Investigation of mechanical properties of Ti-6Al-4V alloy produced by additive manufacturing

Ti-6Al-4V parts used in aerospace, defence, automotive and biomedical industries can be produced in a complex shape by maintaining the mechanical properties by electron beam melting (EBM) method which is one of the powder based additive manufacturing methods with the lowest amount of waste material. In this study, mechanical properties of Ti-6Al-4V alloys produced by using Arcam Q20 Plus EBM machine in different dimensions in horizontal and vertical directions were examined. Density and surface roughness of the samples produced by EBM method were measured and it was shown that density decreased, and the roughness value increased as the production size decreased. Manufactured samples were subjected to tensile tests in standard dimensions (diameter 6 mm). Regardless of the production direction and production position, the tensile properties of the samples produced in block sizes are higher than those of offset and standard sizes. The pore and brittle fracture zones on the fracture surfaces examined after the tensile test confirm the obtained tensile test results. The microhardness test applied to the samples showed that the edge region of the part had higher hardness than the center, and the center of the block samples had a lower hardness than the offset and standard dimensions. After metallographic examination applied to the samples, Ti-6Al-4V samples are dominated by the α grain boundary and the lamellar α + β microstructure due to slow cooling after production. It was observed that the thickness of the α plates in the edge region was thinner than the central regions and the highest α plate thickness (1.7 μm) was obtained in the center of block sample as a support for the hardness values of the samples. In addition, Ti-6Al-4V alloy powder used in EBM method was characterized before and after production. After the production with EBM, it was determined that the average size of the powders remaining under the mesh decreased and only these alloy powders can be used in the next production.