Rapid acquisition of digital fingerprints of Ti-6Al-4V macrotexture from machining force measurement data

Titanium alloys display anisotropic deformation properties due to the hexagonal close-packed (hcp) crystal structure of the alpha-phase. When subjected to localised deformation during machining, this behaviour influences fluctuations in the cutting force response of the material as the tool encounters grains of different orientations. In this research, cutting force signals acquired during face turning of Ti-6Al-4V possessing a lamellar alpha colony structure have been spatially mapped demonstrating the ability to identify microstructural features such as prior beta grain boundaries, grain boundary alpha, and alpha colonies. Measured cutting forces have been correlated to texture using orientation information acquired from large area EBSD analysis. A relationship between the misalignment of the crystallographic a slip vector with respect to the cutting direction and the passive cutting force response has been established, demonstrating a rise in cutting forces as this misalignment is increased. This novel approach to in-process materials evaluation offers manufacturers the potential of a powerful digital quality assurance tool, with the results presented here demonstrating the possibility for rapid characterisation of entire component surfaces, revealing microstructural features, and inferring the crystallographic orientation of macrotextured regions in Ti-6Al-4V.