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arXiv · 1401.5824

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

Hung-Wei Yen·Steve Woei Ooi·Mehdi Eizadjou·Andrew Breen·Ching-Yuan Huang·H. K. D. H. Bhadeshia·Simon P. Ringer
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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.

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Hung-Wei Yen, Steve Woei Ooi, Mehdi Eizadjou, Andrew Breen, Ching-Yuan Huang, H. K. D. H. Bhadeshia, Simon P. Ringer. 2014-01-22. Role of stress-assisted martensite in the design of strong ultrafine-grained duplex steels. https://doi.org/10.1016/j.actamat.2014.09.017

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