Sustainability of compressive residual stress by stress improvement processes
西川 聡 Satoru NISHIKAWA 大北 茂 Shigeru OKITA 山口 篤憲 Atsunori YAMAGUCHI
Austenitic stainless steelLPNickel base alloyPolishingSPStress improvement processesSustainability of the compressive residual stressUSPWJP
Stress improvement processes are countermeasures against stress corrosion cracking in nuclear power plant components. It is necessary to confirm whether compressive residual stress induced by stress improvement processes can be sustained under operation environment. In order to evaluate stability of the compressive residual stress in 60-year operating conditions, the 0.07% cyclic strains of 200 times at 593 K were applied to the welded specimens, then a thermal aging treatment for 1.66×106 s at 673 K was carried out. As the result, it was confirmed that the compressive residual stresses were sustained on both surfaces of the dissimilar welds of austenitic stainless steel (SUS316L) and nickel base alloy (NCF600 and alloy182) processed by laser peening (LP), water jet peening (WJP), ultrasonic shot peening (USP), shot peening (SP) and polishing under 60-year operating conditions.