The detection of the strain-induced martensitic transformation with the magnetic Barkhausen noise (MBN) was investigated in the high-cycle fatigue (HCF) of the AISI 304L stainless steel at different points of the surface of an hourglass-type specimen. Load-controlled fatigue tests with loads below and above the fatigue limit were performed. Each fatigue test was interrupted at certain numbers of cycles, prior to fracture, and MBN measurements were performed without applied loading. Comparing with the initial condition of the steel under study, no large changes in the MBN measurements were detected in the specimens subjected to loads near the fatigue limit, i.e., no $\alpha '$ -martensitic transformation was detected. In the specimen subjected to the greatest load, it was possible to detect an uncommon distribution of the MBN signals, which are correlated with the strain-induced $\alpha '$ -martensite and were verified with optical microscopy and X-ray diffraction (XRD). The results show that the MBN is a sensitive technique to detect the strain-induced $\alpha '$ -martensite in HCF tests, which can be used as an indirect parameter to show the fatigue damage of materials.

中文翻译：

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使用微磁无损检测评估 AISI 304L 不锈钢机械疲劳过程中产生的 α'-马氏体转变

在 AISI 304L 不锈钢的高周疲劳 (HCF) 中，在沙漏型试样表面的不同点处研究了用磁性巴克豪森噪声 (MBN) 检测应变诱发马氏体转变。进行载荷控制疲劳试验，载荷低于和高于疲劳极限。在断裂之前，每次疲劳试验都在一定的循环数下中断，并且在没有施加载荷的情况下进行 MBN 测量。与所研究钢的初始条件相比，在承受接近疲劳极限载荷的试样中未检测到 MBN 测量值的大变化，即没有 $\alpha '$ -检测到马氏体转变。在承受最大载荷的试样中，可以检测到 MBN 信号的不常见分布，这与应变引起的 $\alpha '$ -马氏体，并通过光学显微镜和 X 射线衍射 (XRD) 进行验证。结果表明，MBN 是一种检测应变诱导的灵敏技术。 $\alpha '$ HCF 试验中的 -马氏体，可用作间接参数来显示材料的疲劳损伤。