CAST STEEL MICRO-ALLOYED WITH RARE EARTH

A cast steel micro-alloyed with rare earth. The cast steel has a chemical composition mainly comprising C, Si, Mn, Nb, Ti, Re, La, Ce, P, S, iron and trace impurities, wherein the contents of C, Si, Mn, Nb, Ti, Re, P and S, in mass percentage, are 0.40%-0.5% of C, 0.20%-0.30% of Si, 1.5%-1.69% of Mn, 0.1%-0.8% of Nb, 0.05%-0.12% of Ti, 0.02%-0.22% of Re, 0.01%-0.14% of La, 0.01%-0.19% of Ce, P ≤ 0.045%, and S ≤ 0.020%, respectively, and the total contents of Nb, Ti, La and Ce are less than or equal to 0.6%. The cast steel micro-alloyed with rare earth can greatly increase the yield strength and tensile strength without significantly reducing the plasticity and toughness. Compared to a common 35SiMn steel, the yield strength of the cast steel micro-alloyed with rare earth is increased by more than 60MPa and the tensile strength thereof is increased by more than 95MPa. L'invention concerne un acier coulé micro-allié aux terres rares. L'acier coulé a une composition chimique comprenant principalement C, Si, Mn,