On the role of the Thermal Contact Conductance during the Friction Stir Welding of an AA5754-H111 butt joint

In Friction Stir Welding (FSW), the clamping conditions affect the mechanical and metallurgical properties of friction stir welded joints. Due to the involved forces is necessary rigidly lock the two sheets by means of an appropriate rigid fixing system on the underlying support plate. The temperature distribution and the trend of the heat flow is required to predict the properties of the joints and to optimize the welding parameters. Moreover, the evaluation of the Thermal Contact Conductance (TCC) is necessary to predict the heat fraction that is channeled to the tool, the one toward the sheet metal and to the clamping system. A three-dimensional finite element model (FEM) was developed to predict the evolution of the thermal flux in an FS-welded joint of aluminum alloy, considering the presence of the backing plate and the clamping system. The Thermal Contact Conductance (TCC) was measured under different temperature and pressure conditions. Experiments on a welding on 6 mm of AA5754 H111 were also carried out, to compare the model with the experimental results. (C) 2016 Elsevier Ltd. All rights reserved.