The Grain-Size-Dependence of Flow Stress in Mild Steel

Abstract

AbstractTensile tests have been made on mild-steel specimens with a range of grain sizes. Suppression of the yield point for the purpose of observing the early stages of work-hardening was accomplished by decarburizing in wet hydrogen or by quenching from 700°C. Analysis of the results indicates that there are two regions of work-hardening, which operate below and above 10% elongation, respectively. During the first stage, where work-hardening is parabolic, the rate of hardening varied with grain size. This was interpreted in the light of recent experimental observations relating flow stress and dislocation density, enabling an equation to be written that describes the flow stress in terms of grain size and plastic strain for the first 10% of elongation.