Improvement of strength and toughness for hot rolled low-carbon bainitic steel via grain refinement and crystallographic texture

Low-carbon bainitic steel with effective grain size of similar to 2.0 tm and strong < 110 > //RD (rolling direction) transformation texture was obtained by adopting ultra fast cooling following non-recrystallization rolling. The steel exhibited higher tensile strength of 840 MPa and lower ductile-to-brittle transition temperature of 106 C in comparison with the steel that had no distinct texture with effective grain size of 4.5 um. High intensity of {110} planes normal to the rolling direction were formed as a result of the strong {114} Q231 < 110 > transformation texture and effectively inhibited the main crack propagation by ductile fracture mechanism. The existing {100} planes parallel to the rolling plane led to the impact fracture delamination at -20 similar to -100 degrees C, which improved the low temperature toughness. (C) 2016 Elsevier B.V. All rights reserved.