ABSTRACT The influence of low-temperature gaseous carburisation on notch fatigue behaviour of 316L steel under cyclic axial loading was investigated. After carburisation, the carburised case was well distributed at the surface region and was not influenced by the notch geometry. Low-temperature carburisation considerably enhanced the notch fatigue performance, which led to 32% and 44% increase in the endurance limits for the specimens with stress concentration factors K t = 1.91 and 3.91, respectively. The notch sensitivity of 316L steel reduced after carburisation. Irrespective of the applied stress amplitude, the fatigue crack nucleation sites were always at the notch root surface for the untreated specimens. For the carburised specimens, fatigue cracks nucleation changed from surface at high-level stress to subsurface at low-level stress.

中文翻译：

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低温气态渗碳316L奥氏体不锈钢缺口疲劳行为

摘要 研究了低温气体渗碳对 316L 钢在循环轴向载荷下缺口疲劳行为的影响。渗碳后，渗碳情况在表面区域分布良好，不受凹槽几何形状的影响。低温渗碳显着提高了缺口疲劳性能，这导致应力集中系数 K t = 1.91 和 3.91 的试样的耐久极限分别增加了 32% 和 44%。316L钢渗碳后缺口敏感性降低。无论施加的应力幅度如何，未处理试样的疲劳裂纹形核位置总是在缺口根部表面。对于渗碳试样，疲劳裂纹的形核从高应力下的表面转变为低应力下的亚表面。