Existing capabilities to quantitatively model carbide precipitation and sensitization development in austenitic stainless steels are assessed and critically analyzed. A theoretically based, empirically modified model is described that predicts carbide nucleation kinetics, chromium depletion characteristics, and material degree of sensitization (DOS) as measured by the electrochemical potentiokinetic reactivation (EPR) test. Individual model components are validated by correlation to the available database including direct comparisons to grain-boundary chromium depletion. The model is shown to quantitatively predict isothermal sensitization development in a large number of commercial type 304 (UNS(1) S30400) and 316 (UNS S31600) stainless steel (SS) heats. This work represents a first step to evolve methods that realistically assess microstructural characteristics and structural reliability in stainless steel components and weldments.

Subject
Materials, Carbides, Thermodynamics, Molybdenum, Precipitation (solids), Composition, Diffusion, Chromium, Nucleation, Heat, Sensitization, Carbon, Stainless steel
Keywords:
carbide nucleation, carbide precipitation, chromium depletion, intergranular corropsion, modeling, sensitization, sensitization testing, stainless steel, stress corrosion cracking, 304
National Association of Corrosion Engineers
1990
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