A physics-based model of residual stress in minimum quantity lubrication (MQL) machining is presented. The stresses resulting from thermal and mechanical loading in the MQL machining process are coupled into an incremental thermal-elastic-plastic model for predicting the final resultant residual stress in the machined workpiece. Comparative analysis is made between the stresses produced by the thermal load and mechanical load in the machining process. Results manifest that for the surface of the machined workpiece, the stress produced by thermal load is on par with the contact stress produced by mechanical load in the magnitude. With the increase of depth into the workpiece, the stress produced by mechanical load is dominant of the total stresses. The rationale demonstrates that thermal load is prone to generate the tensile residual stress at the surface of the machined workpiece, while the mechanical load is prone to generate the compressive residual stress at the surface of the machined workpiece. Finally, the residual stress prediction model is verified by orthogonal cutting of AISI 4130 alloy steel.
