Optimal laser scanning parameters to densify commercial-purity aluminum, fabricated using selective laser melting (SLM), were studied using an SLM machine equipped with a 400 W Yb fiber laser. The SLM samples with a relative density of 99.7% were obtained. The microstructures and the thermal and mechanical properties of the dense SLM samples fabricated using the optimal laser scanning parameters were investigated. The as-fabricated SLM samples had granular microstructures of aluminum, silicon, and/or iron oxides dispersed finely (～0.3 μm) due to the rapid solidification by laser irradiation. The mechanical properties were thus confirmed to be excellent (ultimate tensile strength: 110 MPa, proof stress: 90 MPa, breaking elongation: 30%). The thermal conductivity of the SLM sample was approximately 200 W/m·K, which was slightly inferior to that of the wrought commercial-purity aluminum (230 W/m·K). The effect of annealing on the properties of the SLM samples were also investigated. The thermal conductivity of the SLM sample annealed at 450℃ for 10 minutes increased to the same value as that of the wrought commercial-purity aluminum, although both the proof stress and breaking elongation were slightly decreased.

This Paper was Originally Published in Japanese in J. JILM 66 (2016) 167–173.