Electrochemical noise comparative study of pitting corrosion of 316L stainless steel fabricated by selective laser melting and wrought

Abstract

• Two kinds of 316L stainless steel were fabricated by SLM with laser scanning speed of 600 mm/s and 1200 mm/s. • Pitting behavior of the SLM 316L was comparatively studied with wrought 316L by electrochemical noise (EN). • Three shapes of EN transient corresponding to the pits initiated by inclusion, gas pore and LOF pore were identified. • The higher pitting resistance of SLM 316L is controlled by the poorer ability of pit growth. Two kinds of 316L stainless steel (SS) were fabricated by selective laser melting (SLM) technique with laser scanning speeds of 600 mm/s and 1200 mm/s. The pitting corrosion behavior of the SLM 316L SS was comparatively studied with the wrought 316L SS by using potentiodynamic polarization and electrochemical noise (EN) technique. It was found that the pitting potentials of SLM 316L samples were higher than that of wrought sample. Three shapes of EN transient corresponding to the pits initiated by non-metallic inclusions, gas pores and lack-of-fusion (LOF) pores were identified. According to the results of wavelet and stochastic analysis, it was revealed that the higher pitting resistance of SLM 316L was controlled by the poorer ability of pit growth. The potential application of using EN technique to evaluate LOF pores in SLM parts is discussed.