Corrosion properties of 304L stainless steel made by directed energy deposition additive manufacturing.

• Lack of fusion pores controlled the breakdown potential (E b) to a first order, reducing it by up to 400 mV. • High heat input DED material observed a reduced E b attributed to chemical micro-segregation dictated by cooling rate. • The presence of δ overshadows the potentially beneficial effect to E b seen by nanoscale non-metallic inclusions. • Preferential dissolution of γ around the δ in DED material resulted in web-like pit covers and nest-like pit interiors. The impact of microstructure and processing defects of directed energy deposition (DED) 304L stainless steel on its corrosion behavior was investigated. Materials produced by DED with heat inputs of 0.45 and 0.03 kJ/mm were compared to wrought 304L. Lack of fusion pores in the DED material controlled breakdown potential (E b) to the first order, reducing it by up to 400 mV versus the base material in 0.6 M NaCl. The hierarchal control of these and other microstructure features, nanoscale oxides and δ -ferrite, and processing features on the E b of DED 304L is addressed. [ABSTRACT FROM AUTHOR]