Influence of Rare Earth on Structure and Properties of High Carbon High Speed Steel

Some rare earth(RE) is added to high carbon high speed steel whose compositions are as follows: Fe-5%V-5%W-5%Mo-5%Cr-3%Nb-2%Co-2%C.The effects of RE on the as-cast microstructure,heat treatment microstructure and mechanical properties of high carbon high speed steel have been investigated.Results show that, when suitable RE is added into high carbon high speed steel,the austenite and eutectic carbides have been changed.The austenite grains and coarse eutectic structure are refined,and flake carbides in eutectic structure become short and thinner.After heat treatment,most of eutectic carbides are spheroidized and distributed(uniformly.) The hardness and hot hardness of modified high carbon high speed steel are slightly increased,impact toughness is greatly(increased) by 37.81% and reaches 10.17J/cm~2.The mechanism that RE improves the structure and properties of high carbon high speed steel is analyzed.