在发生表面剥落的GCr15钢滚动轴承的表面裂纹附近发现了一种针状相，利用SEM、透射Kikuchi衍射(TKD)和TEM等表征手段研究了这种针状相的微观特征，分析了这种针状相的形成机理及其与表面裂纹的相互作用。结果表明，在GCr15钢滚动轴承表面诱发的裂纹附近所形成的针状相是一种特殊的马氏体退化组织。这种针状相是因局部应力作用而形成的细长条状组织，其三维形貌为薄板状，内部存在微观孔洞和等轴状纳米晶。在滚动接触疲劳过程中，表面裂纹会优先沿针状相的微观孔洞扩展，使针状相的形成与表面裂纹的扩展相互促进，加速了轴承表面疲劳剥落的发生。

As a form of damage caused by rolling contact, rolling contact fatigue (RCF) can lead to early pitting and flaking on the raceway surface of bearings, which is frequently accompanied by the propagation and fracture of RCF cracks. When the RCF crack is initiated on the raceway surface, large amount of stress, e.g., fluid pressurization, may be exerted close to the crack faces, which can not only accelerate the crack growth and cause rapid failure of the bearing but also lead to local microstructural alternations in the bearing steel. In this study, a needle-like structure was observed close to the cracks with flaking occurring during RCF in a GCr15 rolling bearing. The microstructures of the needle-like structure were analyzed via SEM, transmission Kikuchi diffraction (TKD), and TEM to elucidate its microstructural constitutions and characteristics. Results illustrated that the needle-like structure is a thin plate in three dimension decorated with some microvoids and equiaxed ferrite nanocrystalline formed at the interfaces. The formation of the needle-like structure was attributed to the local stress exerted close to the crack surface during the RCF of the bearings. This structure may be a type of decayed microstructure of the martensitic matrix of the bearing steel. With the increasing RCF stress cycles, the microvoids in the needle-like structure may facilitate the initiation and propagation of surface cracks preferentially, thus accelerating the occurrence of surface fatigue flaking in the bearing.