Evolution of Microstructure and Mechanical Properties During Aging Process of 7075 Aluminum Alloy
The 7075 aluminum alloy was subjected to homogenization treatment,solution treatment and single-stage aging treatment with different aging time of 0 to 24 h.The effects of aging time on the micro-structure and mechanical properties of 7075 aluminum alloy were studied by electron backscatter diffraction(EBSD)analysis,Vickers hardness test and room temperature tensile test.The results showed that the 7075 aluminum alloy after aging treatment exhibited equiaxed grain structure.With the extension of aging time,the grain size,the proportion of small angle grain boundaries,hardness,tensile strength and elonga-tion after fracture all showed a trend of increasing first and then decreasing or maintaining stability.When the aging time was 8 h,the grain size reached the maximum of 25.6 μm,and then maintained at 20.9 to 22.4 μm.The proportion of low-angle grain boundaries reached the maximum of 44.52％,and then de-creased to 25.19％after aging for 24 h.The hardness reached 172.6 HV,and then maintained at 172.6 to 175.2 HV.When the aging time was 4 h,the tensile strength and elongation after fracture reached the maximum values,which were 552.0 MPa and 36.2％,respectively,and then decreased with the further aging time.
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