Abstract High and very high cycle fatigue (VHCF) tests were performed with 17-4PH stainless steel under constant amplitude (CA) and variable amplitude (VA) loading at load ratios of −1 and 0.05. Stepwise (duplex) S-N curves were determined with failure from surface inclusions above the transition stress amplitude, σtr, and from the interior below σtr. Similar σtr for CA and VA loading were found. VA failure occurred at Miner damage sums between 0.1 and 0.9 (surface failure) and 0.2 and 2.2 (internal failure). Omission of stress amplitudes less than 60% of the maximum amplitude is allowable for VA studies in the VHCF regime.

中文翻译：

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具有阶梯式SN曲线的17-4PH钢的变幅甚高周疲劳

摘要 在恒幅 (CA) 和变幅 (VA) 载荷下，以 -1 和 0.05 的载荷比对 17-4PH 不锈钢进行了高周疲劳和甚高周疲劳 (VHCF) 试验。阶梯式（双相）SN 曲线是由表面夹杂物高于过渡应力幅度 σtr 和内部低于 σtr 的破坏确定的。发现了 CA 和 VA 加载的类似 σtr。VA 故障发生在 Miner 损坏总和介于 0.1 和 0.9（表面故障）和 0.2 和 2.2（内部故障）之间。对于 VHCF 制度中的 VA 研究，允许省略小于最大振幅 60% 的应力振幅。