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The paper proposes the prediction of the fatigue strength of additive manufactured Ti6Al4V titanium alloy machined under flood and cryogenic cooling conditions, making use of the approach based on linear elastic fracture mechanics that was used for the first time in the context of such process chains. The role of the machining-generated surface texture, hardening, microstructural characteristics and residual stresses states is discussed in detail, giving new insights about the correlation between surface integrity and fatigue strength when addressing defective metal alloys, as those fabricated through AM. [ABSTRACT FROM AUTHOR]

This work investigates the machinability characteristics of additively manufactured Ti6Al4V titanium alloy workpieces in finishing machining using ball end mills on 45° inclined surfaces. The surface finish results were compared with the ones from ball end milling trials on wrought Ti6Al4V samples using the same cutting conditions. Optical profilometry and scanning electron microscope imaging were used to compare the different surface texture and quality of the two alloys, as well as the chip morphology, with the aim of finding a correlation between the surface finish obtained at varying cutting parameters and the Ti6Al4V peculiar microstructure induced by the additive manufacturing process. The results showed that the additively manufactured alloy allowed for a better surface quality respect to the wrought one. This was attributed to the interactions of the ball mill cutting edge with the α phase colonies of such alloy, which may favor the material removal by locally lowering the material resistance to cutting. [ABSTRACT FROM AUTHOR]

Final machining steps are commonly requested on parts obtained via additive manufacturing to ensure the required surface finish and geometrical tolerances. When machining additive manufactured workpieces, their typical microstructural anisotropy is rarely taken into consideration. In this work, the influence of the build-up orientation of Ti6Al4V parts obtained via laser powder bed fusion on machinability is studied. Ti6Al4V blocks with horizontal and vertical development were additively manufactured and then milled. Tool wear progression was monitored and its effect on surface quality investigated. The cutting tool that machined the horizontally oriented sample showed a tool life 66% higher than the one that machined the vertically oriented one. This study demonstrates the strong correlation between the build-up orientation of additive manufactured components and their machining response. [ABSTRACT FROM AUTHOR]