This study investigates the cyclic plastic deformation and microstructural evolution of hydrogen-charged 316L stainless steel. The results of low-cycle fatigue tests indicate that the samples with and without pre-charged hydrogen exhibit initial cyclic hardening and sequential cyclic softening at a low strain amplitude (≤0.5 %). However, a secondary cyclic hardening at a high strain amplitude (≥0.7 %) is observed near the end stage in both uncharged and hydrogen-charged samples. Microstructural evolutions characterized by electron backscattered diffraction and scanning transmission electron microscopy reveal the evident hydrogen-assisted dislocation nucleation and motion, which significantly enhances the accumulation of dislocation in the first cyclic hardening stage, resulting in fewer cycles to reach the first peak of responding stress amplitude. Moreover, the observed hydrogen-assisted twinning accelerates the formation of the secondary peak of stress amplitude. The hydrogen-assisted dislocation and twinning evolutions contribute to a reduction in the fatigue life of the steel.

中文翻译：

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预充氢316L不锈钢的循环变形及显微组织演化

本研究研究了充氢 316L 不锈钢的循环塑性变形和微观结构演变。低周疲劳试验结果表明，预充氢和未充氢的样品在低应变幅（≤0.5%）下均表现出初始循环硬化和后续循环软化。然而，在未充电和充氢样品中，在接近末期时观察到了高应变幅值 (≥0.7%) 的二次循环硬化。以电子背散射衍射和扫描透射电子显微镜为特征的微观结构演化揭示了明显的氢辅助位错成核和运动，显着增强了第一个循环硬化阶段位错的积累，从而减少了达到响应应力幅度第一个峰值的循环次数。此外，观察到的氢辅助孪晶加速了应力幅值第二峰的形成。氢辅助位错和孪晶演化导致钢的疲劳寿命缩短。