The history of the application of rare earth in the field of steel casting can be traced back to the early 1950s. American steel foundries added rare earth to the steel casting used to manufacture armor. It was found that the as cast structure, inclusion morphology, liquid steel fluidity and so on of the steel casting were significantly improved, and the impact toughness of the steel casting was also significantly improved. Since then, metallurgical researchers all over the world began to pay attention to the addition of rare earth elements.
In the 1980s, China carried out research on the application of rare earth elements in cast steel. It was found that the addition of rare earth elements in cast steel can desulfurize, purify and refine the as cast structure, which can improve the fluidity of molten steel and the hot crack resistance of castings, reduce linear shrinkage and segregation and other good effects. It has been pilot produced in many steel casting plants.
When developing low alloy high strength and toughness rare earth cast steel, Dong Li added rare earth composite treatment agent by feeding wire outside the furnace and blowing argon at the bottom of the ladle to promote liquid steel mixing and inclusion floating. The amount of rare earth was 0.05%~0.1%, and the content of rare earth in the steel was 0.010%~0.015%. The tensile strength of the developed rare earth cast steel increased by 11.2%~33.9%, and the yield strength increased by 28.6%~36.3%. R. The research work of b.tuttle and his team also shows that adding an appropriate amount of rare earth to low alloy cast steel can refine the grain size of cast steel, increase the strength by at least 13%, and increase the elongation by at least 20%. Huowenxia’s research results show that the as cast hardness of wear-resistant cast steel without rare earth is 48.8hrc, and the hardness of wear-resistant cast steel with rare earth content of 0.042% reaches 58.8hrc, an increase of 10hrc. After zangqiyu added no more than 0.034% rare earth element Y to 30cr13 cast martensitic stainless steel, the high temperature oxidation resistance of cast steel was significantly improved.