Reverse Transformation from Martensite into Austenite in a Dual Phase Steel




Abstract: A commercial dual phase steel was heat treated to obtain a fully martensitic matrix as the initial condition. Subsequently, different cycles of intercritical reversion led to the development of microstructures composed by laths of martensite, intercritical ferrite and retained austenite. Heat treatments were conducted on a quenching dilatometer. Samples were characterized by SEM-FEG, EBSD, X Ray Diffraction and sub size tensile tests. It was found that the higher the intercritical reversion temperature, the smaller the fraction of intercritical ferrite. On the other hand, the transformation temperature significantly influenced the stability of the retained austenite. The highest fraction of retained austenite was obtained when the transformation occurred slightly above the Ac1 temperature. A double intercritical reversion cycle promoted the diffusion of C and Mn to the reversed austenite making it more stable upon cooling to room temperature, leading to a better combination of strength and ductility.

Authors: Dany Michell Andrade Centeno and Hélio Goldenstein

Keywords: Retained austenite, annealing, austenite reverted

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3 pages


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