铝合金在三种应力状态下的力学性能研究及断口分析

Study of mechanical performance and analysis of fracture surfaces of aluminum alloy in three patterns of stress state

通过对铝合金(6063)进行平板拉伸试验、带缺口的平板拉伸试验及纯剪切试验,研究了铝合金在三种应力下的力学性能.宏观试验结果发现:平板拉伸时的断裂应变大于带缺口拉伸时的断裂应变,而平板拉伸时的屈服应力及峰值应力小于带缺口拉伸时的屈服应力和峰值应力,剪切时材料的断裂剪应变远远大于平板拉伸时的断裂应变.三种应力状态下试样的断口也明显不同:缺口试样根部明显发生了颈缩现象,而且断面上存在着大量的韧窝;平板拉伸几乎没有发生颈缩现象,断面上的韧窝和剪切唇各占一定的比例;纯剪切试样断口上几乎以剪切唇为主.

The mechanical performance of aluminum alloy（6063）was investigated with its plate tension, notched plate tension and pure shear. It was found by macroscopic test that fracture stain of plate tension was larger than that of notched plate tension, yield stress and maximum stress of plate tension were less than those of notched plate tension, and fracture stain of pure shear was much larger than that of plate tension. The fracture surfaces of the sample in three stress states were obviously different as well： there were a lot of dimples on the fracture surfaces of notched specimen, and the plate at notch root was necked, plate tension almost did not result in necking, and there were proportional distribution of dimples and shear lips. There were mainly the shear lips on the fracture surface of pure shear specimen.