Research On The Heat Treatment Process And Optimization Of Forming Process Of 7050aluminum Alloy Cartridge

7050 aluminum alloy has the advantages of light weight, high strength and easy processing characteristics, and aluminum alloy cartridge can replace the traditional copper cartridge and steel cartridge, so the development of aluminum alloy cartridges’ high performance that is one of the most important topics of lightweight small arms, has an important significance for national defense. Aluminum alloy cartridge development difficulty mainly lies in:a) Aluminum alloy poor plasticity at room temperature, which increases the difficulty of plastic processing; b) Aluminum alloy solid solution treatment and aging treatment system determines the mechanical properties and the corrosion resistance of the cartridge, so developing a suitable heat treatment system with the outstanding performance of low-temperature storage and high temperature using properties is very necessary. This paper mainly includes two parts: the optimization of aluminum alloy cartridge plastic forming process and the heat treatment system of the 7050 aluminum alloy cartridge.① The optimization of aluminum alloy cartridge plastic forming processWith using the finite element software, the plastic forming process of extrusion and bottom punching has been simulated and analyzed. For the different problems appeared in the plastic forming process, different methods has been used to optimize the structure of die as follows: a) With the using of BP neural network and genetic algorithm, the structure parameters of extrusion punch has been optimized, which greatly reduces the billet shear stress; b) Through the analysis of the stroke—load curve of drawing deformation process, parameters of pattern die have been optimized such as, the drawing punch radius, the radius dimension of die ring and the distance between two die rings. As a result, the residual damage value of the billet has been reduced. c) Through the analysis of the results of numerical simulation of the bottom punching deformation process, the clearance between punch and die has been optimized. And because of the elimination of the phenomenon of the cartridge wall thickness uneven, the cracking problem has been solved.②The development of 7050 aluminum alloy heat treatment systemIn order to explore the suitable heat treatment system of the 7050 aluminum alloy shell, this paper discusses and compares the single solution and two-stage solution system, single aging and two step aging on the mechanical properties of the alloy, the corrosion resistance. The rules can be found in the experimental results, as follows: a) Compared with the single solution system, the mechanical properties of the alloy after double stage solution treatment has greatly increased. The hardness(191HV) and electrical conductivity( 40.46%IACS)of the alloy was the best, when the second stage solution temperature is 485℃; the tensile strength(590MPa)and the elongation(14.04%) was the best, when the 2nd stage solution temperature is 495℃; b) After long time aging 120℃/8h+160℃, compared the alloy that the second solid solution temperature is 485℃ with the alloy that second solid solution temperature is 495℃,the tensile strength increased by 20 MPa, the elongation is increased by about 2%; c) Through the determination of aging kinetics curve, the first ageing peak time was 8h, the second peak aging time is16 h,when the second stage aging time is 24 h, the alloy has the best corrosion resistance. The heat treatment system of the 7050 aluminum alloy is determined as 450℃/1h+495℃/1h+120℃/8h+160℃/24 h.