摘要
某天然气发动机在进行可靠性验证时发生排气门断裂,采用形貌观察、化学成分分析和硬度检测等手段对其断裂原因进行了分析,并提出改进措施。结果表明,排气门材料的化学成分及硬度均符合GB/T 12773—2021要求;硬度法检测显示排气门最高实际工作温度为725~735℃,气门杆在高温作用下产生的氧化层向基体扩展并在气门杆表面形成微裂纹,高温导致层片状析出物沿晶析出进一步加快了微裂纹沿晶界扩展,逐渐发展成较深的裂纹,最终导致气门杆疲劳断裂。建议通过优化燃烧系统参数降低排气门的工作温度,或选用耐温性能更好的NCF 3015或Inconel 751材料,以使排气门满足工况要求。
During the reliability validation process of a specific natural gas engine,a fracture of the exhaust valve occurred.The fracture cause was analyzed by using methods such as morphology observation,chemical composition analysis and hardness testing,and improvement measures were proposed.The results indicate that the chemical composition and hardness of the exhaust valve material meet the requirements of GB/T 12773-2021.The hardness test shows that the maximum actual working temperature of the exhaust valve is 725-735℃.The oxide layer generated on the valve stem under high temperature extends to the substrate and forms microcracks on the surface of the valve stem.High temperature causes layered precipitates to precipitate along the grain boundary,further accelerating the propagation of microcracks along the grain boundary,and gradually developing into deeper cracks,ultimately leading to fatigue fracture of the valve stem.It is recommended that reducing the operating temperature of the exhaust valve through optimizing the combustion system parameters,or alternatively,selecting NCF 3015 or Inconel 751 materials with superior temperature resistance can ensure the exhaust valve meets the operational requirements.
作者
罗长增
曾笑笑
姚亚俊
徐得石
李旭聪
马宗桥
Luo Changzeng;Zeng Xiaoxiao;Yao Yajun;Xu Deshi;Li Xucong;Ma Zongqiao(Weichai Power Co.,Ltd.,Weifang Shandong 261061,China;State Key Laboratory of Engine and Powertrain System,Weifang Shandong 261061,China;College of Materials Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing Jiangsu 211106,China;School of Automotive Studies,Tongji University,Shanghai 200092,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2024年第12期301-305,共5页
Heat Treatment of Metals
基金
内燃机与动力系统全国重点实验室开放课题基金(skleps-sq-2023-080)。
关键词
天然气发动机
排气门
断裂
失效分析
natural gas engine
exhaust valve
fracture
failure analysis
