TRIPマルエージング鋼の疲労特性：準安定ラメラ組織の効果

抄録

Fatigue properties of transformation-induced plasticity (TRIP) maraging steel were investigated by rotating bending fatigue testing. An initial microstructure of the TRIP maraging steel is maraging martensite with metastable austenite films. First, as we expected, precipitation hardening by intermetallic compound realized outstanding improvement of fatigue limit. In addition, compared to TRIP steel containing metastable austenite and pearlitic steel containing nano-laminate, the TRIP maraging steel showed superior fatigue limit and fatigue life at the same stress amplitude normalized by tensile strength. The higher fatigue limit is attributed to suppression of crack initiation owing to TRIP effect and subsequent transformation-induced crack closure (TICC). The higher fatigue life stems from roughness-induced crack closure (RICC). More specifically, the TRIP and TICC originates from the metastability, and the RICC was caused by the nano-laminate structure of the TRIP maraging steel.