Rolled steel plates and sections are often applied in structures in such a way that the principal load direction corresponds with the rolling direction. Examples are beams, arches, or pylons of bridges, supporting beams of ship decks, and the main elements of crane structures. However, some types of structure are subjected to a multiaxial stress state or are loaded with the main load direction perpendicular to rolling. The orientation may influence the mechanical properties. This paper studies the influence of anisotropy observed in the microstructure of rolled C–Mn steels on the tensile properties, Charpy impact values and particularly the fatigue crack growth rates. The influence of anisotropy is determined through tests performed at different orientations with respect to the rolling direction, namely, L‐T, T‐L and T‐S orientations. Samples were taken from structures that were constructed between 25 and 50 years ago from steel grades Fe510C or St52.3 (modern equivalences S355J2 or S355N). The orientation appears to have a statistically relevant influence on Charpy impact value and fatigue crack growth rate. The anisotropy ratio, defined as the ratio between the mechanical property in a certain orientation with that of the L‐T orientation, ranged between 0.30 and 0.53 for Charpy impact values. The anisotropy ratios appear correlated with the absolute Charpy value, with a correlation coefficient of ρ = −0.8. The anisotropy ratios of the crack growth in T‐L and T‐S orientations were 1.19 and 0.43, respectively. Anisotropy ratios for crack growth appear uncorrelated with anisotropy ratios for Charpy impact. The observed anisotropy may partially explain the difference between uniaxial and multiaxial fatigue crack growth as determined by others.

中文翻译：

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材料各向异性对现有结构碳锰钢疲劳裂纹扩展的影响

轧制钢板和型材通常以主载荷方向与轧制方向一致的方式应用于结构中。例如，桥梁的梁，拱或塔，船甲板的支撑梁以及起重机结构的主要元件。然而，某些类型的结构处于多轴应力状态或以垂直于轧制的主载荷方向载荷。方向可能会影响机械性能。本文研究了在轧制的C-Mn钢的显微组织中观察到的各向异性对拉伸性能，夏比冲击值以及疲劳裂纹扩展速率的影响。各向异性的影响是通过在相对于轧制方向的不同方向（即L-T，T-L和T-S方向）上进行的测试确定的。样品取自25到50年前的Fe510C或St52.3钢（现代等效品S355J2或S355N）。取向似乎对夏比冲击值和疲劳裂纹增长率具有统计学上的相关影响。夏比冲击值的各向异性比（定义为某一方向的机械性能与L‐T方向的机械性能之比）介于0.30至0.53之间。各向异性比似乎与绝对夏比值相关，相关系数为 夏比冲击值的各向异性比（定义为某一方向的机械性能与L‐T方向的机械性能之比）介于0.30至0.53之间。各向异性比似乎与绝对夏比值相关，相关系数为 夏比冲击值的各向异性比（定义为某一方向的机械性能与L‐T方向的机械性能之比）介于0.30至0.53之间。各向异性比似乎与绝对夏比值相关，相关系数为ρ＝ -0.8。T‐L和T‐S方向裂纹扩展的各向异性比分别为1.19和0.43。裂纹扩展的各向异性比似乎与夏比冲击的各向异性比不相关。观察到的各向异性可能部分解释了由其他人确定的单轴和多轴疲劳裂纹扩展之间的差异。