ChemInform Abstract: The Effect of Heat Treatment and Applied Potential on the Stress Corrosion Cracking (SCC) of Alloy 600 in Thiosulfate Solution

Abstract

The Effect of Heat Treatment and Applied Potential on the Stress Corrosion Cracking (SCC) of Alloy 600 in Thiosulfate Solutionis investigated by using electrochemical potentiokinetic reactivation tests and modified Huey tests. Stabilization heat treatment (990 . degree.C/5 min + 705 • C/15 h) induces semicontinuous grain boundary carbide precipitation of Alloy 600 which causes a significant decrease in the degree of sensitization. The anodic polarization behavior of the alloy in 0.01 M Na2S2O3 solution at 95 • C is mainly associated with Cr in the alloy. As shown from the polarization curves, exhibiting 2 anodic peaks (-500 and +100 mV (SCE)) independent of heat treatment, the alloy passivates in thiosulfate solution and both the sensitized and the stabilized alloy exhibit intergranular stress corrosion cracking under applied potential conditions. The severity of this cracking depends upon the degree of sensitization. -(TSAI, M.-C.; TSAI, W.-T.; LEE, J.-T.; Corros.