The effects of REM on steels are diverse. Their use not only results in efficient globularization of non-metallic inclusions but also makes it possible to change conditions under which castings solidify.
Formation of REM hydrides promotes high corrosion resistance of steels. REM, in their turn, are capable of forming high-melting and hard intermetalliс compounds (intermetallics) with non-ferrous metals, which eliminates intercrystalline low- and high-temperature brittleness thus increasing the plastic properties of steels.
REM significantly influence conditions under which steels solidify modifying the macro- and microstructure of ingots and castings. REM oxides, sulfides and nitrides as well as intermetallics produce a modification effect on the structure of steels, contributing to their strength. Additions of REM decrease the segregation of liquating elements (carbon, sulfur and phosphorus), reduce the value of the columnar zone, the size of equiaxed crystals and the distance between dendritic branches. This deeper impact on the structure of steels significantly improves the crack resistance of ingots undergoing subsequent forging.