CONTINUOUS OBSERVATION OF STRESS-CORROSIO N CRACKING PROPAGATION IN SUS304 STAINLESS-STEEL BY USING DIFFERENTIAL STRAIN TRANSFORMER

The effect of the deformation-induced martensite (alpha') on stress co rrosion cracking (SCC) for SUS304 austenitic stainless steel was inves tigated by measurements of the time to failure of stress corrosion cra cking for the specimens which contains (alpha') martensite under a loa ded stress of 0.2% proof stress and the creep strain during the SCC te st in 1 x 10(-2) kmol/m3 HCl+35 mass%MgCl2 solution at 358 K. The main results obtained from the experiments are summarized as follows: (1) The time to failure of stress corrosion cracking of the specimens are decreased with increasing volume fraction of martensite below 57%. How ever, there is no effect on the time to failure of stress corrosion cr acking of the specimens at the volume fraction of martensite higher th an 57%. (2) The effects HCl concentration and loaded stress on the tim e to failure are little for the specimens martensite contained. (3) Th e crack propagation of stress corrosion of the specimens proceeds at t wo stages. The crack propagation rates at the first stage and the seco nd stage increase with increasing volume fraction of martensite in SUS 304 stainless steel under the same experimental condition. However, th e rate is almost constant at the volume fraction of martensite higher than 33%.