On the pitting behaviour of laser powder bed fusion prepared 316L stainless steel upon post-processing heat treatments

Abstract

Type 316L stainless steel manufactured by laser powder bed fusion (LPBF) in conjunction with appropriate post-treatment has been demonstrated to offer superior pitting resistance and a distinct pitting mechanism compared to wrought 316L. This work examines the effect of post-processing annealing time, temperature and microstructural changes on the pitting behaviour of LPBF 316L using potentiodynamic and potentiostatic polarisation in 0.6 M NaCl. Preferential pitting at melt pool boundaries was observed, due to heterogeneity of micro-strain or lattice imperfection. High temperature annealing resulted in the transformation of amorphous oxides with associated Cr-depletion, leading to a reduction of Epit and Erp. Show more