Measurement and Analysis of Heat Transfer and Friction During Hot Forging

Abstract

An investigation of heat transfer and friction during hot forging has been performed using experimental and analytical techniques. The interface heat transfer coefficient was measured in experiments in which two flat H-13 tool steel dies were heated to different initial temperatures and brought together under varying pressure levels, or the two dies were heated to the same temperature and used to upset aluminum alloy 2024-0 rings under both isothermal as well as nonisothermal conditions. The coupling between heat transfer and friction during hot forging has been studied by analysis of data from the ring experiments and the generation of heat transfer coefficient and friction shear factor calibration curves derived from finite element simulations. By this means, the effects of forging pressure, deformation rate, and lubrication on the heat transfer coefficient and the friction shear factor were established. It was shown that, for the geometry studied, the value of the friction shear factor is independent of the heat transfer coefficient and vice versa, at least to a first order.