Prediction of static strain hardening progress from cementite morphology in hypo-eutectoid carbon steel

A numerical method is proposed to predict the progress of static strain aging from the cementite morphology in hypo-eutectoid steel in the aging temperature interval from about 473 to 573 K. It is assumed in the approach that strain aging is dominated by the dislocation locking of carbon atoms released during the decomposition of cementite, and that the steel becomes hard in proportion to the amount of diffused carbon atoms in ferrite. Based on scanning electron microscopy images, a finite element mesh was composed, and numerical analyses were carried out in a similar way to heat transfer analysis. As a result, the transfer coefficient of carbon atoms in the ferrite–cementite boundary was estimated compared with experimental results. Moreover, the influence of grain size on strain aging was obtained using the proposed numerical analysis.