The influence of heat treatments on the intergranular attack (IGA) and intergranular stress corrosion cracking (IGSCC) resistance of Inconel(1) 690 (UNS(2) N06690) were studied. The chromium profiles adjacent to the grain boundary were predicted by thermodynamic and kinetic modeling and benchmarked with experimental results. The relative susceptibilities of alloy 690 with various heat treatments to stress corrosion cracking (SCC) in 0.001 M Na2S2O2 and low pH at room temperature were evaluated. The results of slow strain rate tensile (SSRT) testing showed good IGSCC resistance of alloy 690. The results of the Huey test showed very little weight loss for various heat treatments. The good resistance of IGA and IGSCC for alloy 690 are considered to be attributed to the higher equilibrium chromium concentration at the intergranular carbide-matrix interface.

Subject
Grain size, Carbides, Intergranular stress corrosion cracking, Thermodynamics, Hydrogen concentration, Chromium, Solubility, Interfaces, Carbon, Annealing, Grain boundary, Alloys, Heat treatment
Keywords:
chromium depletion, IGA, IGSCC, alloy 600, alloy 690, sensitization
National Association of Corrosion Engineers
1990
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