摘要
对断裂失效地铁弹簧进行了微观断口形貌、金相显微组织、残留奥氏体、显微硬度等方面的检测分析。结果显示,显微组织、晶粒度、残余奥氏体含量均正常,硬度偏低,断裂方式为疲劳断裂,且在断口上没有发现粗大的夹杂物。造成疲劳断裂的原因主要是回火温度偏高,导致弹簧强度不足,服役过程中,在交变载荷反复作用下,弹簧工作圈受到支撑圈的挤压,在工作圈表面产生压痕,进而发展成为疲劳源,经过一定时间的扩展后发生疲劳断裂。
The cause of cracking failure of the subway spring was analyzed by the analysis of micro fractographs, metallographic microstmcture, residual austenite and microhardness. The results show that microstmcture, grain size and residual austenite content are normal. The hardness is low. The fatigue fracture is the cracked way. And bulky occluded foreign substance on the fracture surface isn＇t found. The cause of cracking failure is the lack of strength of the spring, which is mainly due to the high tempering temperature. Under the alternating load repeatedly function on the spring in the process of service stress loading, spring ring world is being squeezed by support ring. And indentation is generated on the surface of the work ring. Then, a fountainhead of fatigue is formed. The crack expands, then breakdowns after a certain time.
出处
《热加工工艺》
CSCD
北大核心
2014年第6期224-225,212,共3页
Hot Working Technology
关键词
地铁弹簧
失效分析
疲劳断裂
subway spring
failure analysis
fatigue fracture
