Microstructure and high temperature performance of 321 SS wall manufactured through wire plus arc additive manufacturing

The main aim of the present work is to examine the microstructure and high-temperature corrosion performance of wire + arc additive manufactured (WAAM) 321 stainless steel (321 SS) specimens exposed to molten Na2SO4 + 60%V2O5 salt and air atmosphere at 700 degrees C under cyclic conditions. The as-built specimens presented a typical layered microstructure with delta-ferrite in the austenite matrix along with small fraction of TiC. The corroded specimen exhibits a high weight gain compared to the oxidized sample, which is attributed to the deposited molten salt. The cracks were developed on the corroded sample attributed to the fluxing of oxides by vanadium and sulphur. Due to good adherent of scale to the steel no spallation were noticed till end of study in both the atmosphere suggesting that WAAM produced steel is suitable for the boiler environment up to 700 degrees C.