【摘要】 通过成分分析、硬度测试、金相检验、宏观检验和断口分析等方法,对氢气压缩机螺栓断裂原因进行了分析。结果表明,螺栓断口基本与螺栓轴线垂直,断口全部位于螺栓与螺母旋合部分的第一扣螺纹根部,断口平齐,具有明显高应力疲劳断裂特征。在螺栓联接中,由于螺纹存在加工误差,使旋合的各扣螺纹不是同时全部接触,也不是同时承受载荷,因此,螺栓与螺母旋合的第一扣受载荷作用最大,且螺纹根部应力集中系数大,这是螺栓在交变载荷作用下首先产生裂纹源的外因。金相检验发现,材料中含有较多的夹杂物,呈点状分布,螺栓的组织不是综合机械性能良好的正常调质组织,降低了螺栓塑性韧性,这是螺栓裂纹扩展直至最终断裂的内因。更多还原

【Abstract】 Through chemical composition analysis, hardness test, metallographic examination, macroscopical test and fracture morphology analysis, the fracture cause of bolt was analyzed. The results show that fracture section of bolt is basically perpendicular to the axis of bolt, situated at the root of first screw in engaging part of bolt and nut and possesses the characteristic of clearly high stress fatigue fracture. In bolt coupling, because of machining error each engaging worm is not completely contacted with each other and beared load at the same time. So the load acted on first screw of bolt and nut is the biggest and stress concentrating coefficient at the root of bolt is bigger, which is the exterior cause formed cracking source under the action of fluctuating load. Metallographic examination shows that there are some inclusions appeared scattered distribution. Microstrcture is not normal QT structure of good mechanical property and decreases ductility and toughness, which is the inner cause made cracking spread and fracture finally.更多还原