Tungsten Copper EFP Liner Manufacturing Process

Tungsten copper EFP liner, EFP is abbreviation of Explosively Formed Penetrator, which is “explosively formed piercing warhead” or “self forging fragmentation warhead”, some countries also known as P Charge (Projectile Charge), Misznay-Schardin Charge and mass shaped charge and so on. A typical EFP warhead consists of a metal liner, housing, as well as booster explosive components consisting of a series, there is usually a cover for drug and explosive type of pressure ring assembly is secured. It relies on the projectiles with high kinetic energy to armor, compared with conventional HEAT projectile with charge jet, in the high explosive detonation, the energy generated by the blast occurred folded by deforming Liner and get high speed, because the speed difference the presence of eventually forming a penetrator.

The explosively formed projectile EFP here we are introducing is also one of a kind shaped charge, it uses more than 120 ° cone angle hemispherical cap or hyperbolic Liner conduct charge. After the explosion, tungsten copper liner extruded by great load and after flip closed to form explosively formed projectile. And it has many advantages, such as less interferes to reactive armor, great penetration aftereffect and be insensitive to the height of burst. So the capacity of armor and penetrate highly depends on the materials of liner.

The conventional materials of liner include iron, copper, depleted uranium, tantalum and so on. Pure iron and pure copper has excellent plasticity, but their density is lower, which reduces the kinetic energy of projectile formed and the penetration force of the target material; the depleted uranium has a high density and plasticity, can greatly enhance the strength and armor-piercing Immunity range of thousands of degrees of high temperature burning effect, but the depleted uranium is still radioactive material, and it is harmful to human health; tantalum element is a kind of rare-earth element, it has the ability of penetration is much greater than copper and iron, but its high cost problems that have hindered the promotion of the use of the important factors.

By comparison, tungsten copper W-Cu system combines high hardness, high density, high strength and excellent chemical properties of W and excellent thermal conductivity of and plasticity of Cu. Since there is a big difference between W and Cu (W-3410℃，Cu-1083℃), After the explosion of copper is evaporated leaving a high hardness, high density hard phase tungsten, compared to copper Liner armor penetration depth can be increased by nearly 30%. Therefore, tungsten copper EFP liner has a broad application prospect in the future. Ordinary tungsten powder, copper powder and ultra-fine tungsten-copper composite powder prepared tungsten copper EFP Liner and its performance was compared. Wherein ultrafine tungsten copper composite powder is prepared by using spray pyrolysis, it uses a proportion of copper nitrate and ammonium metatungstate dissolved in distilled water into the mixed solution, and then the pressure centrifugal spray drier precursor powders, the precursor powder is then placed in roasting reduction furnace. Finally, wet ground and placed in a ball mill reduction in the reduction furnace, ultra-fine tungsten-copper composite powder particle size is formed between 100-300nm.

After the tungsten copper rod made of tungsten copper EFP started liner blank forging, which blank deformation has three steps: 1. upsetting the blank in the mold, in this process the blank upper and lower parts deformation occurs first, and upper and lower portions of the pores gradually become less under the influence of compressive stress, density increases, increasing the contact area with the punch, friction force increases, under the action of the metal tensile stress generated lateral flow; 2. metal flows hindered by the mold wall and it will flow along with the hole of the mold bottom, and in the process the pores reduces and the density increases; finally, when the metal flow to the ejector rod will enter the multi-pressure stage, mainly through its hydrostatic pressure to eliminate rough pores, so the effect is not significant.

In addition, in the process of tungsten copper EFP liner blank forging, there are two ways of deformation of the matrix material, one is only copper phase deformation, deformation does not occur with tungsten and tungsten particles along the direction of deformed copper matrix flow was streamlined distribution; the other one is both of Cu and W phase have deformation and form fibrous structure. In order to ensure that the final density, tensile strength and elongation to achieve the desired requirements, we should make a reasonable design for tungsten copper EFP liner shape and have sufficient deformation.