Effect of chromium alloying and complex modification on structures and properties of white cast iron

Normal white cast iron and chromium alloying white cast iron were prepared using a melt-casting process,and their corresponding modified samples were cast after their melt were treated by a complex modification technique.By means of metallographic observation,carbide quantitative analysis and hardness measurement,effects of chromium alloying and complex modification on shape,distribution of carbides in white cast iron and properties were investigated.The results show that white cast iron has a network structure of(Fe,Cr)3C or(Fe,Cr)3C+(Cr,Fe)7C3 carbides when chromium content is low.By complexly modifying,the carbides become isolated and decentralized.With the increase of chromium content,all the carbides can change into(Cr,Fe)7C3 and exhibit chrysanthemum morphosis in a eutectic colony,with hexagon shape carbides appearing.Meanwhile the uniform distributed carbides without chrysanthemum morphosis can be obtained,but the hexagon shape carbides still exist.The Rockwell(HRC) hardness of the white cast iron is obviously increased by complexly modifying compared with the corresponding cast iron without modification.