Research On Hot Extrusion Forming Process Of Aluminum Alloy Cartridge

Reducing cartridge case weight is one of the most effective method way to realize the lightweight of small arms equipment.As the preferred material,aluminum alloy can effectivly reduce the weight of cartridge case,improve the efficiency of individual combat,aluminum alloy cartridge case forming technology and technics has been the focus in the lightweight ammunition research at home and abroad.But there are many difficulties in the cartridge case forming process owing to the poor large plastic deformability of high strength aluminum alloy with its low extrudability and elongation.7050 aluminum alloy was selected as the experimental material,the hot extrusion process of cartridge case was researched comprehensively by numerical simulation and experiment in this paper.Firstly,extrusion blank,mould structure and outline dimension were designed based on the structure characteristics of aluminum alloy cartridge case,The hot extrusion process of cartridge case was simulated by using DEFORM software.The effective stress,effective strain,temperature,damage,velocity and metal flowing law were analyzed,the effect of'extrusion temperature and velocity on the extrusion process was discussed,the extrusion process parameters was optimized,simulation results show that deformation is inhomogeneous in the cartridge case hot extrusion process,fluidity is different at different area,deformation is intense at the wall of the cartridge case,but small at the bottom of the cartridge,fluidity is also different between the surface and center of the wall,the deformation nonuniformity increases when extrusion velocity rises,the deformation resistance decreases when temperature rises,the adequate extrusion temperature is 450 ?,extrusion velocity is 5mm/s.Secondly,the homogenization of the aluminum alloy blank was researched,experiments prove that the simulation is feasible and accurate,the cartridge case obtained in the hot extrusion experiments have a good surface quality,the shape,physical dimension and wall thickness of the extrusion cartridge case are satisfactory.At last,the influence of the hot extrusion on the aluminum alloy microstructure and mechanical properties were investigated by metallographic experiment,hardness and tension test,it shows that the hot extrusion process can remarkably refine the grain structure of 7050 aluminum alloy,the grain flow is clearly visible,ultimate strength of cartridge case is 614MPa which has been improved obviously,elongation just decreases a little.The feasibility of hot extrusion for aluminum alloy cartridge case was verified,the foundation for further research and industry application was set up...