Microstructure and Mechanical Properties of AA6061/AZ31B/AA6061 Composite Plates Fabricated by Vertical Explosive Welding and Subsequent Hot Rolling

In this study, three-ply Al/Mg/Al composite plates were successfully achieved by vertical explosive welding (EXW) method. After EXW, the sound joints were obtained. Then thin three-ply Al/Mg/Al EXWed composite plates with the thickness of 1.78 mm were achieved by hot rolling. The influence of annealing on the interface microstructures and mechanical properties of the thin composite plates was investigated. The results indicated that different morphology with big waveform and mini waveform was present in the explosively bonded interface. The interface shear strength was 91MPa for big waveform side and 92Mpa for mini waveform side. The rolled sample without annealing possessed the high ultimate tensile strength (UTS) value of 235Mpa and elongation of 8.5%. The equiaxed and homogeneous grain morphology of magnesium alloys in the thin three-ply Al/Mg/Al composite plates could be induced by annealing 300°C for 1 h. This contributed to the considerable increase of elongation by 18.5%.

本研究采用垂直爆炸焊接（Explosive Welding, EXW）技术成功制备了三层Al/Mg/Al复合板。爆炸焊接完成后，获得了结合质量优异的接头；随后通过热轧工艺制备得到厚度为1.78 mm的超薄三层Al/Mg/Al爆炸焊接复合板。本研究探究了退火工艺对该超薄复合板界面微观组织与力学性能的影响。结果表明，爆炸焊接界面存在两种不同的波形形貌：大波形与小波形；大波形侧界面的剪切强度为91 MPa，小波形侧则为92 MPa。未退火的热轧试样具备较高的抗拉强度极限（Ultimate Tensile Strength, UTS），达235 MPa，断后伸长率为8.5%。在300 ℃退火1 h后，可使该三层Al/Mg/Al超薄复合板中的镁合金晶粒呈现等轴均匀的形貌，这使得断后伸长率显著提升了18.5%。