Effects of lamella size and connectivity on fatigue crack resistance of TRIP-maraging steel. (July 2017)

• Record Type: Journal Article
• Authors: Zhang, Z.; Koyama, M.; Wang, M.M.; Tsuzaki, K.; Tasan, C.C.; Noguchi, H.
• Is Part Of: International journal of fatigue. Volume 100:Part 1(2017)
• Page Start: 176
• Page End: 186
• Publication Date: 2017-07
• Subjects: Transformation-induced plasticity-maraging steel -- Lamella -- Crack growth rate -- Crack closure -- High cycle fatigue; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2017.03.040
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: Lamella spacing increases with austenitization time, soften austenite hardness. The high level of austenite connectivity accelerates fatigue crack growth. The hierarchical laminated microstructure decelerates fatigue crack propagation. EBSD reveals that austenite in the vicinity of crack transformed to martenite. Abstract: The effect of austenitization time on the fatigue crack resistance of transformation-induced plasticity (TRIP)-maraging steel was investigated by observing the crack initiation site, propagation path and fracture surface. Our analyses show that austenitization for a longer time increases austenite/martensite lamella size and connectivity of austenite. Simultaneously, increasing lamella size leads to a reduction in austenite hardness; higher austenite connectivity accelerates crack propagation. In addition, remarkable roughness on the crack surface associated with the laminated structure was observed in both steels, which caused roughness-induced crack closure.