摘要
Abstract
There have been four cases of engine crankshafts fracture failure accidents in uses runnmg process, and the fractured parts were analyzed by means of chemical compositions analysis, metallographic examination, hardness test and fracture analysis. The results show that the crankshafts failed in high cycle and low stress bending fatigue fracture mode, and the main reason for the fracture was that there were many gathered distribution of machining marks on the crank surface near the transition position where stress concentration formed. In the users running process, under the action of overload or impact load formed because of vehicle condition, pavement and other complex factors, fatigue cracks initiated at the stress concentrated machining marks, and the cracks gradually propagated until the engine crankshafts fractured.关键词
发动机曲轴/机加工刀痕/高周低应力弯曲疲劳断裂Key words
engine crankshaft/machining mark/high cycle and low stress bending fatigue fracture分类
金属材料
