摘要
对断裂的汽车张紧轮紧固螺栓的显微组织、化学成分、硬度以及断口的宏、微观特征进行了综合分析,找出其断裂的原因。结果表明:螺栓在搓丝加工过程中挤压量过大,使螺纹尖端产生较多微裂纹,同时螺纹根部也存在一些加工缺陷,并在之后的热处理过程中进一步扩展;在使用过程中,微裂纹和加工缺陷处产生应力集中,使螺栓材料的疲劳强度降低,裂纹源的过早形成最终导致了螺栓发生疲劳断裂而失效。
A comprehensive analysis of microstructure, chemical composition, hardness, macro and micro features was carried out to study the fracture reasons of auto tensioner fastening bolts. The results show that excessive extrusion in the thread rolling process led to a lot of micro-cracks in the thread tip and processing defects at the root of threads respectively, which further expanded in the later heat treatment process, and caused the stress concentration and thus reduced the fatigue strength of the material when the bolts were in use. The premature formation of crack source led to fatigue fracture and failure of the bolts.
出处
《机械工程材料》
CAS
CSCD
北大核心
2015年第9期103-105,110,共4页
Materials For Mechanical Engineering
基金
中央高校基本科研业务费专项资金资助(A0920502051413-2)
关键词
螺栓
微裂纹
缺陷
疲劳断裂
bolt
micro-crack
defect
fatigue fracture
