Influence of FBR plant service and repair welding on microstructure and residual stress of austenitic stainless steel weld joint
小原 智史 Satoshi OBARA 高屋 茂 Shigeru TAKAYA 若井 隆純 Takashi WAKAI 浅山 泰 Tai ASAYAMA 鈴木 裕士 Hiroshi SUZUKI 齊藤 徹 Toru SAITOH Laurent MARTIN
304SS 316LSS Austenitic Steel Aged Welded Joint Hardness Microstructure Repaired Welded Joint RESA RESA-Ⅱ Residual stress Used for 88000h at 526-545℃ in Phenix
For the commercialization of fast breeder reactors (FBR), it is essential to enhance the economic competitiveness by reduction of total cost by elongation of plant service period. In this point of view, it is important to establish the assessment method of integrity of aged weld joint and repair welding for the components of future long life FBR. In the present study, evolution of microstructure is evaluated for the 304SS-304SS weld joint which was used for 88,000h at 526-545°C in the French proto-type fast reactor Phenix (as secondary pipes), and for the repair weld joint made from the 304SS of Phenix and new 316LSS plate. In addition, residual stress of the joints were measured by means of RESA and RESA-II. As the results, the microstructure and the residual stress of the joints had changed in the high temperature-long service environment and by the repair welding, and those of the repair weld joint were correlated with its hardness. Since some creep tests of aged and repaired welded joints are continued, the long term stability of microstructure and mechanical properties need to be investigated in the future.