Specification of Shear Zone Characteristics in Achieving Desired Residual Stress Profile

Surface integrity of a machined component in meeting the demands of a specific application requirement is defined by several characteristics. The residual stress profile at the surface and sub-surface of the workpiece is often one of these characteristics as it carries a direct effect on the fatigue life of a machined component. Machined residual stress is difficult to predict since it is governed by less than predictable high stresses, temperature gradients, and phase transformation occurring during the cutting process. A significant amount of effort have been dedicated by researchers to predict residual stress in a workpiece using analytical, experimental, and numerical modeling methods. Nonetheless, no method is available that could express the cutting process parameters and tool geometry parameters as functions of machined residual stress profile to allow process planning in achieving desired residual stress profile. This paper presents a physics-based approach to predict the shear zone characteristics during an orthogonal cutting operation. Using machined residual stress requirement at the surface as an input, information such as the shear angle, the shear stress in the shear zone, the depth of cut and consequently the cutting forces are obtained by inverse calculations procedure based on the rolling/sliding contact theory, the McDowell hybrid residual stress algorithm, and the specific cutting energy. This work constitutes a basis for further design and optimization of process and tool geometry parameters in achieving a specified residual stress profile. Experimental data are presented to validate the developed model.