Failure propensity of austenitic stainless steels by chloride induced stress corrosion cracking in air

Abstract

Chlorides induced stress corrosion cracking (ESCC) behavior was examined for SUS304L, SUS316L and SUS304 stainless steels (SS) after depositing synthetic sea water simulating sea salt particles at a temperature range from 333 K to 353 K with relative humidity of 35%. A stress-ESCC failure time relationship was formulated for SUS304L SS as σ = -Alog (tf) + B, where σ: applied stress (MPa), tf: time to failure (h), A = 23.7T-7020, B = 43.7T-11600, T: absolute temperature (K). Even an incipient micro-crack was not observed on the specimen surface of the SS at the applied stress level of 0.25 σy (σy: 0.2% proof stress), although SCC initiated at the applied stress level of 0.5 σy. Thus the threshold stress should be between 0.5 σy and 0.25 σy, for these SS, and the threshold stress would rise beyond these values if the stress concentration be considered at the bottom and circumference of a pit. A statistical analysis suggested that the ESCC crack length and crack depth conformed to the double exponential distribution.