Influence of Interstitials on Material Properties of Ti6Al4V Produced with Electron Beam Melting

Arcam has developed the Electron Beam Melting (EBM) technology specifically for cost-efficient production of medical implants. The implants are manufactured layer-by-layer from metal powder, melted by a powerful electron beam. Each layer is melted to the exact geometry defined by the 3D CAD model. The implants are produced in vacuum at elevated temperatures, resulting in stress-relieved parts with material properties better than cast and comparable to wrought material. Solid and porous sections of the implant are built in the same process step, eliminating the need for expensive secondary processes to apply other porous materials. EBM is used for series production of acetabular shells and other orthopedic implants since 2007.

It is well known that the mechanical properties of Ti6Al4V are affected by the amount of interstitials. From an EBM-specific database containing chemical and mechanical data sets, the influence of interstitials such as iron, oxygen and nitrogen has been extracted with multivariable regression. The results reveal a process with small variations and predictable mechanical properties.  Just as for wrought Ti6Al4V, the tensile strength increases with increasing interstitial concentration.