The critical strain, after which the flow stress almost remains constant, was investigated in the dynamic material properties test of Al7050-T7451. So, the strain cut-off value was introduced into the power-law material model to prevent the large extrapolation errors at strains that were higher than tested. Turning experiments considering the different rake angles, feed rates, and cutting speeds were performed. The turning forces and chip thickness were measured. Turning processes with different strain cut-off values were simulated by the aid of finite element method software AdvantEdge. The simulated turning forces and chip thickness were extracted. The strain cut-off value was determined by the comparison of experimental and simulated results, 0.3 in this case. Simulated results showed good agreement with the experimental results.