球化剂稀土含量对大断面球铁石墨组织及低温冲击韧性的影响  

Effect of Re content in nodulizer on graphite microstructure and low-temperature impact toughness of heavy section ductile cast iron

作　　者：李蒙[1] 

机构地区：[1]焦作大学机电工程学院,河南焦作454003

出　　处：《钢铁研究学报》2017年第11期919-925,共7页Journal of Iron and Steel Research

基　　金：河南省科技攻关计划资助项目(162102210352);焦作市科技计划资助项目(20151021064017)

摘　　要：选用3种具有不同Ce含量的球化剂FeSiMg6RE2、FeSiMg8RE3和FeSiMg8RE5对铁液进行盖包法处理,球化处理后浇注成180mm×180mm×200mm的球铁试块。通过室温拉伸、光学显微镜(OM)、扫描电子显微镜(SEM)、能谱分析仪(EDS)和低温冲击试验机等分析手段,研究了稀土元素Ce对大断面低温球铁的石墨组织、力学性能和低温冲击韧性的影响。结果表明:用稀土含量低的球化剂FeSiMg6RE2进行处理,试样的石墨组织细小均匀,石墨形态好,低温冲击韧性高,冲击功平均值约为14.5J;用稀土含量高的球化剂FeSiMg8RE3和FeSiMg8RE5分别进行处理,试样中出现了大面积碎块状石墨等变异组织,低温冲击韧性差,冲击功平均值分别约为6.5和5.1J。能谱分析结果表明:高稀土含量球化剂处理的球铁试样,石墨组织晶界上发生了稀土元素Ce的富集,其质量分数分别约为0.36%和0.42%,这是造成铸件中碎块状石墨等变异组织产生的根本原因,严重恶化了铸件的力学性能。Molten iron was treated in tundish-cover spheroidizing process by adopting three kinds of nodulizer（FeSiMg6 RE2,FeSiMg8 RE3 and FeSiMg8 RE5）with different Ce contents and ductile iron test blocks with the dimensions of 180 mm×180 mm×200 mm were poured.The influences of RE content in nodulizer on graphite microstructures and low-temperature impact toughness of heavy section ductile cast iron were investigated by room temperature tensile test,metallographic microscope（OM）,scanning electron microscope（SEM）,energy dispersive spectrometer（EDS）and impact testing machine.The results show that the sample can get fine graphite grain,better graphite morphology,and obtain high low-temperature impact toughness,and the average impact power is about 14.5 Jby nodularizing treatment adopting FeSiMg6 RE2;by adopting FeSi-Mg8 RE3 and FeSiMg8 RE5,a great deal of chunky graphite appears in the castings,the low-temperature impact toughness becomes bad,the average impact energy is only 6.5 and 5.1 J,respectively.And energy spectrum analysis shows that Ce is enriched at the grain boundary around the nodular graphite and the mass fraction is about 0.36 mass% and 0.42 mass%,respectively,which is the fundamental cause of the variation of the microstructure of the fragmented graphite,seriously deteriorating the mechanical properties of castings.

关 键 词：球化剂 稀土含量 大断面球铁 石墨组织 低温冲击韧性 

分 类 号：TG255[金属学及工艺—铸造]