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 tes ts in the mixed melted salt verified that hydrogen-induced cracking (H IC) could occur at 160 degrees C if sufficient hydrogen could be suppl ied continuously. It was found that the threshold SCC intensity factor s of both 321 and 310 steels were lower than those of HIC during dynam ic charging at high fugacity at 40 degrees C and 160 degrees C. In add ition, anodic polarization decreased hydrogen concentration and promot ed SCC in hot LiCl solution, while cathodic polarization increased hyd rogen concentration and restrained SCC. Hydrogen could be introduced i nto the specimen and be concentrated at the crack tip during SCC. It c ould promote anodic dissolution and SCC remarkably, although it was no t enough to produce cracking.