Stress Corrosion Behavior Of Maraging Nickel Steels In Natural Environments

Abstract

Abstract Stress corrosion cracking behaviors of several laboratory and commercially produced heats of 18, 20 and 25 percent Ni maraging steels have been observed in marine and industrial atmospheres and in sea water. Resistance of 18 percent Ni maraging steels was strongly affected by their structure and thermal histories. In properly processed materials rate of growth of stress corrosion cracks was low in most environments tested, and many stressed specimens lasted more than 500 days. Lower-yield-strength 18 percent Ni maraging steels were more resistant to stress corrosion cracking than higher strength alloys, also more resistant to hydrogen cracking when cathodically protected in sea water. Composition affected behavior of maraging steels, 20 percent Ni materials having relatively poor resistance and 25 percent Ni maraging steels good resistance, particularly in anoveraged condition. Control specimens of AISI 4340 steel hardened to 240-ksi yield strength failed rapidly in all test environments and conditions.