超高强度钢靶板穿甲过程中层裂断口形貌分析

ANALYSIS OF LAYER SPLIT FRACTURE MORPHOLOGY OF ULTRA-HIGH STRENGTH STEEL TARGET UNDER PENETRATION

利用扫描电镜（SEM）对靶板层裂破坏崩落块断口形貌进行了分析,结果表明,后崩落块断口可分为三个区域,分别对应裂纹萌生与扩展的不同阶段.中心区域为波浪状拉伸韧窝,这里在熔融状态下受拉应力作用;平坦区为抛物线型韧窝,表明断裂是张开型和滑开型共同作用的过程;侧面为等轴韧窝,说明崩落块最终是被拉应力拉断的.因此层裂过程可分为:开坑挤压及前崩落块的剪切断裂阶段;干涉应力波引起的材料内部裂纹萌生阶段;后崩落块的张开与滑开共同作用的裂纹扩展和弹靶摩擦表面的熔化阶段以及最后的拉伸断裂阶段.整个过程为韧性断裂,这种韧性层裂破坏有时需要比冲塞破坏还要高的能量.

The fracture morphology of the fragments caused by the layer split of the ultra-high strength steel target under penetrating was investigated by scanning electron microscopy. The results show that the fracture morphologies of both front and back fragments are divided into different areas which correspond to the different stages of the initiation and propagation of crack. For back fragment, there are wave-like dimples in its central area, indicating that the tensile stress is responsible for the initiation of the crack. Outside the central area is the flat region consisting of parabola-shape dimples indicating the propagation of the crack resulted from the interaction of opening and sheraing. The dimples in the Ranks of both front and back fragments are all equal-axis ones suggesting that the fragments are finally broken by tensile stress. The process of the layer split is ductile rupture. The effect of layer split on protective ability of target was briefly discussed.