Abstract We studied the combined and interactive effects of crystallographic orientation, strain amplitude, cycle number, stacking fault energy (SFE) and hydrogen doping on the microstructure evolution of polycrystalline high-manganese steels (HMnSs) under low-cycle fatigue (LCF). An integrated experimental approach combining digital image correlation (DIC), electron backscatter diffraction (EBSD) and electron channelling contrast imaging (ECCI) at interrupted cycles was performed in the same region of interest on the bulk shear samples, which enables us to systematically compare the dislocation patterns of grains with defined loading conditions at a much larger field of view and less artefacts compared to transmission electron microscopy (TEM). We found that Taylor factor (M) works well with describing the effect of crystallographic orientation, which was further proved by the crystal plasticity finite element method (CPFEM). In detail, grains with a medium M value (3.3–3.9) tend to form more complex dislocation pattern, which is defined as sensitive value. Generally, increasing strain amplitude and cycle number both promote the evolution of dislocation pattern while their efficiencies depend strongly on grain orientation. The promotion effect of SFE on dislocation evolution becomes obvious at larger strain amplitudes (>0.4%) and non-sensitive M value. Hydrogen can strongly assist the formation of e-martensite and reduce its critical resolved shear stress (CRSS), while it retards the evolution of dislocation pattern. The number of activated martensite variants in individual grain can be well predicted by its M value. With increasing strain amplitude, the fraction of e-martensite increases in a manner of thinner but denser plates.

中文翻译：

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取向、应变幅值、循环次数、层错能和氢掺杂对低周疲劳下多晶高锰钢显微组织演化的综合交互影响

摘要 我们研究了晶体取向、应变幅度、循环次数、层错能 (SFE) 和氢掺杂对低周疲劳 (LCF) 下多晶高锰钢 (HMnSs) 微观结构演变的综合和交互影响。在体剪切样品的同一感兴趣区域中进行了结合数字图像相关 (DIC)、电子背散射衍射 (EBSD) 和电子通道对比成像 (ECCI) 的综合实验方法，这使我们能够系统地比较与透射电子显微镜 (TEM) 相比，在更大的视野和更少的伪影下，具有确定的加载条件的晶粒的位错模式。我们发现泰勒因子 (M) 可以很好地描述晶体取向的影响，晶体塑性有限元法（CPFEM）进一步证明了这一点。具体而言，中等 M 值（3.3-3.9）的晶粒倾向于形成更复杂的位错模式，这被定义为敏感值。通常，增加应变幅度和循环次数都会促进位错模式的演变，而它们的效率在很大程度上取决于晶粒取向。SFE 对位错演化的促进作用在较大的应变幅度 (>0.4%) 和不敏感的 M 值下变得明显。氢可以强烈地协助马氏体的形成并降低其临界分辨剪切应力 (CRSS)，同时它会延缓位错模式的演变。单个晶粒中活化马氏体变体的数量可以通过其 M 值很好地预测。随着应变幅值的增加，