Modeling of cementite formation in extra and ultra low carbon steels

The solute carbon content in ferrite is a very important factor to obtain good formability in interstitial free steels. Although most of carbons are consumed by formation of grain boundary cementite during coiling after hot-rolling, the carbon content of final state after coiling is much more than that of equilibrium. In this study, the effects of total carbon content and cooling rate on grain boundary cementite formation are modeled by classical nucleation and growth. As results of simulation, the reason of sluggish kinetics of grain boundary cementite is a lateral growth of thickening toward ferrite grain interior. Also, the carbon content in ferrite increases as total carbon content increase, it is a good agreement of trend with experimental results from literatures.