Effect Of Heat Treatments Before Cold Rolling On Microstructure And Mechanical Properties Of 6016 Aluminum Alloy

Aluminum alloy is a key material for lightweight automobile and 6016-T4P aluminum alloy sheet has been proved to be suitable for stamping forming of automobile exterior body panels.In this work,the effect of solution and over-aging treatments before cold rolling on textures of cold-rolled 6016 aluminum alloy sheet and the mechanical properties,microstructure and textures of 6016-T4P sheet was explored by tensile testing,electron backscattered diffraction,scanning electron microscope and transmission electron microscope.The main results are as follows:(1)Compared with the 6016 aluminum alloy sheet without heat treatment before cold rolling,the 6016 aluminum alloy sheet additional solution treatment and two-step over-aging treatment before cold rolling could affect the intensity and type of cold rolling texture.Additional solution treatment before cold rolling could enhance the intensity of S texture and B texture while additional two step over-aging treatment before cold rolling could reduce the intensity of S texture in cold-rolled 6016 aluminum alloy sheet.(2)Additional solution treatment before cold rolling could increase the strength,plasticity,and planar anisotropy of 6016-T4P aluminum alloy sheet while additional two-step over-aging could reduce plastic and planar anisotropy of 6016-T4P aluminum alloy sheet.(3)Additional solution treatment before cold rolling could refine and homogenize the recrystallized grain while additional two-step over-aging could increase the grain size and make the distribution of small angle grain boundary inhomogeneous.(4)Additional solution treatment before cold rolling could enhance the intensity of recrystallization textures and main texture is Cube texture.On the contrary,additional two-step over-aging treatment before cold rolling could decrease the intensity of recrystallization texture and produce CubeND texture and E texture.(5)Strong intensity of S texture in cold-rolled 6016 aluminum alloy sheet prepared by solution treatment before cold rolling leads to strong intensity of Cube texture in 6016-T4P sheet,then results in the high planar anisotropy.However,the large size precipitations introduced by two-step over-aging treatment contributes to weak intensity of S textures in cold-rolled 6016 aluminum alloy,and results in the weak intensity of recrystallization texture and the formation of recrystallization texture through particle stimulated nucleation of recrystallization,hence reducing the planar anisotropy of 6016-T4P sheet.