Influences of aging temperature and time on microstructure and mechanical properties of 6005A aluminum alloy extrusions

The influences of aging time and aging temperature on the microstructure and mechanical properties were investigated on the 6005A aluminum alloy extrusions. Artificial aging was performed on the alloy extrusions. The aging times were 4, 8 and 12 h, and the aging temperatures were 150, 175 and 200 degrees C. The results show that the morphologies of the coarse Al(Fe,Cr) Si particles formed in the extrusion process are evolved from granular to rod-like particles with the increase of the aging temperature or the aging time. The volume fraction of the submicron precipitates reaches the maximum value at the aging temperature of 175 degrees C. AlFeSi particles in size of 1-3 mu m are precipitated at the grain boundaries at the aging temperature of 200 degrees C. The room temperature mechanical properties of the extrusions are more sensitive to the aging temperature than to the aging time. The optimum and stable mechanical properties are achieved when the aging procedure 175 degrees C, 4-8 h has been performed on the extrusions. The tensile strength and the yield strength in the longitudinal direction of the aged extrusions are more than 300 MPa and 270 MPa, respectively.