Comparative analysis of heat generation in friction welding of steel bars

For the first time a comparative thermal analysis of the friction welding process using various heat generation models is presented. The heat-generation rate in orbital friction welding of steel bars is analyzed using four different methods; constant Coulomb friction, sliding-sticking friction, the experimentally measured power data and an inverse heat conduction approach. A comparison between the calculated temperature profiles and the experimental data shows that the inverse heat conduction approach predicts the heat-generation rate accurately, whereas the constant friction coefficient approach leads to the most inaccurate temperature profile. Moreover, a three-dimensional thermornechanical finite element (FE) analysis based on the calculated heat input data and the experimental axial shortening rate demonstrates that the process can be analyzed in a one-dimensional domain due to the short frictional heating cycle and the uniform heat-generation rate across the interface. The FE analysis also indicates that the heat-generation rate due to the plastic deformation in the workpiece away from the interface is negligible compared to the heat-generation rate by friction. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.