After decades of continuous research and development, large-caliber high-density tungsten alloy armor-piercing projectiles have become the main type of ammunition for main battle tanks and large-caliber anti-tank guns. However, with the improvement of the armor protection level of main battle tanks in various countries, With the continuous improvement, new reactive armor has a certain ability to resist armor-piercing projectiles. Especially the emergence and application of ultra-high-speed kinetic energy projectiles have put forward increasingly higher requirements for the mechanical properties of high-density armor-piercing projectile core materials.
Over the years, while trying to improve the performance of tungsten alloy elastic cores at home and abroad, they have also carried out research and exploration on various composite elastic cores, trying to use various composite materials prepared with high-density wires or fibers. Materials are used to further improve the strength and toughness of armor-piercing projectiles, and the most studied one is to use tungsten wire bundles to prepare high-density composite armor-piercing projectile cores.
These studies mainly include the following two aspects: on the one hand, under the existing alloy system and process conditions, the best armor-piercing performance can be obtained by optimizing the alloy composition and process parameters, or by designing new Alloy systems, adding alloying elements or developing new processes to obtain higher performance alloys.
On the other hand, extensive research work has been carried out at home and abroad on the deformation strengthening and pre-strain aging of tungsten alloys. Among them, the rotational forging process has been widely used in the production of large-diameter bullet cores, and The application of hydraulic extrusion technology to small-caliber bullet cores has achieved satisfactory results.
Pre-strain aging can greatly improve the strength of tungsten alloy while ensuring that the material has good toughness. However, due to the lack of breakthroughs in research on its strengthening and toughening mechanism, and its processing performance is not stable enough, it has not been used in standard weapons. on the application.
In addition, some people have also conducted research on a variety of new process methods for strengthening and toughening tungsten alloys: such as plasma melting-rapid solidification method, hydrometallurgy-plasma melting method and activated spray thermal decomposition method. These methods can produce very uniform pre-alloyed powder. When sintering high-density tungsten alloys with these "pre-alloyed powders", the sintering temperature can be lowered and the sintering time shortened, so that the alloy has both higher strength and better properties. toughness.
In summary, although after decades of continuous research, the strength and toughness of high-density tungsten alloys have been greatly improved, but for future ultra-high-speed kinetic energy projectiles that require large penetration depth The problem of insufficient strength and toughness of armor-piercing bullets has not been fundamentally solved. Therefore, the development of armor-piercing bullet cores of other high-density materials, especially the development of high-density composite armor-piercing bullet cores, has attracted great attention from industrialized countries, and research It is also getting wider and deeper.
The British Royal Arsenal uses certain tungsten alloy wires as reinforcements. Feasibility studies have been conducted for armor-piercing projectiles. Experiments have shown that it is necessary to coat some oxides on the surface of the alloy wire to prevent the reinforcement phase from reacting with the matrix during the sintering process.
Germany has conducted research on making armor-piercing bullets from wire bundles. The method is to deposit bonding phase metal on heavy metal wires, then sinter them together, and then forge or roll them. In addition, experimental research was conducted on the mechanical composite process method of loading heavy metal wires into sintered tungsten alloy tubes and forging them.
The process used by Japanese steel mills to develop wire-tow composite armor-piercing projectiles is to plate a variety of bonding phase elements on the wires, and then perform liquid-phase sintering to produce an armor-piercing projectile core blank.
Some domestic research institutes and colleges have also carried out various tungsten wire bundles.
A U.S. Navy patent announced a more economical manufacturing process for steel-tungsten composite armor-piercing projectiles. The process method is to evenly distribute tungsten alloy reinforced wires with a certain small diameter in parallel using a wire harness collimator, put the collimator and reinforced wires together into a rubber sheath, and then add B0 steel powder pre-mixed with -203 graphite powder .
The rubber sleeve is closed and cold isostatically pressed. After removing the sleeve and collimator, the pressed part is sintered in a hydrogen atmosphere to make the blank dense. The blank is then forged with tungsten wire. The arrangement will undergo some changes, and the distance between the wires will decrease, but the overall dimensions of the wires will remain basically unchanged. After the blank is bodyed, quenched and tempered, its hardness can reach a very high level.