Micro-alloying Effects of Yttrium on Recrystallization Behavior of an Alumina-forming Austenitic Stainless Steel

Micro-alloying effects of yttrium on the recrystallization behavior of an alumina-forming austenitic (AFA) stainless steel were investigated. It was found that the grain growth kinetics of the steels doped with different amounts of yttrium (i. e., 0, 0.05 and 0.10 mass% Y) could be described by an Arrhenius type empirical equation. Added Y could interact with carbon and influence the morphology of carbides both inside grains and on the grain boundaries, thus altering the grain boundary mobility and grain growth. The steel doped with 0.05 mass% yttrium showed the highest activation energy of grain growth and the most retarded recrystallization behavior, which mainly resulted from the high density of fine carbides both inside grains and on the grain boundaries. However, excess addition of 0.10 mass% Y induced coarsening and then lowered density of carbides, which alleviated the yttrium effects. The results also manifest that micro-alloying of rare-earth elements such as yttrium is an effective way for controlling grain growth behavior during recrystallization of AFA steels, which may have great implications on engineering applications.