Microstructure and Mechanical Properties of Extruded AZ31 Profile with High Performance

Based on the advantages of Mg alloys, AZ31 alloy profiles were designed for mobile phones cell, and cars, which expanded Mg alloy application and achieved the purpose of environmental protection and energy saving. Tensile strength of the profile reached to 256 MPa, and elongation was 17.9%. The effects of different heat treatment parameters on microstructure and plastic property of AZ31 alloys profiles were studied. After aging heat treatment (T5), the comprehensive mechanical properties at room temperature of the profiles increased. The tensile strength reached to the maximum of 261 MPa, and the elongation reached to 14.3%, after ageing at 225 degrees C for 20h. The elongation reached the maximum value of 18.3%, however, the tensile strength decrease to 241 MPa, after aging at 175 degrees C for 15h. Moreover, the influence of cryogenic treatment on microstructure and plastic property of the AZ31 alloy profiles were studied. The results showed that elongation increased with the increase of treatment time, which would reach to 18.5% after cryogenic treatment. In addition, by cryogenic treatment and aging treatment, the tensile strength improved to 271 MPa. The cryogenic treatment improved obviously the plastic ability of AZ Mg alloys, while normal heat treatment improved it unobviously.