固溶处理对7B52铝合金板材力学性能和断裂行为的影响

摘要

The effect of solution treatment on mechanical properties and fracture behavior of 7B52 aluminum alloy plate were investigated in this work. The mechanical properties were investigated by tensile test and Charpy impact test, while scanning electron microscopy (SEM) and Electron Back-Scattering Diffraction (EBSD) were used to characterize average grain sizes and fraction of recrystallized grain. The results show that the degree of solid solution and recrystallization increase with the solution temperature increases. When the temperature exceeds 480 ℃, the mechanical properties of 7B52 alloy is weakened. When the solution treatment at 475 ℃ and the time exceeds 1 h, the microstructure changes very little with the time prolonges. The fracture mechanism of 7B52 aluminum alloy is transgranular fracture and intergranular fracture coexist mixed fracture, and recrystallized grain boundary is the inter-granular crack behavior propagation path, and the transgranular fracture behavior is significantly affected by Fe/Mn rich undissolved second phase.%采用室温拉伸实验和夏比冲击实验测试力学性能,采用扫描电子显微镜(SEM)和电子背散射衍射(EBSD)分析平均晶粒尺寸、再结晶晶界比例及断口形貌等显微组织特征,通过分析显微组织与断裂行为之间的关系,研究固溶处理对7B52铝合金板材力学性能和断裂行为的影响.结果表明:随着固溶温度的升高,合金组织中Mg(Zn,Cu,Al)2四元相回溶速度、再结晶比例增加,当温度超过480℃时,对合金力学性能不利;475℃固溶1h后,随着时间的延长,显微组织变化不明显.7B52合金断裂机制为穿晶断裂和沿晶断裂并存的混合型断裂,沿晶裂纹沿着再结晶晶界扩展,富Fe/Mn的难溶第二相是发生穿晶断裂的主要原因.