For several decades, the slip-line theory has been used to model and explain metal cutting operations. The previous slip-line models were mostly developed for continuous chip formation. However, the authors of this paper recently developed and analyzed a slip-line model for serrated chip formation. In that model, Oxley’s predictive machining theory was employed. In the current study, the previously developed slip-line model was modified for machining of Ti6Al4V alloy by using Johnson-Cook model. To validate the modified slip-line model, orthogonal turning experiments were conducted under dry condition at three different cutting speeds and a constant undeformed chip thickness, and the results were compared with predicted results from the extended slip-line model. This analysis shows good correlations between experiments and predictions. Additionally, the position of stagnation point, tool-chip contact length, chip up-curl radius, thickness of primary shear zone, flow stress, average shear strain and average shear strain-rate were also determined.