Effect of bainite morphology on deformation compatibility of mesostructure in ferrite/bainite dual-phase steel: Mesostructure-based finite element analysis

Abstract

Ferrite/bainite (F/B) dual-phase pipeline steels with excellent balance of strength, ductility, and toughness have been broadly applied in oil and gas pipeline transmission. While, the deformation capacity of the steels is related to the grain size, volume fraction and morphology of the two phases. In this work, Representative volume elements (RVE) models based on real mesostructure and abstract model were built, and then the effect of the bainite morphology on the deformation compatibility of the mesostructure for F/B dual-phase steels were studied. Results show that the bainite morphology influence the strain localization within the mesostructure during the deformation process, as a result, the mesostructure with banded bainite possesses better deformation compatibility than the mesostructure with equiaxed bainite. Based on the abstract model, the aspect ratio of bainite significantly affects the deformation compatibility between the ferrite and bainite. The difference of plastic deformation (DPD) and the strain localization factor (SLF) rapidly decrease when the aspect ratio of bainite increases from 1 to 3.06. With the further increase of the aspect ratio of bainite, the DPD and SLF have a little change. The results will help to comprehend the deformation mechanism of the F/B dual-phase steels. Keywords: F/B dual-phase steel, Mesostructure, Deformation compatibility, Bainite morphology, FEM