Interpretation of TTS experiment : Comparison of creep fatigue evaluation methods of weldment

kasahara, Naoto; Laurent LE BER*

For considering strength reduction of weldments in elevated temperature components, CEA and JNC have developed design evaluation procedures. Both procedures were applied to the same benchmark problems and their results were compared under EJCC contract. One of benchmarks that provided by JNC is creep-fatigue evaluation of a welded vessel subjected to cyclic thermal transient loading. The objective of this problem is comparison of total strength evaluation methods of base metal and welded joints against actual loading conditions. This report compared results of the JNC problem evaluated by both procedures from view points of material properties, strength evaluation of base metals, and strength reduction evaluation of welded joints. Main differences of procedures were found in strain concentration evaluation methods of base metal, initial stress evaluation methods of relaxation, fatigue strength reduction factors of weldments, and creeep strength reduction factor of weldments. Both of CEA and JNC procedures were confirmed to be conservative for weldments of 316FR.