Stress corrosion cracking of 316LN stainless steel with orthogonal scratches

Abstract

316LN stainless steel is used to produce the third generation primary circuit pipe of pressurized water reactor (PWR). Its internal and external pipe surfaces are generally introduced with scratches when manufactured, transported and installed processes, making their research and discovery on the stress corrosion cracking (SCC) sensitivity challenging. In the present study, multiple orthogonal scratches on 316LN stainless steel are prepared using the rotary cutting head. The effects of the orthogonal scratches on the SCC of 316LN stainless steel are investigated. The experimental results show that the force bearing point of this kind of rotary cutter head is near 60° on the side, which is different from the common cutter head. At the intersection of orthogonal scratches, larger strain concentration and more oxide particles can be formed comparing with single scratch. With increasing strain concentration, the more nucleation sites and the greater growth driving force for the oxide particles can be formed. Thus larger and more oxide particles in this case are generated, resulting in finally a greater SCC sensitivity.