Effect Of Different Extrusion Ratio On Follow - Up Process Of Spray Forming 7075 Aluminum Alloy

The low comprehensive properties of 7075 aluminum alloy prepared by spray forming technology need to the subsequent deformation and heat treatment processing to improve performance. Extrusion ratios have an impact on material microstructure, and the subsequent heat treatment is related to microstructure. Therefore, this article explored the influence of subsequent treatment to provide a theoretical basis for the actual production.In this study, the microstructure of extruded and heat treated alloy were analyzed by using microscopy(OM),SEM,XRD and tensile properties. The results showed as follows:The deposited ingot treated by different ratio extrusion process, and the primitive grain boundary is vanished. As the extrusion ratio increases, the distortion degree of grains is bigger, the mechanical properties of the alloy become better. However, the change of extrusion ratio can result in different internal energy storage, this process lead to the highly possibility of recrystallization. The state of aluminum alloy treated by extrusion ratio 8 complete recrystallization temperature and time is 510℃×0.5h. Extrusion ratio 32 is 460℃×2h. Extrusion ratio 60 is 440℃×1h.As the extrusion ratio changes, the solution temperature and time also have changed. The extrusion ratio 8 aluminum alloy has the best solution process is 490℃×1h. The extrusion ratio 32 alloy is 460℃×1h. The extrusion ratio 60 alloy is 435℃×1h.7075 aluminum alloy has a significant effect on ageing precipitation, and the phenomenon can be applied to different extrusion ratios aluminum alloy. The best peak ageing is 120℃×24h under different extrusion ratio. The mechanical properties of extrusion ratio 60 is worse than others because of no sufficient solution, large number of coarse second phase, and big size of coarse second phase. In the process of double ageing, the ageing temperature of the second step ageing has the most significant influence on the tensile strength and Vickers hardness and the first step ageing temperature has the most significant influence on the elongation. Compared with the peak aging, the mechanical properties of different extrusion ratio alloy have different degrees of decline after double ageing. The extrusion ratio 8 aluminum alloy has the best double ageing process is 130℃×4h+150℃×12h. The extrusion ratio 32 and 60 alloy have the best double ageing process is 130℃×3h+150℃×12h.