Modeling of Heat Transfer Coefficient of Oxide Scale in Hot Forging

In hot forging processes, an accurate prediction of temperature distribution is important because it affects not only the forging load but also the material flow itself and the distribution of material properties in forged parts. An oxide scale will form at the surface of steel when heated to high temperature. The heat flows through this scale layer from the high temperature material to the dies or air, thus for an accurate prediction of temperature distribution, a precise evaluation of the heat transfer coefficient of scales is required. In actual hot forging processes, the thickness and composition of oxide scales will vary with the composition of steel, heating temperature and time, or the atmosphere. In this study, the heat transfer coefficients of oxide scales, formed on the surface of medium carbon steel with various heating temperature and heating time, are measured. A model of heat transfer coefficients is obtained as a function of the thickness of each oxide contents layer and the contact pressure.