Effects of Y-based rear earth (RE) on microstructure and properties of 51CrV4 spring steel

the 51CrV4 spring steel modified by Y-based rare earth (RE) was designed. The effect of Y-base RE on microstructure and properties of the steel was comparative studied using uniaxial tensile testing machine, scanning electron microscopy (SEM) and room temperature impact testing. The results show that the strength and hardness of the spring steel decreased gradually with the increase of tempering temperature, but the contraction of area can be increased. The strength, especially for yield strength can be obviously improved, which attributed to the Y-based RE can inhibit the formation of carbide during tempering. The REOS compound inclusions formed by the reaction between RE and oxygen, sulfur in spring steel, which can significantly improve the impact toughness of spring steel.