Abstract: Effect of strong carbide elements and RE element on the quantity and morphology of carbides and base microstructure are studied in the part cold-welded metal on the steel roll. Test result indicated that, by using Nb, Ti, V, Zr, RE as compound modifying agent, lots of fine carbides has precipitated and the network carbides distributed along column crystal boundary are controlled. Because carbon was fixed in the second phase , the formation of fine carbides had made the austenite "carbon poor" state, low carbon martensite was formed and high carbon martensite with bad toughness was avoided in the welded metal, and as-welded toughness and ability to prevent crack were remarkablly improved.

Key words: Arc cold-welding, Microstructure of welded metal as-welding, Steel roll