BARC/PUB/2004/0166

 
 

Role of Environmental Variables on the Stress Corrosion Cracking of Sensitized AISI Type 304 Stainless Steel (SS304) in Thiosulfate Solutions

 
     
 
Author(s)

Roychowdhury, S.; Ghosal, S. K.; De, P. K.
(MSD)

Source

Journal of Materials Engineering and Performance, 2004. Vol. 13 (5): pp. 575-582

ABSTRACT

The stress corrosion cracking (SCC) behavior of sensitized AISI type 304 stainless steel (SS304) has been studied in dilute thiosulfate solutions as a function of thiosulfate concentrations and applied potentials. The susceptibility to SCC was observed to increase with thiosulfate concentrations and applied potentials. The addition of boric acid produced the reverse effect. A critical potential was found to exist, below which no SCC took place. Potential fluctuations, as recorded in the tests under open circuit conditions, appeared to be correlated with crack initiation and propagation during SCC. Current fluctuations observed in the controlled potential tests also gave indications of crack nucleation; however, at higher applied potentials such fluctuations were absent. The formation and presence of martensite in the specimens seemed to have a minor role in the overall SCC process. The aggressiveness of the thiosulfate concentration was also an important factor in determining the degree of susceptibility to SCC. The results obtained in the slow strain rate tests under open circuit as well as under potential-controlled conditions suggested a film ruptureanodic dissolution type of mechanism operative during SCC of sensitized SS304 in thiosulfate solutions.

 
 
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