7075 Aluminum Alloy Spray Deposition Continuous Extrusion

7075 aluminum alloy semi-finished products are major in the form of plates, rods, profiles and forgings, because of its high strength, good anodic reaction, which is widely used in the field of aircraft structural components important force, hollow fixtures, trucks, tower buildings, ships, pipelines, etc. Such as:gears and shafts, fuse parts, meter shafts and gears, missile parts jumped valve, turbo, keys, etc. If with fine grains of 7075, then the better the performance of deep drilling, tool wear, thread rolling distinctive. The aviation industry for lightweight alloys have a lot of demand. But 7075 because of its low melting point eutectic phase of existence makes it very difficult to carry out thermal processing.Spray deposition is a refinement of grain size, increase the solubility of the preparation method of high-strength alloy 7075. By spray deposition continuous extrusion processing 7075 alloy can make the processes shortened greatly than conventional spray deposition and densification. In the 7075 manufacturing process,it was found that during extrusion there were skin cracks and peelings, just the beginning of even squeeze past. In this paper, to solve this problem have done a lot of research and testing, and optimization of preparation parameters are summarized in continuous exploration, the specific contents are as follows:(1) Double plates flow controllers use different parameters in the preparation of 7075 and analyzed to improve on their problems, mold preheat temperature is too high (500℃) will cause the material to burst.(2) On the phenomenon of crack problems have been studied and found that cracks are mainly caused by extrusion temperature is too high or too low and generated from the skin because of the atmosphere combined with a wide range of hot liquids produced. The position of cracks were found, there must be cracks in the rod material at 70.89%-73.08%, I believe that this phenomenon is not simply caused by the extrusion temperature is too high or too low, and the extrusion process characteristics are very great relationship, this conclusion on the future of the preparation of the rod material of great reference value.(3) The peeling phenomenon was studied, compared the phenomena of peeling with the tests without peeling,there goes the conclusion:the high temperature metal,and a wide range of atmosphere to form pores, and then in the extrusion process formed. When the rod material from the skin blistering were tested, it isfound that peeling phenomenon has little effect on performance.(4) On the second and sixth test rod material processed by solid solution on 460℃ with water quenching and aging for 9h,6h,30h respectively,changes in material strength is similar as the aging behavior of 7475 by Yan Da Jing. In the study it is found that the hardness of the materials and tensile strength does not reflect the changes.(5) 7075 cast of solid solution hardening and T651 handle discovery:the original cast of the grain boundary is a network structure; the solution after precipitation hardening and grain boundary regions facing the central area between the center of the grain boundary and grain partial together, this time the grain boundary for sparse point connections; under T651 state, precipitates at the grain boundary segregation, but did not form a mesh distribution phase precipitates in the grains also disperses.(6) On the basis of numerous experiments, the test parameter is set to die preheating temperature of 350℃, spray distance 400mm, funnel flow 60s/L, the melting temperature of 800℃, pressure 0.25MPa, the wheel speed 7.94r/min, squeeze when the ratio is 14.2,so the bar material was prepared.The tensile strength of the material prepared lever reach 396.70MPa, elongation of 11.77%. The heat treatment T651 intensity state corresponding to 525.56MPa, elongation of 14.46%.