Susceptibility to atmospheric stress corrosion cracking of laser-based powder bed fusion 316L

This work aims to assess the susceptibility to stress corrosion cracking (SCC) of additively manufactured (AM) 316L stainless steel by laser-based power bed fusion (PBF-LB) and compare its performance with conventional manufacturing (CM), i.e. wrought 316L. Also, the influence of different surface conditions was analyzed. Potentiodynamic polarization tests in artificial seawater were used to obtain electrochemical properties, such as pitting breakdown potential (E bd ) and corrosion potential (E corr ). Stress corrosion cracking susceptibility was measured using U-Bend specimens, using concentrated artificial seawater droplets, simulating non-rinsing atmospheric conditions in marine environments. The specimens were exposed to temperatures between 40 and 60 °C and relative humidity of 40 %. For the AM specimens, two surface conditions were tested: as built and after machining process. A higher threshold temperature was observed for 316L-AM, indicating a better SCC resistance, than the 316L-CM, hence L-PBF can be used as an alternative manufacturing route for replacing 316L-CM as better properties were achieved. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and superficial residual stress measurements were used to aid the discussion of the SCC results. These tests revealed better passive layer properties in the AM material and formation of strain-induced martensite in the CM after bending, leading to higher residual stress.