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为了深入了解镁合金绝热剪切带与裂纹的关系,进而揭示镁合金在高速冲击载荷作用下局部变形绝热剪切的组织演变规律,采用分离式Hopkinson压杆对AZ31镁合金的帽状式样进行冲击压缩实验,而后利用光学显微镜,扫描电镜和维氏硬度计分别对冲击后的AZ31试样进行分析。结果表明,绝热剪切带形成于最大剪应力方向,随着冲击载荷的不断增加,沿着切应力方向上的微孔洞和微裂纹不断长大,直至彼此相互连接成裂纹,最终导致材料的断裂。经对剪切带及周围组织维氏硬度的测量发现,剪切带内细小晶粒区的硬度明显高于周围组织。
In order to understand the relationship between the adiabatic shear band and the crack of magnesium alloy, and then reveal the microstructure evolution of the adiabatic shear of the magnesium alloy subjected to local impact under high-speed impact load, the split Hopkinson pressure bar was used to impact the cap pattern of AZ31 magnesium alloy Compression experiments were carried out, and then the impact of AZ31 samples were analyzed by optical microscope, scanning electron microscope and Vickers hardness tester respectively. The results show that the adiabatic shear band is formed in the direction of the maximum shear stress. With the increase of impact load, the microholes and microcracks in the direction of shear stress continue to grow until they are connected to each other into a crack, fracture. Measurement of Vickers hardness of the shear band and the surrounding tissue revealed that the hardness of the fine crystal grain region in the shear band was significantly higher than that of the surrounding tissue.