Study of duplex ageing treatment of AZ80 magnesium alloy after deformation at room temperature

Duplex ageing treatment was performed on AZ80 magnesium alloy deformed at room temperature. This study focus on the ageing treatment process on the deformed alloys, and the table of L-16(4(5)) of orthogonal design was adopted in the experiment. The influence of ageing treatment process on the hardness and microstructure were analyzed and discussed. The experimental results show that the hardness increased with increase of deformation ratio, which is up to the peak value at 30%. The order of effects on hardness is the time of second-stage ageing treatment, the temperature of second-stage ageing treatment, the time of first-stage ageing treatment, the temperature of first-stage ageing treatment in turn. The optimal heat treatment process were obtained, which were consisted of solution treated at 420 degrees C for 10h, deformation with 30% ratio, first-stage aged at 140 degrees C for 12h, followed by second-stage aged at 180 degrees C for 16h. The sample of AZ80 magnesium alloy treated under the optimal process has homogeneous and fine grains and comprehensive property.