A Study on the Precipitation of σ Phase in Super Duplex Stainless Steel

슈퍼 2상 스테인리스강의 σ상 석출에 관한 연구

This study was carried out to investigate the influence of ${\sigma}$ phase on the microstructure and mechanical properties in super duplex stainless steel. The precipitation of ${\sigma}$ phase during isothermal heat treatment showed the type S curves with a certain incubation period. The precipitation of ${\sigma}$ phase was precipitated at ferrite phase and interface of ferrite and austenite. Under the state of isothermal transformation, the precipitation of ${\sigma}$ phase was stimulated by applied stress. With increasing of volume fraction of precipitated ${\sigma}$ phase, tensile strength was increased and elongation was decreased with linear relationship, while in case of precipitated ${\sigma}$ phase was 5% over, impact value was rapidly decreased.