Enhancing the repassivation ability and localised corrosion resistance of an additively manufactured duplex stainless steel by post-processing heat treatment

Duplex stainless steel (DSS) 2205 produced by laser powder bed fusion (LPBF) additive manufacturing was found to possess poor repassivation ability and weak resistance to localised corrosion. This was due to the nonequilibrium phase composition and elemental distribution in the as-built LPBF DSS affected by the rapid solidification inherent to LPBF processing. A short-time post-processing heat treatment at 1000 °C for 10 min followed by water quenching to room temperature was shown to be able to enhance the repassivation ability and localised corrosion resistance by retrieving the equilibrium dual-phase microstructure. A discussion is given on the mechanism behind such behaviour. • LPBF DSS showed a nonequilibrium microstructure consisting of 98% ferrite and 2% austenite with numerous Cr 2 N precipitates. • As-built LPBF DSS exhibited a weak repassivation ability and localised corrosion resistance. • Post-LPBF heat treatment enhanced the repassivation ability and resistance to localised corrosion. • Microstructural changes induced by post-LPBF heat treatment were identified as the reasons for repassivation enhancement.