Anisotropic response in mechanical and corrosion performances of UNS S31803 duplex stainless steel fabricated by laser powder bed fusion

Abstract

Mechanical and corrosion behaviors perpendicular to build direction (XOY) and along build direction (XOZ) of UNS S31803 duplex stainless steel (DSS) fabricated by laser powder bed fusion (LPBF) were investigated. With the post-annealing, the steel exhibited a ferrite-austenite microstructure. For XOY plane, austenite displayed a primarily texture while ferrite kept preferred orientation, and mainly held a Nishiyama-Wassermann orientation relationship. However, for XOZ plane, austenite showed a mixed texture. The average size of ferrite grains was larger for XOZ plane than XOY. The austenite in XOY plane was mostly island morphology grains, while in XOZ plane, there were a large number of coarse columnar grains. A higher geometrically necessary dislocation density and proportion of low-angle grain boundaries on XOY plane were observed. The yield strength and ultimate tensile strength values perpendicular to build direction were higher than those along build direction. While the total elongation perpendicular to build direction was lower. Moreover, the XOY plane shows slightly better corrosion resistance than the XOZ.

Keywords

• Duplex stainless steel
• Anisotropic response
• Mechanical property
• Corrosion behaviour
• Laser powder bed fusion