曲轴轴承座/连杆激光加工裂解槽的组织与胀断性能  

Organization and expansion breaking performance of fracture notch of crankshaft bearing and connecting rod by laser processing

作　　者：寇淑清[1] 王金伟[1] 郑祺峰[1] 杨慎华[1] 

机构地区：[1]吉林大学辊锻研究所,吉林长春130025

出　　处：《光学精密工程》2011年第4期768-774,共7页Optics and Precision Engineering

基　　金：国家自然科学基金资助项目(No.50375066); 高等学校博士学科点专项科研基金资助项目(No.20060183066)

摘　　要：采用Nd∶YAG脉冲激光对连杆所用材料C70S6钢和发动机曲轴轴承座常用材料灰铸铁进行了裂解槽加工,并在裂解设备上进行了胀断实验。采用工具显微镜、扫描电子显微镜和显微硬度仪等对比研究了裂解槽的几何形貌、裂解槽附近显微组织和显微硬度变化以及断口形貌,探讨了脉冲激光加工裂解槽的特性,揭示了脉冲激光加工韧/脆性材料裂解槽对胀断工艺的影响机制。结果表明:脉冲激光加工韧/脆性材料裂解槽的几何形貌、缺口效应均明显优于拉削加工和线切割加工,其中灰铸铁的缺口敏感性得到显著增强,在韧/脆性材料裂解槽附近均生成了易碎的马氏体,在槽的根部出现了微裂纹,组织明显细化;韧/脆性材料熔化区显微硬度约为820/850HV,相变硬化区约为860/550HV,显微硬度均高于基体,硬化效果显著;在C70S6钢槽根部区域未见韧性撕裂现象,韧/脆性材料断口都表现出脆性断裂特征,满足裂解工艺要求。Fracture splitting notches from C70S6 steel used in a connecting rod and from gray cast iron used in an engine crankcase main bearing bracket were processed by a YAG pulse laser,and the fracture splitting experiment was conducted in the fracture splitting device.The geometry appearances,microstructures,micro-hardness change as well as the fracture surface of fracture splitting notches were studied by a tool microscope,a scanning electronic microscope and a micro-hardness tester.Characteristics of fracture splitting notches processed by the pulse laser were discussed,and the influence of pulse laser processing fracture splitting notches from ductile/brittle materials on the expansion and breaking performance of the notchs was revealed.The results indicate that the geometry appearances and notch effects of the fracture splitting notches from ductile/brittle materials processed by the pulse laser are obviously superior to those of the broaching and linear cutting processing,and the gap sensitivity of gray cast iron has been strengthened greatly.The brittle martensite has been produced nearby the fracture splitting notches from ductile/brittle materials,and micro crack appears in the root of notch.The organization is obviously refined.The micro-hardnesses of melting zone and the solid phase transition zone of ductile/brittle materials approximately are 820/850 HV and 860/550 HV,respectively,which are higher than that of the substrate,and show a remarkable hardening effect.The ductile tearing phenomenon can not be seen in the C70S6 steel notch root zone.The ductile/brittle material fracture shows the brittle fracture characteristic,which satisfies the fracture splitting technological requirement.

关 键 词：韧/脆性材料 裂解槽 脉冲激光 显微组织 脆性断裂 

分 类 号：TG665[金属学及工艺—金属切削加工及机床]