Role of stress-assisted martensite in the design of strong ultrafine-grained duplex steels. (1st January 2015)

• Record Type: Journal Article
• Authors: Yen, Hung-Wei; Ooi, Steve Woei; Eizadjou, Mehdi; Breen, Andrew; Huang, Ching-Yuan; Bhadeshia, H.K.D.H.; Ringer, Simon P.
• Is Part Of: Acta materialia. Volume 82(2015)
• Page Start: 100
• Page End: 114
• Publication Date: 2015-01-01
• Subjects: Transformation-induced plasticity -- Duplex steel -- Atom probe microscopy -- Transmission Kikuchi diffraction; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2014.09.017
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: This work explains the occurrence of transformation-induced plasticity via stress-assisted martensite, when designing ultrafine-grained duplex steels. It is found that, when the austenite is reduced to a fine scale of about 300 nm, the initial deformation-induced microstructure can be dominated by parallel lamellae of ε martensite or mechanical twinning, which cannot efficiently provide nucleation sites for strain-induced martensite. Hence, α′ martensite nucleation occurs independently by a stress-assisted process that enhances transformation-induced plasticity in ultrafine-grained austenite. This metallurgical principle was validated experimentally by using a combination of transmission Kikuchi diffraction mapping, transmission electron microscopy and atom probe microscopy, and demonstrated theoretically by the thermodynamics model of stress-assisted martensite.