Dual-phase steels are attractive because of their good combination of strength and ductility. However, an increase in the martensite content will decrease the steel's machinability significantly. Therefore, optimum cutting parameters in the machining of suca materials should be determined. In this paper, the machinability of a low-alloy steel having various martensite volume fractions was investigated. The four groups of samples, three of which were intercritically annealed at three different temperatures and one of which was normalized, were used. Then, the machining experiments were carried out using a face-milling operation with two different tools. After that, the flank wear on the tools with respect to the chip-volume or flank-wear limit was determined for each case. Next, the surface roughness of the samples was measured. Finally, the wear behavior of the tools was examined with a scanning electron microscope (SEM). The experimental results indicated that the flank wear of the tools increased dramatically with the increasing martensite content of the dual-phase steels.