Effect of bainite microstructure control on the deformation behavior of ferrite/bainite dual-phase steel

Abstract

Affected by the modes of bainite transformation, its microstructure, mechanical properties and its coordinated deformability with ferrite are changed. So that the deformation behavior and the mechanism of ferrite/bainite dual-phase steels are different at different deformation stages. In this study, SEM, EBSD and EMPA are used to investigate the effect of different intragranular and grain boundary bainite microstructures on the deformation behavior of ferrite/bainite dual-phase steels. The results show that: bainite transformation mode determines the morphology of carbide in the bainite, which in turn affects the bainite hardness. The bainite with high hardness can hinder the expansion and merging of microcracks, delay the occurrence of plastic instability in experimental steels, and improve the deformation property of the experimental steel at the later stage of tensile deformation. The bainite with low hardness has good coordination of deformation with the ferrite matrix, and the low-angle grain boundaries are conducive to the diffusion of stress to ferrite, which improves the deformation property of the experimental steel at the initial stage of tensile deformation. The bainite microstructure obtained through microstructure control has the advantages of the above two types of bainite and shows good deformation properties throughout the deformation process.