Evolution of Poisson's Ratio in the Tension Process of Low-Carbon Hot-Rolled Steel with Discontinuous Yielding

Low-carbon hot-rolled steel generally undergoes a deformation process composed of four phases, i.e., elastic deformation, discontinuous yielding, work hardening, and macroscopic plastic-strain localization in a tension test. The evolution of the Poisson's ratio in terms of the average Poisson's ratio and the local Poisson's ratio in the deformation process from the non-load state to the onset point of specimen necking was investigated. The main results are as follows: (1) the average Poisson's ratio cannot accurately represent the local Poisson's ratio in the discontinuous-yielding phase; (2) the Poisson's ratio varied significantly within a plastic band in the discontinuous-yielding phase, and the maximum Poisson's ratio was reached within the plastic band; and (3) the strain rate greatly increased the Poisson's ratio.