Effect of rare earth elements on the segregation behavior and microstructure of super austenitic stainless steel

Super austenitic stainless steel (SASS) was prepared by non-consumable vacuum arc melting for the first time. The effects of rare earth (RE) elements on its solidification microstructure and segregation behavior were investigated. The σ phase is the main precipitation phase in SASS. The addition of RE elements can refine the solidification microstructure and the dendrite spacing. The addition of RE elements reduced the secondary dendrite spacing at top (S1) by 5.22 μm. The elements as Cr, Mn, and Mo have positive segregation, and elements as Ni and Fe have negative segregation. The addition of RE elements has the trend of reducing element segregation, thereby inhibiting the σ phase precipitation. And the addition of RE reduces the hardness of the secondary phase.