High-Nitrogen, High-Nickel Fe-Ni-Cr Alloys for Stress Corrosion Cracking Resistance in Nuclear Environments

摘要

Stress corrosion cracking (SCC) has been a recurring problem in nuclear power stations of both, the boiling water type (BWR) and the pressurized water type(PWR). Stress corrosion cracking service failures have been particularly numerous with austenitic stainless steels in BWR and the austenitic nickel rich alloy 600 in PWR, thus in fcc solid solutions of Fe, Cr- and Ni. While it has long been known that cold work will make alloys more susceptible to SOC, it is a recent observation that in the cold worked condition, austenitic stainless steel can fail by stress corrosion cracking not only in BWR but also in FWR reactor coolant, where they have been thought to be SCC-resistant until a few years ago. The present paper reports on the complete SOC resistance of a group of austenitic Fe-Cr-Ni solid solutions with about equal contents of these three alloying elements plus a high concentration of nitrogen. These alloys are SOC resistant even in the high-strength condition after severe cold work. These alloys resist stress corrosion cracking in nuclear reactor coolants where no other high-strength materials resist. They have therefore a potential for application in future reactors where stress-corrosion cracking must not occur.