Intergranular corrosion of stainless steel

Technical Report · Fri Mar 01 04:00:00 EST 1991

OSTI ID:6032583

Stewart, J; Wells, D B; Scott, P M; Williams, D E ^[1]

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1. AEA Industrial Technology, Harwell (UK)

Corrosion current pulses associated with the nucleation of microcracks and their movement across single grain boundary facets were detected for intergranular stress corrosion cracking (IGSCC) of sensitized type 304 stainless steel induced both by dilute thiosulphate solutions at ambient temperature and by high-purity oxygenated water at 289{degree}C (BWR conditions). Estimates of crack-tip dissolution width and current density were derived. Cracks initiated as a consequence of non-uniform deformation around grain boundaries, and most stopped after penetration of at most a few grain-boundary facets. The idea of microstructural barriers to the propagation of short stress corrosion cracks was developed; such barriers became less important as the chemistry of the environment became more aggressive; a simple statistical model, based on a jump probability to cross a barrier, was developed for crack advance, and in part for the statistics of failure by IGSCC. At ambient temperature and at higher strain, fatal cracks initiated from a pre-existing microcrack. Strain-induced martensite formation resulted in decrease with increasing strain in both microcrack nucleation frequency and penetration. Under BWR conditions, strain-induced martensite formation did not occur and the fatal crack appeared slowly to advance out from one of the longer apparently arrested, microcracks. 36 refs., 32 figs

• Research Organization: Electric Power Research Inst., Palo Alto, CA (USA); AEA Industrial Technology, Harwell (UK)
• Sponsoring Organization: EPRI; Electric Power Research Inst., Palo Alto, CA (USA)
• OSTI ID: 6032583
• Report Number(s): EPRI-ER-7247-Vol.1
• Country of Publication: United States
• Language: English

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