高压扭转变形2A12铝合金组织性能演变与断裂行为

Microstructure and mechanical property evolutions of 2A12 aluminum alloy subjected to high pressure torsion and its fracture behavior

分别在室温(RT)、393 K、513 K和633 K开展扭转0.5-4 t的2A12铝合金的高压扭转(HPT)变形实验。通过对微观组织和室温力学性能进行观察、测量和统计,阐明了微观组织和力学性能随HPT工艺参数的变化规律。结合断口形貌和断口区域组织特征,对HPT变形试样的断裂行为进行了研究。结果表明:在RT-513 K区间,扭转0.5-4 t的HPT变形试样的抗拉强度(TS)均得到较大程度提升,其中在393 K、513 K扭转0.5 t的变形试样的伸长率(EL)同时得到较大程度改善,取得较好的强化与韧化效果。在RT扭转1 t的变形试样在不损失塑性的同时展示出本研究的最高TS值,TS值增至初始材料的156%,表现出穿晶断裂主导的混合断裂机制。

The high pressure torsion(HPT) deformation experiments of 2A12 aluminum alloy with 0.5-4 turns were carried out at RT, 393 K, 513 K and 633 K, respectively. Through the observation, measurement and statistics of the microstructure and mechanical properties at RT, the variations of microstructure and mechanical properties with HPT parameters were clarified. The fracture behaviors of HPT deformed specimens were studied by combining fracture morphology and microstructure characteristics near the fracture. The results show that the tensile strengths of HPT-(0.5-4 t) specimens have been greatly improved within the temperature range of RT-513K, among which the elongations of torsion deformed specimens with 0.5 t at 393 K and 513 K, respectively, have been greatly improved at the same time, showing a better strengthening and toughening effect. The torsion deformed specimen with 1 t at RT shows the maximum value of tensile strength in this study without loss of plasticity. Its tensile strength increases to 156% that of the initial material, showing a mixed fracture mechanism dominated by transgranular fracture.