Abstract: Sulfide stress corrosion cracking (SCC) behavior of 3Cr17Ni7Mo2SiN stainless steel (SS) is investigated by using slow strain rate test(SSRT), U-bent specimen immersing test and fractography observation by scanning electronic microscopy(SEM). 3Cr17Ni7Mo2SiN SS is subject to SCC in test solutions containing NaCl (5% in mass) and H2S (no less than 0.1%) within pH range of 2.7 to 4.5. The time to SCC occurrence of 3Cr17Ni7Mo2SiN SS increases with the rising of pH or with the lowering of mass fraction of H2S. SCC under a low pH (pH=2.7) condition grows faster than that under a high pH condition, which initiates in an intergranular mode and then propagates transgranularly, however, in a high pH (pH=4.5) solution, SCC growth is slow with a blunt cracktip due to anodic dissolution mechanism. Inclusions, effects of hydrogen induced cracking (HIC) and corrosion pits will promote the occurrence of SCC.

Key words: Hydrogen sulfide, Stainless steel, Stress corrosion cracking(SCC)