On the effect of build orientation and residual stress on the corrosion of 316L stainless steel prepared by selective laser melting

Highlights: • Microstructural anisotropy was associated to extremely fast SLM heating/cooling cycles. • SLM 316 L specimens presented superior resistance to pitting than their wrought counterpart in 0.6 M NaCl. • Small lattice disturbances caused by residual stresses did not influence pitting susceptibility. • Nano segregation on the sub-cellular boundaries of the vertical orientation caused lower pitting resistance for this build direction. • Horizontal build orientation produced samples with the highest resistance against pitting. During additive manufacturing of AISI 316 L stainless steel, heating and cooling cycles from selective laser melting (SLM) are responsible for grain anisotropy in the 'as-built' condition. Columnar grains form on the plane parallel to the build orientation, whilst equiaxed grains are observed on planes perpendicular to the build orientation. Anisotropy may affect corrosion and pitting of this alloy. In addition, residual stresses originating from the rapid heating and cooling inherent to SLM, may also influence corrosion and pitting of 316 L stainless steel. Electrochemical and immersion testing was carried out for 316 L as a function of build orientation and residual stresses.