球墨铸铁电弧堆焊热影响区组织演变规律研究  

Study on Microstructure Evolution of Heat Affected Zone of Ductile Iron During Arc Surfacing

作　　者：曾大新[1] 何中璞 史秋月[1] ZENG Da-xin;HE Zhong-pu;SHI Qiu-yue(Hubei University of Automotive Technology,Shiyan 442002,Hubei,China)

机构地区：[1]湖北汽车工业学院,湖北十堰442002

出　　处：《铸造》2022年第10期1209-1215,共7页Foundry

摘　　要：用OM、SEM和EDS观测球墨铸铁电弧堆焊Fe基合金的热影响区微观组织及元素偏析,对微观组织的演变过程进行研究。结果表明,球墨铸铁在堆焊热循环下组织发生变化的热影响区域可分成部分熔化区和奥氏体化区,部分熔化区是快速加热条件下石墨溶解到铁基体的碳扩散不均匀而发生非平衡熔化而形成的,不需要固相线与液相线温度区间存在,熔化发生在石墨球周围,铁液凝固时在石墨球周围形成一层奥氏体和一层莱氏体的双层壳型组织形态。奥氏体化区在加热时珠光体和石墨球周围的铁素体首先发生奥氏体转变,该奥氏体在随后冷却时转变成为马氏体;离石墨球远处的铁素体加热时转变成碳浓度较低的奥氏体或保持不变,低碳奥氏体冷却时再转变成为铁素体,铁素体球墨铸铁的奥氏体化区形成了石墨球周围为马氏体,余为铁素体的组织。The microstructure and element segregation in the heat affected zone(HAZ)of ductile iron surfaced with Fe-based alloy by arc welding were observed by OM,SEM and EDS,and the microstructure evolution was investigated.The results showed that the area of the microstructure change of ductile iron under the welding thermal cycle could be divided into partial melted zone(PMZ)and austenitized zone(AZ).The formation of PMZ was due to non-equilibrium melting under the condition of rapid heating that led to an inhomogeneous distribution of carbon from graphite dissolving in iron matrix,which could be produced when there was no solidus and liquidus temperature range,the melting of the iron occurred around the graphite,and a doublelayer shell structure of austenite and ledeburite was formed around the graphite during solidification of melted iron.In the AZ,pearlite and ferrite at periphery of graphite first transformed to austenite when heating,this austenite transformed to martensite on subsequent cooling.The ferrite far from the graphite was transformed to low carbon austenite or remained unchanged during heating,low carbon austenite then transformed to ferrite on cooling.In the AZ of ferrite ductile iron,a structure consisting of martensite around the graphite and remained ferrite was formed.

关 键 词：球墨铸铁 电弧堆焊 热影响区 微观组织 

分 类 号：TG255[金属学及工艺—铸造]