FEM prediction of dislocation density and grain size evolution in high-speed machining of Al6061-T6 alloy using microgrooved cutting tools

Abstract

In this paper, the commercial FEM software package Abaqus is used to investigate the evolution of dislocation density and grain size in orthogonal cutting of Al6061-T6 alloy using microgrooved cutting tools. Microgrooves are designed and fabricated on the rake face of cemented carbide (WC/Co) cutting inserts. A coupled Eulerian-Lagrangian (CEL) finite-element model is developed based on Abaqus to solve the evolution of the dislocation density and grain size simultaneously. This validated CEL FEM model is then utilized to investigate the effects of microgrooved cutting tools on the evolution of dislocation density and grain size in orthogonal cutting of Al6061-T6 alloy. The effects of microgroove width and microgroove convex width are examined and assessed in terms of cutting force, chip morphology, dislocation density, and grain size. It is found that this CEL FEM model can capture the essential features of orthogonal cutting of Al6061-T6 alloy using microgrooved cutting tools. It is also concluded that microgrooved cutting tools can increase the cutting force in machining Al6061-T6 Alloys, which is contrary to the conclusion obtained for machining AISI 1045 in previous research. The reason for this might be due to the fact that Al6061-T6 alloy has relatively low Young’s modulus and consequently, it is much easier to fill the microgrooves within the tool-chip interface, making the microgrooves serve as microcutters instead of breaking the intimate contact between the chip and the rake face of the tool. It is also concluded that microgroove width and convex width can effectively change the dislocation density profiles and grain size profiles along the depth from the machined surface and the tool-chip interface, respectively, making it possible to alter the surface integrity of the machined surface based on needs.