Chloride Stress Corrosion Cracking of Austenitic Stainless Steel—Effect of Temperature and pH★

Overstressed U-bends of Types 304 and 347 stainless steels were exposed to water containing chloride ions to determine the susceptibility of these steels to stress corrosion cracking between the temperatures of 165 F and 200 F. The pH was controlled at 6.5 to 7.5 and 10.6 to 11.2 for the tests. At the high pH, cracks appeared at the edges with little evidence of pitting. At the neutral pH, cracks were found at the edges and associated with pits. Sensitized Type 304 had longer and deeper cracks than annealed Types 304 and 347 in the same exposure time. Conclusion is made that chloride stress corrosion cracking of these steels in the temperature range of 165 F to 200 F is less severe than that experienced at 500 F and that specific conditions are required for corrosion cracking to occur at all. 3.2.2