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对不同高径比H/D的7A60铝合金坯料进行高压扭转实验,借助于EBSD技术分析了变形7A60铝合金微观组织(晶界取向差、晶粒取向)演变规律,同时对变形7A60铝合金进行拉伸实验和断口扫描,分析7A60铝合金的抗拉强度、断裂方式和断裂机理。研究结果表明:高压扭转变形后7A60铝合金晶粒发生了明显破碎细化,当高径比H/D为0.25时,晶粒取向沿<001>、<101>方向;当进一步减小高径比H/D时,在三叉晶界处出现了细小的动态再结晶晶粒,取向角在2°≤θ≤5°范围内的小角度晶界比例较大,同一晶粒内部出现了颜色渐变区,大部分晶粒取向沿<111>方向;高压扭转变形后7A60铝合金抗拉强度明显提高,最高抗拉强度达到了751 MPa,提升幅度达到了20.74%,在强度得到大幅提高的同时伸长率也得到了较好的保持,最高伸长率为14%;高压扭转变形后7A60铝合金断裂方式为塑性断裂,断裂机理属于微孔连接断裂。
High-pressure torsion experiments were carried out on 7A60 aluminum alloy billets with different height-diameter ratios H / D. The evolution of microstructures (grain boundary orientation and grain orientation) of the deformed 7A60 aluminum alloy was analyzed by EBSD technique. Tensile test and fracture scanning to analyze the tensile strength, fracture mode and fracture mechanism of 7A60 aluminum alloy. The results show that the grain size of 7A60 aluminum alloy is significantly broken and refined after high-pressure torsional deformation. When the aspect ratio H / D is 0.25, the grain orientation is along the direction of <001> and <101> At H / D, fine dynamic recrystallization grains appear at the trigeminal grain boundaries with a large proportion of small-angle grain boundaries with the orientation angle within the range of 2 ° ≤θ≤5 ° and a gradual color change within the same grain The tensile strength of 7A60 aluminum alloy is obviously increased after high-voltage torsional deformation, the highest tensile strength reached 751 MPa, the lifting amplitude reached 20.74%, while the tensile strength was greatly increased at the same time The length of the aluminum alloy is also well maintained, the maximum elongation is 14%. The fracture mode of 7A60 aluminum alloy is plastic fracture after high-pressure torsional deformation, and the fracture mechanism belongs to micropore fracture.