A COMPARISON OF DIFFERENT NUMERICAL APPROACHES FOR FSW WELDS OF API 5L - X80 STEEL

Abstract

This contribution offers a study for two numerical approaches of FSW joints for the API 5L-X80 steel. The first one, a pure thermal model, takes into consideration the preponderant frictional force of the tool being in contact with the workpiece. The second model is a computational fluid dynamic approach, which involves determining experimental values for physical constants and observing its influence in viscous dissipation and strain rates of the material. Temperature and thermal history from the FSW processing were recorded and analyzed. The acquired data was provided from two different heat input conditions. In cases of previewing tool or workpiece local temperature, the pure thermal model is a sufficient suitable approach. Conversely, the CFD model frequently requires huge amounts of information, regarding physical constants and experimental variables, becoming a delicate task for its construction. The pure thermal model was able to offer unequivocal temperature results without the need for large experimental data acquisition. This approach was considered to be finer employed when one aims to forecast temperatures in regions proximate to the welding line. The natural complexity associated with FSW processing suggests there are enormous quantities of experimental factors to be considered for the numerical modeling of high-temperature materials. Also, the CFD approach offers distinct results, which might be crucial for understanding the full aspects of experimental variables. A coupled numerical approach with both models is suggested to fully represent the thermophysical aspects of FSW processing.