THE ROLE OF HYDROGEN IN STRESS-CORROSION CRACKING OF AUSTENITIC STAINLESS-STEEL IN HOT MGCL2 SOLUTION

The role of hydrogen in stress-corrosion cracking (SCC) of austenitic stainless steel was investigated in boiling chloride solution. The tests in the mixed melted salt verified that hydrogen-induced cracking (HIC) could occur at 160 degrees C if sufficient hydrogen could be supplied continuously. It was found that the threshold SCC intensity factors of both 321 and 310 steels were lower than those of HIC during dynamic charging at high fugacity at 40 degrees C and 160 degrees C. In addition, anodic polarization decreased hydrogen concentration and promoted SCC in hot LiCl solution, while cathodic polarization increased hydrogen concentration and restrained SCC. Hydrogen could be introduced into the specimen and be concentrated at the crack tip during SCC. It could promote anodic dissolution and SCC remarkably, although it was not enough to produce cracking.