Mitigation of Stress Corrosion Cracking Using an Engineered Residual Stress Solution

Author:  Scheel, Hornbach, Prevey
Source:  Conf Proc 2011: ICSP-11 South Bend, IN USA (pgs. 273-278)
Doc ID:  2011045
Year of Publication:  2011
Abstract:  
Abstract Stress corrosion cracking (SCC) is known to be the result of the combined influence of tensile stress and a corrosive environment on a susceptible material. Austenitic stainless steels such as types 304L and 316L are susceptible alloys often used in nuclear applications. Tensile residual stresses are developed in components by cold working, forming, prior machining, grinding and welding. In many cases tensile residual stresses in the heat affected zone of weldments can reach the yield strength of the material. SCC can be mitigated or eliminated by introduction of an engineered compressive residual stress field into components via low plasticity burnishing (LPB). SCC testing results comparing LPB treated and un-treated 304L and 316L stainless steel weldments are presented. Residual stress results are shown for 304L and 316L stainless steels and Ni based Alloy 22. The results show conclusively that the deep, stable compression produced by LPB eliminates SCC in austenitic weldments, regardless of sensitization from welding. The successful application of LPB to mitigate SCC in Alloy 22 closure welds on full size nuclear waste containment vessels is discussed. Keywords: Stress Corrosion Cracking, Low Plasticity Burnishing, Residual Stress, Weldments, Austenitic Stainless Steels