摘要
目的研究18CrNi4WA钢渗碳针阀体开裂失效原因。方法通过化学成分分析、断口扫描分析、金相组织分析、能谱分析等测试手段,对18CrNi4WA钢渗碳针阀体的断裂模式及失效原因进行分析。结果针阀体失效件原始材料符合针阀体制造要求,但渗碳淬火温度过高,未得到最优的渗碳层组织,燃油中存在的硫元素导致喷油孔位置产生严重腐蚀,燃油局部压力的变化导致针阀体表面产生空蚀损伤,裂纹起始于喷油孔圆周面,自裂纹源向外发散呈月牙状,为典型疲劳断裂特征。结论腐蚀与空蚀损伤的协同作用加快裂纹的萌生,使针阀体在热疲劳及机械振动等交变载荷的作用下产生疲劳开裂,使用寿命大为降低。
Objective To investigate cracking failure reasons of the carburized injector valve made of 18CrNi4WA steel.Methods The fracture modes and failure reasons of the injector valve were analyzed by means of chemical composition analysis,SEM analysis,metallographic examination and energy spectrum analysis.Results The original material of the needle valve was in conformity with the manufacturing requirement.But due to the high carburizing quenching temperature,the best carburized layer structure was not obtained.The sulfur element in fuel caused serious corrosion of injection holes.Changes of the local pressure in the fuel oil caused cavitation damage on the surface of the needle valve body.The crack began at the circumferential surface of the injection hole and radiated from the crack source to the crescent shape.It was called as typical fatigue fracture.Conclusion Synergistic effects of the corrosion and cavitation damage promote crack initiation and produces fatigue cracking under the action of the thermal-mechanics alternate fatigue load.The service life of the injector valve was greatly reduced.
作者
吴帅
王长鹏
苏艳
陈喜栋
张凯
赵丽旸
WU Shuai;WANG Chang-peng;SU Yan;CHEN Xi-dong;ZHANG Kai;ZHAO Li-yang(Southwest Research Institute of Technology and Engineering,Chongqing 400039,China;China institute of marine technology and economy,Beijing 100081,China)
出处
《装备环境工程》
CAS
2018年第7期75-79,共5页
Equipment Environmental Engineering
