箱体主轴承座脉冲激光加工裂解槽实验研究

Experimental Study of Pulse Laser Processing Fracture Notch of Main Bearing Cap of Crankcase Bearing Bracket

采用Nd∶YAG脉冲激光对某发动机箱体主轴承座所用材料加工裂解槽。试验结果表明,激光热影响区组织得到细化,熔化区生成了细小的树枝状初晶和莱氏体,相变硬化区获得了隐针马氏体和残余奥氏体。X射线衍射(XRD)分析表明,熔化区碳浓度大于相变硬化区;裂解槽附近区域显微硬度均高于母材,硬化效果明显,熔化区显微硬度比相变硬化区高约260 HV;裂解槽硬化层随激光脉冲功率和脉冲宽度的增加而增大,随激光扫描速度的增加而减小,硬化层深度在0.232～0.625 mm之间;激光加工裂解槽为直缺口,灰铸铁的启裂和断裂效应明显。总结出激光功率、脉宽和加工速度等参数对裂解槽几何形貌的影响规律,并对工艺参数的选择提出了建议。

The fracture splitting notch is processed by Nd∶YAG pulse laser on the material of engine crankcase bearing bracket.The result shows that,the organization of laser heat-affected zone is refined,the melting zone produces the dendritic primary crystal and the ledeburite,the transformation hardening zone obtains hidden needle martensite and the retained austenite.The analysis of X-ray diffraction（XRD） indicates that the carbon density of the melting area is bigger than that of the transformation hardening zone.The micro hardness of the region nearby the fracture splitting notch is higher than that of the parent metal,the hardened effect is obvious and the micro hardness of the melting zone is approximately 260 HV higher than that of the transformation hardening zone.The hardening layer of the fracture splitting notch increases as the pulse power and the pulse width of laser increase,and reduces as the laser scanning speed increases.The depth of the hardening layer is between 0.232～0.625 mm.The fracture splitting notch that is processed by laser is the straight gap,which is a significant effect on the initiation fracture and fracture splitting of the gray iron.The influence law that laser power,pulse width,processing speed and other parameters on the morphology of fracture splitting notch is concluded,and the proposal to technological parameter′s choice is put forward.