Hot oxidation and corrosion behaviour of boiler steel fabricated by wire arc additive manufacturing

Boiler Steels undergo severe degradation in corrosion resistance due to oxide scale formation at elevated temperatures. In this study, the comparative hot oxidation and hot corrosion resistance of wire arc additive manufactured SS 308L (WAAM 308L) was examined in hot air and Na2SO4–60% V2O5 molten salt environments at 700 °C. The corrosion resistance at elevated temperature was analysed using thermo-kinetic curves, corrosion products, and morphology of the oxides. The hot oxidation kinetics revealed that WAAM processed SS 308L specimens has excellent resistance and the weight gain reached 3.10 mg/cm2 with thinner oxide scale formation. Hot corrosion kinetics of WAAM processed SS 308L specimens highlighted the higher weight gain (37.0 mg/cm2) in molten salt environment and is attributed to the acceleration of oxide scale formation by the salts at elevated temperatures. Also, the development of Ni3V2O8 and Fe2O3 along with the depletion of Cr2O3 significantly influenced the corrosion resistance at elevated temperatures. The findings of this study reveal the potential of WAAM to produce customized parts for high-temperature applications. [Display omitted] •Hot oxidation and corrosion resistance of WAAM 308L was examined for the first time.•Microstructure composed of austenitic and residual delta-ferrite (2.30 to 4.80 FN).•Oxides and spinal phases were formed in the WAAM 308L surfaces at 700 °C.•The formation of NiO, Cr2O3, and NiCr2O4 provided good corrosion resistance.•The formation of Ni3V2O8 and the breakdown of Cr2O3 reduces the hot corrosion performance.