风电用齿轮轴在最终热处理后的放置期间发生纵向开裂,本文对开裂齿轮轴的材料化学成分、力学性能、金相组织、裂纹及断口形貌进行了分析和检验。结果表明,裂纹从齿根下方的大尺寸非金属夹杂物处起裂,为残余应力作用下的氢致延迟开裂。拉应力区存在大尺寸非金属夹杂物以及热处理残余应力偏大是导致齿轮轴开裂的主要原因。 The gear shaft of wind turbine cracks longitudinally during the final heat treatment. In this paper, the chemical composition, mechanical properties, microstructure, crack and fracture morphology of the cracked gear shaft were analyzed and tested. The results show that the crack initiates from the large non-metallic inclusions under the root, which is caused by the residual stress. Tensile stress zone is the existence of large-size non-metallic inclusions and heat treatment residual stress is too large is the leading cause of gear shaft cracking.