驻车制动底板支撑座断裂分析  

Fracture analysis of parking brake bottom brackets

作　　者：吴双 黄平 谭江 罗敏 

机构地区：[1]重庆长安汽车股份有限公司工艺技术部,重庆401120

出　　处：《金属热处理》2016年第3期192-195,共4页Heat Treatment of Metals

摘　　要：驻车制动底板支撑座在路试中陆续发生几起断裂失效事故。通过宏观断口分析、金相组织分析、原材料化学成分及力学性能检测以及结合现场生产工艺等分析查找零件失效的原因,并提出了相应的改进措施。结果表明,支撑座断裂起裂点在外表面,无明显疲劳特征和塑性变形特征,属于脆性断裂。这是由于热镦工序感应加热温度过高,时间过长,出现魏氏组织,且后序工艺没有消除该组织造成。通过管控热镦感应加热工序及热镦后正火处理,可消除魏氏组织,经该工艺生产的支撑座在后续路试中均未再发生断裂现象。Several fracture failure accidents of parking brake bottom brackets occurred in succession during the road test of cars. Reasons of the fracture were studied by means of macroscopic fracture analysis,microstructure analysis,chemical composition analysis and mechanical properties testing of the raw materials and the scene of the production process survey. And corresponding improvement measures were proposed. The results show that the breaking of the supporting seat occurs from the outer surface,and no obvious fatigue characteristics and plastic deformation features observed. The brittle fracture is caused by over high induction heating temperature and over long soaking time,which leads to the appearance of widmanstatten. Widmanstatten can be avoided by regulating hot heading induction heating process and normalizing treatment after heading,therefore,no longer any fracture occurs in the following-up road test.

关 键 词：支撑座 脆性断裂 魏氏组织 正火 

分 类 号：TG115[金属学及工艺—物理冶金]