Comparison of surface integrity of Ti6Al4V titanium alloy manufactured by laser deposition and traditional method after end milling

Abstract

Ti alloy has been widely applied in aerospace due to its high strength, good corrosion resistance, and excellent high-temperature performances. The quality and usability of Ti alloy parts are closely related to surface integrity. In this study, a comparative analysis of the milling surface integrity between laser deposition manufacturing and traditional Ti6Al4V samples was conducted. End milling surfaces of additive and traditional Ti6Al4V samples were observed with an orthogonal experiment under different milling parameters from the perspectives of cutting force, surface morphology, surface roughness, subsurface damages, and microhardness. Results demonstrate that the additive Ti6Al4V sample has a slightly higher cutting force and surface roughness relative to traditional Ti6Al4V. This is related to the higher hardness and plasticity of the additive Ti6Al4V sample. There are unmelted powder particle defects on the milling surface of the additive Ti6Al4V sample and serious cracking defects on the subsurface of the additive Ti6Al4V sample. The microhardness of the work hardening layer and base of the additive Ti6Al4V sample is higher than that of traditional Ti6Al4V. Moreover, the additive Ti6Al4V sample presents higher work hardening and a larger depth of the hardening layer. These findings demonstrate that material properties and manufacturing processes can influence surface integrity significantly.