Mechanical behaviour of porous metals fabricated by low-power selective laser melting

In selective laser melting (SLM) metal powder is completely melted using a high-power laser beam of 200-400 W to form metallic parts which are almost completely dense and do not require post processing. To reduce the effective Young's modulus of fabricated parts by SLM to that of human bone, strut structures with interconnected pores of mm size are usually adopted for bone implants. In contrast, parts fabricated by SLM or selective laser sintering (SLS) under laser power below about 50 W are not fully dense and contain micropores, resulting in the reduction of the part’s Young's modulus. However, low-power laser SLM/SLS techniques have yet to be extensively studied. In this study, we examine the densities, effective Young's modulus, and metal structure of parts fabricated by low laser power SLM from pure Ti powder under various experimental conditions. The effective Young’s moduli of as-sintered cubic specimens were a few GPa independent of energy density. After applying normal loads, the effective Young’s moduli increased in various rates, according to energy density. At a normal load of 10kN, the effective Young’s moduli were divided into three groups, 10, 40 and 100 GPa. The relative density ranged from 50 to 75% and cluster size from 70 to 330 μm depending on the energy density.