Abstract: Effect of cold rolling deformation on microstructure and mechanical properties was investigated, the mechanism of second phase particles simulated nucleation was discussed. The microstructure was characterized by using OM and TEM. The mechanical properties were tested by using tension tester machine. The IE value was tested by using sheet forming test machine. The results indicate that the strength and elongation increases with the increase of deformation, and the increase rate of yield strength is higher than tensile strength. When the deformation is 50%, the yield strength and tension strength reach 435 MPa and 460 MPa respectively, which have an increase of 190 MPa and 110 MPa respectively compared to those without deformation. Meanwhile, the elongation increases to 14%, and the IE value also increases with the increase of deformation. When the deformation is 30%, 50% and 70%, the average grain size is about 31.5, 13.5 and 13.0 μm respectively, which shows that the greater the deformation, the smaller and more uniform the matrix grain size. The precipitation phase MgZn₂ lager than 0.5 μm simulates the nucleation of recrystallization grain after cold rolling process during the solution treatment, while the ones which has the size of 50-100 nm pins the grain boundaries and inhibits the growth of recrystallization grains.

Key words: 7A75 aluminum alloy, cold rolling, microstructure, precipitation simulated nucleation effect