Study on deformation restraining of metal structure fabricated by selective laser melting

This paper pertains to the thermal and strain behaviour in laser consolidation of metal powders by additive manufacturing. The temperature and strain induced in the substrate during the laser consolidation process were theoretically estimated by the thermal-structure interactive analysis with two-dimensional finite element method, and experimentally evaluated in order to investigate the influence of thermophysical and mechanical properties on the resistance to thermal deformation in the consolidated structure. Additionally, the effects of different ferrous-based materials on the deformation were also investigated. The results reveal that the deformation of the consolidated structure was mainly caused by the thermal expansion and shrinkage induced by the laser beam which was repeatedly irradiated to the deposited powder. The deformation direction varied depending upon the temperature gradient which was induced inside the structure and stiffness of the consolidated structure which was added on the substrate. The analytical results obtained coincided well with the experimental results. The coefficient of thermal expansion was one of the most effective factors in restraining the thermal deformation, and the thermal deformation was reduced by combining the materials in which the coefficient of linear expansion was similar. In addition, the deformation was minimized by adjusting the temperature gradient induced by the laser beam irradiation.