Life prediction by mechanistic modeling and system monitoring of environmental cracking of iron and nickel alloys in aqueous systems

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 1988-08, Vol.103 (1), p.167-184
• Main Authors: Andresen, Peter L., Peter Ford, F.
• Format: Article
• Language: English
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/0025-5416(88)90564-2

Environmentally assisted cracking of structural components is a life-limiting factor in the operation of, for example, light-water reactors, fossil plants, steam and gas turbines, nuclear waste containment and deaerators. In the context of an overall emphasis on light-water reactors, the shortcomings of existing design and life evaluation codes are highlighted and an improved approach is presented on the basis of the application of fundamental mechanistic understanding and a quantitative model of environmental crack advance. The integration of this model with real-time chemical sensors and reference crack growth monitors permits enhanced control and management of cracking in structural components. Validation of this approach was performed using laboratory and field data for specimens and prototypical components. For nucleaar steam supply, an on-line monitoring and predictive modeling framework has been developed for both in-core and out-of-core structural components fabricated from types 304 and 316L stainless steel, A533B and A508 low alloy steel, and Inconel 600 and Inconel 182 alloys. The conceptual and quantitative formulation of the film rupture-slip dissolution mechanism of crack advance is reviewed. The analyses and independent evaluation of the crack tip environment, chemical reaction rates and stress-strain fields, common to all fundamental models for environmentally assisted cracking are summarized. On the basis of these data, theoretical predictions of the subcritical crack propagation rate were made for different steady state and transient conditions of environment (e.g. degree of aeration of water purity), material (e.g. degree of grain boundary