传动轴断裂原因分析

Analysis on Cause of Transmission Shaft Fracturing

某公司一45Cr钢传动轴仅仅使用了50 h即断裂。对断裂的传动轴进行了宏观检查、表面硬度检测、金相检验、化学成分分析和断口分析。结果表明:传动轴的表面硬度远低于要求值,显微组织为珠光体和铁素体,也不符合要求,说明该传动轴未经过调质处理,因此其力学性能差;此外,传动轴表面粗糙,有机加工痕迹。不良的力学性能和粗糙的表面导致传动轴过早疲劳断裂。

A transmission shaft made of 45Cr steel broke at the time when it was used for as little as 50 h in one company.The broken transmission shaft was subjected to macro-check,surface hardness measurements,metallographic examination,chemical composition analysis,and fracture testing.The results indicated that the transmission shaft exhibited surface hardness considerably lower than required values and undesirable microstructure consisting of pearlite and ferrite,which showed it did not be quenched and temped,thereby had poor mechanical properties.In addition,the transmission shaft showed rough surface with machining marks.The poor mechanical properties and the rough surface resulted in premature fatigue failure of the transmission shaft.