汽车排气歧管用高镍球墨铸铁组织与抗热疲劳性能的研究  

Study on Microstructure and Thermal Fatigue Resistance of Ductile Ni-resist Cast Iron for Exhaust Manifold

作　　者：刘华莉[1] 

机构地区：[1]郑州科技学院车辆与交通工程系

出　　处：《热加工工艺》2018年第1期139-142,共4页Hot Working Technology

基　　金：河南省高等学校青年骨干教师资助计划项目(2013GGJS-181)

摘　　要：为了满足汽车排气歧管工作环境要求,设计并熔炼了一种高镍球墨铸铁新型材料。通过微观组织观察、热疲劳性能测试、膨胀系数测试、差热分析等方法,研究其铸态组织、抗热疲劳性能及合理的工作温度。结果表明：高镍球墨铸铁显微组织主要由奥氏体基体、石墨、金属间化物FeNi3组成,石墨尺寸10～25μm,以球状为主。随着热循环次数的增加,组织中球状石墨因收缩导致与基体间出现微裂纹,表面石墨因高温而氧化、消失,形成沟蚀,都会形成显微热裂纹源。高镍球墨铸铁材料合理的工作温度为950℃以下。In order to meet the work environment requirements of automobile exhaust manifold, a new type of high nickel ductile iron material was designed and melted. The as cast microstructure, thermal fatigue resistance and reasonable working temperature were studied by observation of microstructure and thermal fatigue performance test, test for expansion coefficient, differential thermal analysis and other methods. The results show that ductile Ni-resist cast iron microstructure is mainly composed of austenitic matrix, graphite, intermetallic compound FeNi3, the graphite size is 10-25μm, which is mainly spherality. With the increase of the number of thermal cycles, spheroidal graphite due to shrinkage leads to microcrack between matrix, surface graphite is oxidized by high temperature and disappears resulting in liner erosion which forms the thermal micro-crack source. Reasonable working temperature of ductile Ni-resist cast iron material is below 950℃.

关 键 词：高镍球墨铸铁 排气歧管 抗热疲劳性能 

分 类 号：TG255[金属学及工艺—铸造] TG143.5[一般工业技术—材料科学与工程]