镁/铝双金属复合管气压胀形-冷缩结合工艺研究

A new gas blow forming-cold contraction bonding process for Mg/Al composite tube forming was presented. The circumferential flow stress and elongation of AZ31 magnesium alloy and 7475 aluminum alloy were obtained by unidirectional hot tensile tests at 420, 440 and 460℃. On this basis, the initial and maximum air pressure required to deform the Al tube and Mg tube were calculated and the AZ31/7475 composite tube was manufactured at 460℃. The formed AZ31/7475 composite tube is closely combined with no metallurgical bonding. Due to the existence of eccentricity between the AZ31/7475 tubes and the die cavity, the wall thickness distribution of the cross section is not uniform. The residual contact stress between the outer tube and the inner tube was deduced, which includes the residual contact stress caused by the elastic recovery and that caused by the cold shrinkage of the two alloys. The residual contact stress of the composite tube was measured by the compression tests and the calculated value agrees well with the measured value, whose difference is about 19.2%.