The precipitation tendency and stacking fault energy of Al-modified ultra-super ferritic stainless steels: An experimental and first-principles study

Abstract

Super ferritic stainless steels (SFSS) are prone to the precipitation of multiple brittle second phases, increasing the production difficulty and restricting their applications. In this study, Al is added to super ferritic stainless steel to facilitate industrial production with controlled precipitation of brittle phases. The precipitation and recrystallization of the Al-modified super ferrite stainless steel are investigated through experimental and first principles approaches. It is found the addition of Al can inhibit σ-phase and promote the precipitation of Laves phase. It also increases the surface energy of BCC-Fe and reduces the unstable stacking fault energy, leading to an increase in the ductility of the SFSS. The results provide theoretical guidance for further improvements of mechanical properties of Al-modified ultra-super ferrite stainless steel.