The fracture in threaded portion of the second shaft of automobile gearbox was analyzed by means of chemical analysis?metallographic examination?macro and micro-scopic fractography .

• 变速箱第二轴在总装时发生批量断裂,断裂部位均在轴端螺纹收尾根部。采用化学成分分析、金相检验以及断口宏、微观分析等方法,对该轴的断裂原因进行分析。