关键词: 7A75铝合金, 厚度梯度, 织构, 力学性能

Abstract: Microstructure evolution and mechanical properties at different thickness of as-hot rolled 7A75 aluminum after solution treatment were investigated.The microstructure,crack propagation and fracture morphologies were characterized by using OM and SEM.The texture constitution and residual stress were analyzed by using XRD,and the mechanical properties were tested by using tensile tester.The results indicate that at different thickness of the 7A75 aluminum alloy,the yield strength at surface,1/4 thickness and center are 200,200 and 185 MPa,while tension strength is 345,335 and 325 MPa respectively,but the elongation is 20%,19.5% and 22% respectively,which show that the center layer has the lowest strength and the highest elongation.The average grain size at surface,1/4 thickness and center are about 24.5,24.8 and 25.5 μm respectively,which are all within the range of 24-26 μm and no obvious difference.There are obvious plane strain texture which distributing along β orientation line at surface,mainly Copper texture {112}<111>at 1/4 thickness and weakened β orientation line texture at center.The residual stress at surface,1/4 thickness and center are -18.5,-3.5 and 7.5 MPa respectively,which show a compressive stress at surface and 1/4 thickness and a tensile stress at center.

Key words: 7A75 aluminum alloy, thickness, texture, mechanical properties