Understanding Deformation on Machined Surfaces

The deformation history and state of machined surface in cutting of metals are characterized using high-speed image analysis, complemented by hardness, microstructure and texture measurements. Large surface strains are observed, due to the severe plastic deformation (SPD) intrinsic to chip formation. The deformation history and microstructure/texture of the chip and surface are found to be equivalent. The surface strain distribution is shown to scale with undeformed chip thickness and influenced by the rake angle. Based on the observations, and related prior work on process-microstructure-property correlations, a framework is suggested for controlling deformation levels, microstructure and texture on machined surfaces. The results offer scope also for validation of machining simulations and multi-scale modeling of machining.