This work investigates the influence of the Friction Stir Welding (FSW) parameters on the mechanical properties AA 2198 T3 welds. For this purpose, a full-factorial experimental design was conducted. The observed responses are ultimate tensile strength (UTS) and yield strength (YS). The factors under investigation are tool rotational speed (N) and welding feed (Va). In order to estimate the influence of the heat transfer transient phase on the mechanical properties of the weld, besides these classical welding parameters, a position parameter defining the relative distance of the specimens from the welding run-in and run-out is considered. Analysis of variance (ANOVA), main effect plot and desirability function technique were used to determine the significant parameters and set the optimal level for each parameter. A regression equation was derived to predict each output characteristic