HR2钢动态损伤与层裂的微观机理

Micromechanism of the dynamic damage and spallation of HR2 steel

利用轻气炮加载和样品软回收技术,对HR2钢进行了试验,获得了软回收层裂样品。通过对软回收样品进行电子显微镜观察以及金相分析,将材料微观组织变化、破坏模式与相应的宏观力学破坏模式相比较,深入研究了这一材料的动态损伤与断裂机理。结果表明:在低速冲击下,HR2钢的变形是以孪生为主、滑移为辅的塑性变形,并未发生断裂;在高速冲击下,其变形是孪生和滑移的组合变形,断裂则是由沿晶界产生微孔洞、微裂纹并汇合形成大裂纹和少量穿晶断裂相混合引起的。

HR2 steel was shocked and the spall samples were obtained by using a light-gas gun and ＂sample soft-capture＂ technology. The samples were examined by electron microscope and metallographical analysis. By comparing the change of the microscopic structure and the mode of fracture with the corresponding fracture mode of macroscopic mechanics, the dynamic damage and failure mechanism of this material was studied. It shows that, at the low impact velocity （250 m/s）, twin deformation is primary and slipping deformation is secondary for the deformation of HR2 steel, also the material has no cracks; at the high impact velocity（500 m/s）twin arid slipping deformation are created together, and the microvoids appear along the grains boundary and they join with each other to become cracks, which make the material fracture.