Abstract: By adjusting the Cr, Ni equivalent to regulate the δ-ferrite content in the austenitic stainless steel weld deposited metal bearing high Si and N. The effect of solidification mode on the corrosion performance of the weld deposited metal in the high-temperature, concentrated nitric acid solution containing oxidizing ions was investigated by employing characterization means including metallographic microscopy, scanning electron microscopy, and electron probe microanalysis. The results demonstrate a "υ"-shaped trend between the corrosion rate of the weld and the increase in δ-ferrite content. The minimum corrosion rate of 0.05066 mm/a was achieved at a δ-ferrite content of 5.5%. Galvanic coupling corrosion formed between δ-ferrite and austenite owing to their electrochemical potential difference, leading to preferential corrosion of δ-ferrite. Furthermore, the Cr_{equivalent (eq)}/Ni_eq ≥ 1.51 results in a transition of the weld solidification mode from Austenitic-Ferritic (AF) to Ferritic-Austenitic (FA). Concurrently, the corrosion rate undergoes a decline of approximately 13%. The corrosion morphology of the molten metal in the AF mode is characterized by a corrosion groove, whereas the corrosion morphology in the FA mode is typified by a corrosion pit.

Key words: High SiN austenitic stainless steel, Nitric acid corrosion, Weld deposited metal, Solidification mode, δ-ferrite