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Role of stress-assisted martensite in the design of strong ultrafine-grained duplex steels


Type

Article

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Authors

Yen, HW 
Ooi, SW 
Eizadjou, M 
Breen, A 
Huang, CY 

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 epsilon martensite or mechanical twinning, which cannot efficiently provide nucleation sites for strain-induced martensite. Hence, alpha 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.

Description

Keywords

Transformation-induced plasticity, Duplex steel, Atom probe microscopy, Transmission Kikuchi diffraction

Journal Title

Acta Materialia

Conference Name

Journal ISSN

1359-6454
1873-2453

Volume Title

82

Publisher

Elsevier BV
Sponsorship
The authors acknowledge the facilities, and the scientific and technical assistance of the Australian Microscopy & Microanalysis Research Facility (ammrf.org.au) node at Sydney Microscopy & Microanalysis, at the University of Sydney.