The present paper was aimed at understanding the effect of lath martensite submicrostructure quenched at different austenitizing temperature on the crack propagation behaviour. Different techniques were used to characterize the details of microstructure and submicrostructure. In‐situ tensile tests with scanning electron microscope were performed to observe the propagation of the crack. The results illustrated that packet size and block size increase almost linearly with the increasing austenitizing temperature. However, austenitizing temperature has no significant effect on the size of laths. Both of the packet size and the block size match the Hall–Petch relationship well with a correlation coefficient of 0.99. In macro tensile tests and in‐situ tension, the deflection angle of crack encountered with prior austenite grain boundary is higher than 60°, while it is lower than 90° for packet boundary and 60° for block boundary. The deflection angle of crack is relevant to the interface energy of the encountered boundaries. The interface energy of prior austenite grain boundary is higher than that of packet boundary because of the component difference, while the interface energy of packet boundary is higher than that of block boundary because of larger misorientation.

中文翻译：

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板条马氏体亚显微组织对0.09C–1.7Mn–0.6Cr钢的原位拉伸对力学性能和裂纹扩展行为的影响

本文旨在了解在不同奥氏体化温度下淬火的板条马氏体亚显微组织对裂纹扩展行为的影响。使用了不同的技术来表征微观结构和亚微观结构的细节。用扫描电子显微镜进行了原位拉伸试验，以观察裂纹的扩展。结果表明，包大小和块大小几乎随奥氏体化温度的增加线性增加。但是，奥氏体化温度对板条尺寸没有显着影响。数据包大小和块大小均与Hall-Petch关系良好匹配，相关系数为0.99。在宏观拉伸测试和原位拉伸中，先前的奥氏体晶界遇到的裂纹的偏转角大于60°，而包形边界和块体边界的偏转角小于90°。裂纹的偏转角与遇到的边界的界面能有关。由于成分差异，原奥氏体晶界的界面能高于包晶界，而取向差较大，则包晶界的界面能高于块界的能。