Evaluation of Electromagnetic Characteristics under Creep-fatigue Damage Process at Weld Region for Energy Structural Materials

Abstract

Creep-fatigue damage for welded specimens of austenitic stainless steel SUS316FR and high-chromium steel Mod.9Cr-1Mo was investigated by magnetic characterization techniques such as vibrating sample magnetometry and magnetic force microscopy. In SUS316FR at weld metal region remanent magnetic flux density decreased as creep-fatigue strain increased and it resulted from the decrease of δ-ferrite at weld metal region. In Mod.9Cr-1Mo steel at weld metal region permeability increased and micro-vickers hardness decreased as creep-fatigue damage increased and it resulted from magnetic domain structures change during creep-fatigue. It was found that the creep-fatigue damage for these energy structural materials was related to magnetic characteristics change which caused by micro-magnetic structure.