某型发动机曲轴在服役中发生断裂事故。因事故发生在该发动机服役中早期,且该机型属较成熟机型,分析其原因并找到解决办法,对避免其它品种发动机发生类似问题有着积极的现实意义。一、断裂曲轴的外观分析曲轴材料为40Cr,高频淬火、回火。其断裂位置靠近曲轴颈部,断裂纹呈抛物线状。观察曲轴断裂区域发现曲轴颈与曲臂位置表面粗糙度较高,光洁度差,裂纹周围有黑色斑点,用手触摸有凸凹感。曲轴断口处疲劳断裂特征突出。裂纹(疲劳 A type of engine crankshaft breaks in service. The accident occurred in the early service of the engine, and the model is more mature models, analyze the causes and find solutions, to avoid similar problems of other varieties of engines have a positive and practical significance. First, the appearance of broken crankshaft Crankshaft material for the 40Cr, high-frequency quenching and tempering. The fracture location close to the crankshaft neck, broken lines parabolic. Observation crankshaft fracture area crankshaft and crank arm found that the surface roughness is high, poor finish, cracks around the black spots, touch with a sense of relief. Fatigue fracture characteristics of crankshaft fracture prominent. Crack (fatigue