A coupled thermal-mechanical model of plane-strain orthogonal metal cutting with continuous chip formation is developed to investigate the residual stresses in the finished workpiece. Deformation of the workpiece material is treated as elastic-viscoplastic with isotropic strain hardening, and the numerical solution accounts for coupling between plastic deformation and the temperature field, including treatment of temperature-dependent material properties. Automatic continuous remeshing and adaptive meshing technique are employed to achieve chip separation at the tool tip region and a satisfactory solution. The finite element model is well validated by comparing values of the predicted cutting forces and residual stresses with experimental results. Based on the established finite element model, the effect of rounded cutting edge radius on residual stress distribution is analyzed. The results show that altered cutting edge radius clearly produced significant changes in residual stresses. The maximum tensile residual stress and its penetration depth decrease as the cutting edge radius increases.