Evaluation method of creep-fatigue life for 316FR weldment
316FR鋼溶接継手のクリープ疲労寿命評価法
永江 勇二 ; 山本 賢二*; 大谷 知未*
Nagae, Yuji; Yamamoto, Kenji*; Otani, Tomomi*
The most important failure mode to be prevented is creep-fatigue at elevated temperatures in fast reactors. 316FR stainless steel is a candidate material for the reactor vessel and internal structures. Evaluation method for creep-fatigue life, based on the time fraction rule, has been already developed in base metal of 316FR stainless steel. Development of procedure in evaluating creep-fatigue life is also necessary for the weldment of 316FR stainless steel by using similar filler or 16-8-2 filler. Compared between mechanical properties of weldment and those of base metal, strength-reduction factors for weldment have been evaluated. Strength-reduction factor for fatigue has been proposed. It is considered that strength-reduction factor for creep strength is not necessary. Creep-fatigue life could be evaluated for weldments of similar filler and 16-8-2 filler in the same way, because a difference in mechanical properties between both filler metals is negligible. Creep-fatigue life by the time fraction rule using analytical relaxation curve for weldments were compared with experimental data, and the evaluation method of creep-fatigue life for the weldments of 316FR stainless steel has been proposed.