The hot rolled duplex laminated steel presenting both high strength and high toughness

Abstract

In this study, a new steel with the chemical composition of Fe-0.15C-5Mn-3Al (wt-%) was designed. Its microstructure and mechanical properties were examined by optical microscopy, scanning electron microscopy and mechanical tests. It was found that hot rolling in the dual phase region of ferrite and austenite at high temperature resulted in micro-laminated dual phase microstructure. An excellent combination of high strength (∼1200MPa) and ultrahigh impact toughness (∼400J) of the micro-laminated dual phase steel was obtained. Based on the measurement of the phase volume fraction and the analysis of the fractography, it was shown that the high strength was mainly dependent on the high martensite volume fraction, while the ultrahigh impact toughness was attributed to the micro-laminated microstructure.