Effect of zinc on the environmentally-assisted fatigue behavior of 316 stainless steels in simulated PWR primary environment

Abstract

In a simulated pressurized water reactor (PWR) environment with 30 ppb of Zn and peak holding, the low-cycle fatigue (LCF) life of 316 SS increased about 3 times compared to that without them. For the specimens tested with Zn and strain holding, the crack tip oxide layer was enriched with Zn. Electrochemical analysis showed the oxide layer had higher impedance and less defect density, indicating less corrosion compared to oxide layers from non-Zn-injection conditions. Thus, the improvement in LCF life of 316 SS was attributed to crack tip oxide modification by the combined effect of Zn-addition and peak strain holding.