Although there have been several flow models and heat source models proposed in the refereed literature of Friction Stir Welding, there is a shortage of real world thermal data against which to validate the proposed models.   This is largely due to the “contained” nature of the actual Friction Stir Welding process.  The heat sources of deformation are located within the base metal being welded and underneath the rotating tool shoulder.     Thermal data in the reported literature is usually coincidental to the primary goal of the experimental design and non-symmetrical.

An internal thermal mapping protocol/device has been developed which allows for symmetrical mapping of the thermal fields developed by the tool as it passes through the material being welded.   This symmetrical mapping clearly documents the “asymmetrical” nature of the heat sources within the friction stir welding process.   One side of the pin is always without fail hotter than the other, with similar results for the two sides of the shoulder.   The various models in the literature are compared against these results.  A successful predictive model will facilitate tool optimization and welding schedules as well as the mechanical properties of the weld.