Machined titanium components, such as medical prosthesis, require the greatest reliability, which is determined by process induced surface integrity. However, surface integrity of milled titanium components easily deteriorates due to the poor machinability of titanium alloys and cyclic chip loading during milling. Milling induced surface integrity, including anisotropic surface roughness, residual stress, surface microstructure alterations and microhardness, has received little attention. In the present study, a series of end milling experiments were conducted to comprehensively characterise surface integrity at various milling conditions of titanium alloy Ti–6Al–4V with TiAlN coated carbide cutting tools. The experiments were carried out under dry cutting conditions. For a range of cutting speeds, feeds and depths of cut, analyses of machined surface roughness, residual stress, microhardness and the microstructural observations were carried out. The present work aims to evaluate the influence of different milling conditions on workpiece surface integrity.

Titanium alloys have been widely used in industries, especially aerospace, energy and medical industries, due to their good mechanical and chemical properties. However, titanium alloys are typically difficult-to-cut materials. Milling induced surface integrity, including anisotropic surface roughness, residual stress, surface microstructure alterations and microhardness, has received little attention. This work investigated the effect of machining conditions, especially the federate, on surface integrity of workpiece of Ti-6Al-4V alloy machined using high speed ball end milling process. The experimental tests were performed at various cutting parameters and carried out in dry conditions on a vertical five-axis CNC milling machine, using a coated carbide tool. Surface finish was studied based on 3D topographic maps and microhardness depth profiles beneath the machined surface. Microstructure of the sub-machined surface was observed using an optical microscope in order to investigate the metallurgical deformation. X-ray diffraction analysis is performed to obtain the residual stress distribution beneath the surface.