Machining accuracy can be compromised by elastic workpiece deformation and subsurface residual stress introduction during cutting. In order to anticipate the impact of cutting forces and surface integrity evolutions on finished surface and its geometrical errors, it is necessary to better understand the influence of cutting conditions and tool wear. In this study, machinability of Inconel 718 using a round carbide tool in finish turning conditions is assessed. Cutting forces evolution during tool life are analysed and accompanied by advanced investigations of cutting phenomena. An original mechanistic cutting force model is developed, identified and tested. It includes the effect of tool wear over time in its local formulation. This model allows predicting cutting forces evolution along tool pass for a wide range of finishing cutting conditions. Furthermore, a thorough analysis of residual stress profiles at different tool wear levels is led. It features quantitative results for fresh and worn tools. A study on the influence of cutting parameters and tool wear on residual stress profiles in the machining affected zone is highlighted.

The predictability of manufacturing process simulation is highly dependent on the accuracy of the constitutive model to describe the mechanical behavior of the work material. The model should consider the most relevant parameters affecting this behavior. In this study, a constitutive model for Ti6Al4V titanium alloy is proposed that considers both material plasticity and damage. It includes the effects of strain hardening, strain-rate and the state of stress to represent the mechanical behavior of Ti6Al4V titanium alloy in metal cutting simulation. To generate states of stress and strain rates representative of this process, mechanical tests were performed using a specific experimental setup. This included a specimen geometry designed to generate different states of stress, as well as a digital image correlation technique to obtain the strains during the mechanical tests. For the determination of the coefficients of the constitutive model, the yield stress and fracture locus obtained from these tests were used in an optimization-based procedure. To verify the accuracy of the proposed constitutive model to represent the mechanical behavior of the Ti6Al4V alloy under different states of stress, force-displacement curves obtained using this model and the Johnson-Cook model are compared with the curves obtained experimentally.

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