Corrosion Resistance of Bellow Materials for Catalytic Cracking Unit

The susceptivity to stress-corrosion cracking (SCC) in H₂S_XO₄ and 15%NaCl +H₂S_XO₄ solution of Incoloy800H, Inconel625, B-315, FN-2 and 316 bellow materials in solid solution annealed and cold-worked conditions is investigated. The results show that SCC in H₂S_XO₄ occurs only in samples of Incoloy800H and later with solution annealed samples than with cold-worked samples, but pitting corrosion occurs in all samples in 15% NaCl+H₂S_XO₄ solution. For the same material, the resistance of cold-worked samples to pitting corrosion is more excellent than that of solid solution annealed samples and for different materials, the resistance to pitting corrosion reduces from Inconel625 to B-315, FN-2 and 316 in sequence.