CoCrMo cellular structures made by Electron Beam Melting studied by local tomography and finite element modelling

• CoCrMo samples fabricated by Electron Beam Melting (EBM) process are considered.
• X-ray Computed Tomography is used to observe the structure of the sample.
• The mechanical properties are tested thanks to an in situ test in the tomograph.
• A finite element model is developed to model the mechanical behaviour.

The work focuses on the structural and mechanical characterization of Co-Cr-Mo cellular samples with cubic pore structure made by Electron Beam Melting (EBM). X-ray tomography was used to characterize the architecture of the sample. High resolution images were also obtained thanks to local tomography in which the specimen is placed close to the X-ray source. These images enabled to observe some defects due to the fabrication process: small pores in the solid phase, partially melted particles attached to the surface. Then, in situ compression tests were performed in the tomograph. The images of the deformed sample show a progressive buckling of the vertical struts leading to final fracture. The deformation initiated where the defects were present in the strut i.e. in regions with reduced local thickness. The finite element modelling confirmed the high stress concentrations of these weak points leading to the fracture of the sample.