examples are shown in Table 1.

[0100] Table 1 Room-temperature tensile properties and dynamic properties of high-density tungsten alloys

[0101]

[0102] The above-described examples are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for improving the self-sharpening property of tungsten alloy by prefabricating microcracks, characterized in that, The method includes the following steps: Subject the formed tungsten alloy green body to prefabricated microcrack treatment to obtain tungsten alloy; The number of tungsten particles with prefabricated microcracks in the tungsten alloy accounts for 7-17% of the total number of tungsten particles.

2. The method according to claim 1, wherein The preparation method of the formed tungsten alloy green body includes the following steps: Mix W powder, Ni powder and Fe powder evenly and then press them into a blank; Subject the blank to pre-sintering and sintering, and then perform dehydrogenation heat treatment to obtain the formed tungsten alloy green body.

3. The method according to claim 2, wherein The blank, by mass percentage, includes the following components: 90-93% of W powder, 5-7% of Ni powder and 2-3% of Fe powder.

4. The method according to claim 2, characterized in that, The pressing is cold isostatic pressing, the pressing pressure is 150-180 MPa, and the pressing time is 90-150 s; And / or, the temperature of the pre-sintering is 1100-1200 °C, the heat preservation time is 0.5-1 h, and the atmosphere is ammonia decomposition gas; And / or, the temperature of the sintering is 1420-1470 °C, the heat preservation time is 1-1.5 h, and the atmosphere is ammonia decomposition gas.

5. The method according to claim 2, wherein The heating rate of the dehydrogenation heat treatment is 5-10 °C / min, the temperature is 1100-1200 °C, and the heat preservation time is 1-3 h.

6. The method according to claim 1, wherein The method adopted for the prefabricated microcrack treatment includes rotary forging.

7. The method according to claim 6, wherein The rotary forging includes: first heating at a heating rate of 5-15 °C / min to 550-600 °C, holding for 7-12 min, and then performing rotary forging at a rotary forging speed of 50-300 r / min.

8. A tungsten alloy prepared by the method according to any one of claims 1-7.

9. An application of the tungsten alloy according to claim 8 as a material for armor-piercing projectiles.

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