INVESTIGATION ON STRESS-CORROSION CRACKIN G OF AUSTENITIC STEELS IN COLD CHLORIDE SOLUTIONS

At ambient temperatures of about 25 degrees C austenitic chromium nick el steels can suffer stress corrosion in media with a concentration of both hydrogen ions and chloride ions exceeding 1 mol/L or in strongly concentrated chloride solutions. With the aid of constant strain rate testing and with U-bend specimens the parameters of this types of cor rosion were investigated. Contrary to the situation with the acid solu tions, the reproducibility of test results with the concentrated chlor ide solution was found to be low. The formation of martensite by cold working was found to be essential. The corrosion susceptibility decrea ses with increasing nickel content. Stress corrosion takes place withi n small critical potential ranges without a limit to more positive pot entials as this is the case of stress corrosion with hot media. These potential ranges are widened with increasing cold working especially i n the case of strongly grinding or cyclic loading in the plastic range . Corrosion cracking was observed with solutions of MgCl2, LiCl, with a less amount with NaCl, but not with ZnCl2. The concentration of chlo ride ions have an effect for solutions with a given kind of salt, but not for different salt solutions.