Microstructural mechanisms of fatigue crack non-propagation in TRIP-maraging steels. (August 2018)

• 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 113(2018)
• Page Start: 126
• Page End: 136
• Publication Date: 2018-08
• Subjects: TRIP-maraging steel -- Laminated structure -- Fatigue limit -- Crack closure -- Non-propagating fatigue crack; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2018.04.013
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: Fatigue crack non-propagation behavior of laminated TRIP-maraging steels was clarified. KAM map verified that austenite-related boundaries are prone to fatigue damage. Fatigue crack growth is decelerated by deformation-induced martensitic transformation. Crack roughness contributes to the non-propagating fatigue crack. Fatigue crack non-propagation behavior depends on lamellar alignment. Abstract: In contrast to conventional martensitic steels, transformation-induced plasticity (TRIP)-maraging steels exhibit exceptional high ductility without sacrificing strength and excellent fatigue property owing to the retained austenite/maraging martensite laminated structure. In this study, TRIP-maraging steel (Fe-9Mn-3Ni-1.4Al-0.01C, wt.%) with fine grained austenite was used to investigate the mechanism of high cycle fatigue resistance. Our analyses revealed that soft austenite region acts as a preferential crack propagation path, but the plastic deformation during crack opening involves martensitic transformation, resisting subsequent crack growth via transformation-induced local hardening or crack closure. Moreover, crack growth along the laminates and across the block boundary forms a zigzag crack path, which would act as roughness-induced crack closure. The combined effect of these factors plays an important role in resisting fatigue crack growth at high cycle fatigue.