【摘要】 通过组织观察、化学成分分析、碳氮共渗层深度及硬度测定，对20CrMnTi钢齿轮轴完成精加工后的轴向开裂原因进行分析。结果表明，齿轮轴的渗层组织主要为回火马氏体+少量残留奥氏体+二次碳化物，心部区域则由回火马氏体+铁素体组成，表层洛氏硬度为62.5 HRC,渗层有效硬化层深度约为0.73 mm,其化学成分、热处理工艺正常。齿轮轴的开裂出现在热处理前的锻造加工过程，不当的锻造工艺是出现开裂的主要原因。更多还原

【Abstract】 Axial cracking reasons of 20CrMnTi steel gear shaft after fine machining were analyzed by means of microstructure observation, chemical composition analysis, carbonitriding layer depth and hardness measurement. The results show that the carbonitrided layer of the gear shaft is primarily tempered martensite with a trace amount of retained austenite and proeutectoid cementite, while the core zone of the gear shaft is composed of tempered martensite and ferrite, with a surface Rockwell hardness of 62.5 HRC and an effective case depth of roughly 0.73 mm, The results further show that the raw materials and heat treatment procedure for the gear shaft are both normal. The gear shaft cracking appears in the forging process, with incorrect forging technique serving as the primary cause of the cracking.更多还原