Effect of geometric lath orientation on fatigue crack propagation via out-of-plane dislocation glide in martensitic steel
Effect of geometric lath orientation on fatigue crack propagation via out-of-plane dislocation glide in martensitic steel
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DOI：
10.1016/j.scriptamat.2021.114045
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发表时间：
2021-10
影响因子：
6
通讯作者：
Shohei Ueki;Y. Mine;Xinyu Lu;Y. Chiu;P. Bowen;K. Takashima
中科院分区：
文献类型：
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作者：
Shohei Ueki;Y. Mine;Xinyu Lu;Y. Chiu;P. Bowen;K. Takashima
使用三维电子背散射衍射 (3D-EBSD) 技术检查中碳钢马氏体板条中疲劳裂纹尖端前方的应变积累。本研究的目的是解释由于平面外滑移的激活而导致的裂纹扩展机制，其伯格斯矢量不具有裂纹扩展方向的分量，从而表现出对疲劳裂纹扩展的高抵抗力。 3D-EBSD 分析显示晶体中几乎没有错误取向，同时粗板条中的疲劳裂纹扩展有利于位错沿其纵向滑移。这表明这些板条有助于应变调节。相反，应变优先累积在不利于纵向滑移的粗板条中，从而促进裂纹扩展。这些表明马氏体板条的几何各向异性和分布决定了马氏体碳钢的疲劳裂纹扩展阻力。
Strain accumulation ahead of the fatigue crack tip in the martensite lath of a medium-carbon steel was examined using a three-dimensional electron backscatter diffraction (3D-EBSD) technique. The objective of this study is to explain the crack propagation mechanism due to the activation of out-of-plane slips with their Burgers vectors having no component of the crack growth direction, which exhibits high resistance to fatigue crack growth. The 3D-EBSD analysis revealed little misorientation in the crystal, concurrent with the fatigue crack propagation in the coarse laths oriented favourably for dislocation glide in their longitudinal directions. This suggests that these laths contributed to strain accommodation. In contrast, strain preferentially accumulated in the coarse laths oriented unfavorably for the longitudinal slip, promoting crack propagation. These indicate that the geometrical anisotropy and distribution of martensite laths dominate the fatigue crack propagation resistance in martensitic carbon steel.