L-PBF fabrication of 2507 duplex stainless steel: corrosion resistance in marine conditions

Purpose This study aims to explore the corrosion response of 2507 duplex stainless steel (DSS) manufactured by laser powder bed fusion (L-PBF) and subsequently solution annealed, aiming to determine its performance in chloride-rich marine service. Conventional rolled steel was also tested for benchmarking to assess the feasibility of L-PBF as an alternative route for producing advanced DSS components. Design/methodology/approach Samples were fabricated under optimized L-PBF parameters and heat-treated at 1000, 1050 and 1100 °C. Microstructural evolution was characterized using X-ray diffraction, a scanning electron microscope and electron backscatter diffraction. Electrochemical behavior was investigated through impedance spectroscopy (EIS), potentiodynamic polarization, Mott–Schottky analysis and X-ray photoelectron spectroscopy (XPS) in both NaCl solution and simulated shallow- and deep-sea conditions. Findings Solution treatment increased austenite fraction and restored the ferrite/austenite ratio while leaving hardness largely unchanged. L-PBF specimens showed corrosion resistance comparable to and in shallow seawater sometimes exceeding, that of rolled steel. In contrast, heat treatment at 1100 °C decreased resistance owing to phase boundary alterations and destabilized passive films. Mott–Schottky and XPS data further confirmed that passive films on L-PBF samples remained relatively robust, whereas high-temperature annealing introduced electronic and chemical instabilities under deep-sea conditions. Originality/value The study delivers one of the earliest systematic assessments of L-PBF 2507 DSS subjected to heat treatment in marine environments. It highlights the dual influence of annealing and provides guidance for process optimization, supporting the use of L-PBF DSS in offshore and subsea engineering applications.