This study aimed to examine the stress–number of cycles (S–N) curve and fatigue limit of non-press-fitted parts to improve the sophistication of the design method of induction-hardened axles for medium-carbon steel high-speed railway cars. Macroscopic cracks were generated in the non-press-fitted parts of the axles by selecting appropriate fatigue test methods. Thus, the S–N curve was approximated, and the fatigue limit was obtained. The value of an index in the power-law expression of the S–N curve was 11, which was proposed to fatigue damage evaluation standard. Moreover, we constructed a prediction model for high-and very-high-cycle fatigue limits based on the local fatigue-limit approach and fatigue test results of cut-out specimens from several depth regions of induction-hardened axles. The fatigue limit predicted by the model agrees with the experimental high-cycle fatigue limit. The model estimated that the fatigue limit did not decrease in the very-high-cycle regime.

中文翻译：

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高速铁路车辆中碳钢全尺寸感应硬化车轴非压装部分的疲劳性能


本研究旨在检验非压装零件的应力-循环次数 （S-N） 曲线和疲劳极限，以提高中碳钢高速铁路车辆感应硬化车轴设计方法的复杂程度。通过选择合适的疲劳测试方法，在车轴的非压装部分产生宏观裂纹。因此，S-N 曲线被近似，并获得了疲劳极限。S-N 曲线的幂律表达式中 a 的指数值为 11，这是在疲劳损伤评估标准中提出的。此外，我们基于局部疲劳极限方法和感应硬化车轴多个深度区域的切割试样的疲劳测试结果，构建了高周和超高周疲劳极限的预测模型。模型预测的疲劳极限与实验高周疲劳极限一致。该模型估计，在极高循环状态下，疲劳极限并没有降低。