Abstract Fine Granular Area (FGA) and White Etching Cracks (WEC) are two types of fatigue damage phenomena which are characterised by the development of cracks accompanied by a local microstructural transformation. The resulting microstructures share many properties, chiefly a strong reduction in grain size. In this study, the thickness of the transformed zones along the crack formed during FGA and WEC experiments is investigated. It is shown that in WEC, similar to earlier results on the FGA, the size of the transformed zones increases with increasing crack length. For further analysis of the more complex WEC case, an approach is presented that uses the results of a critical plane analysis for the calculation of key figures in fracture mechanics. The results are shown to be very similar to those of the FGA. Drawing on these and earlier results, it is proposed that a common mechanism of WEC and FGA formation exists. In addition, some important differences of the two phenomena are explained within the framework of the common mechanism.

中文翻译：

---

AISI 52100轴承钢细颗粒区及白色蚀刻裂纹形成机理

摘要 细颗粒区（FGA）和白蚀裂纹（WEC）是两种疲劳损伤现象，其特征是裂纹的发展伴随着局部的微观结构转变。由此产生的微观结构具有许多特性，主要是晶粒尺寸的显着减小。在这项研究中，研究了沿 FGA 和 WEC 实验期间形成的裂纹的转变区的厚度。结果表明，在 WEC 中，类似于早期 FGA 的结果，转变区域的大小随着裂纹长度的增加而增加。为了进一步分析更复杂的 WEC 情况，提出了一种方法，该方法使用临界平面分析的结果来计算断裂力学中的关键数据。结果显示与 FGA 的结果非常相似。借鉴这些和早期的结果，提出WEC和FGA形成的共同机制存在。此外，在共同机制的框架内解释了这两种现象的一些重要差异。