Evaluation of the boundary strength of ferrous martensite through a micromechanical test

我们研究了马氏体的块边界和亚块边界强度，通过微观力学测试来评估。子块边界对马氏体宏观强度的影响很小。而块体边界的存在则大大提高了试件的强度。此外，块体边界在荷载-位移曲线上引起锯齿状流动和荷载下降。载荷下降和锯齿状流动归因于位错堆积和随后的位错在块体边界上的传播。在变形后试样的显微组织观察中，我们发现块边界对位错的运动有明显的限制，而子块边界对位错的运动没有明显的限制。结果表明，块状晶界是提高马氏体强度最有效的晶界。

We investigated the block boundary and sub-block boundary strengths of martensite evaluated through a micromechanical test. The sub-block boundaries contribute very little to the macroscopic strength of martensite. In contrast, the existence of a block boundary in the specimen greatly increased the strength. In addition, the block boundary induced a serrated flow and load drop in the load-displacement curve. The load drop and serrated flow were attributed to dislocation pile-up and subsequent propagation of dislocations across the block boundary. In a microstructural observation of specimens after deformation, we found that a block boundary significantly restricts the motion of dislocations, while sub-block boundary does not. We concluded that the block boundary is the most effective grain boundary for strength in martensite.