Deformation-induced nontetragonality of martensite in carbon steels

With supersaturated carbon atoms ordering in the preferential octahedral sites of alpha-Fe lattice, the martensite formed in medium and high carbon steels exhibit a unique structural feature, tetragonality. In this letter, we reported anomalous nontetragonality of martensite in carbon steels by deforming quenched martensite, indicating that the disordering of interstitial carbon atoms in alpha-Fe lattice occurs under mechanical deformation. This order-disorder transition of interstitial carbon atoms in carbon steels provides solid experimental evidences of the prediction based on microscopic elasticity theory. (C) 2018 Elsevier B.V. All rights reserved.