Study On Twin-Roll Casting Processing And Structure Property Of 7075 Aluminum Alloy

7075 Al alloy is one of the most important alloys in Al-Zn-Mg-Cu series, which is a kind of heat treatment strengthening aluminium alloy, Because of its high strength and high toughness, high stress structure in the field of aviation and spaceflight is mainly used.Twin roll casting is one of advanced technology in the process of aluminum alloy,it combine traditional casting with rolling process and it has the advantages of short process, low cost and so on. At present, for the 7075 aluminum alloy production and processing methods are mainly casting, rolling, extrusion,etc.However,7075 twin roll casting process is still in the experimental stage.In this paper, 7075 aluminum alloy sheets were prepared by twin roll casting method. Study on the optimum technological conditions of twin roll casting through multi group experiments,and the influence of different technological parameters on the microstructure and properties of cast rolling plate was studied.By means of OM,SEM, EDS of 7075 aluminum alloy cast rolling plate, 7075 aluminum alloy ingot casting and Cast rolling plate after heat treatment are tested and analyzed, at the same time, UTM5305 electronic universal testing machine and Vivtorinox hardness tester were used to test mechanical properties and hardness of cast rolling plate.Through multi group experiments, When pouring temperature is 993 K,The faster the cast rolling speed, the worse the formability of the cast rolling plate,the coarser the grain of cast rolling plate become,the worse mechanical properties it has. When the pouring temperature is 963K-973 K,the faster the cast rolling speed, the smaller the grain size, and the better mechanical properties of the cast rolling plate.7075 cast rolling plate was prepared by the experimental system, which is composed of dendrite on the edge and equal axis crystal in center,Grain size increases from surface to core,the cast rolling characteristics of surface grain is the most obvious.The second phase existence both in the grain boundary and the crystal,And the second phase precipitation in the surface layer is greater than that of the core.After cast rolling, the maximum hardness of the alloy is 130.9HV,the maximum tensile strength is283.8MPa.The second phase in the microstructure of cast rolling plate is obviously reduced after solid solution treatment,and grain boundaries are obviously refined,the mechanical properties of cast rolling plate are also improved. And the dissolution phenomenon of sample is obviously after aging treatment.Test of its hardness,aging treatment has great effect on the hardness of the sample,the hardness can reach164.7HV after aging treatment.