Thermo-Mechanical Modelling of Dissimilar Aluminum-Steel Friction Stir Welds

Friction stir welding (FSW) is a solid state joining process capable of welding high melting temperature materials and dissimilar alloys. Its ability to produce sound welds with excellent properties in dissimilar joints has gained the attention of industry and researchers all around the word. This work aims to present a thermo-mechanical model of the FSW process of a dissimilar aluminum-steel joint in order to evaluate the thermal characteristics of the welding zone. The model results are helpful to better understand the properties of the final welds since they are directly affected by the thermal history they were exposed to. The model consists of a finite element analysis where the heat generation from the frictional contact and the plastic deformation is modeled as a boundary heat flux at the tool/workpiece interface. To validate the simulations, 2.0 mm thick aluminum alloy 6063-T5 and AISI 1020 steel sheets were friction stir welded at 300 rpm and 150 mm.min^-1. During welding, the normal and transversal forces, and the torque were recorded. The thermal history was also recorded using thermocouples positioned at different distances from the joint centerline. This information was used to compare the results obtained with the finite element simulation. The simulation results are in good agreement with the measured temperatures showing a similar temperature profile and it is also capable of estimating the temperature distribution across the joint.