Assessment of Hot Corrosion in Molten NaSO and VO of Inconel 625 Fabricated by Selective Laser Melting versus Conventional Technology.

Inconel 625 samples, obtained by Selective Laser Melting (SLM) and conventional technology, were tested for hot corrosion resistance against a molten mixture of NaSO and VO. The assessments were performed in air, at 900 °C with exposure time of up to 96 h, and at 1000 °C for 8 h. Weight gain was higher for samples obtained by SLM, with 37.4% after 8 h, 3.98% after 24 h, 4.46% after 48 h, and 5.8% after 96 h at 900 °C (22.6% at 1000 °C, 8 h). Three stages of corrosion were observed, the first and last with a high corrosion rate, while the second one showed a slower corrosion rate. Corrosion behaviour depends on the morphology of the grain boundary, which can influence the infiltration of corrosive salts, and on the formation of CrNiO compound, which acts as a temporary barrier.