Selective laser melting of high strength Al-Cu-Mg alloys: Processing, microstructure and mechanical properties

The interest for a wider range of usable materials for the technology of selective laser melting (SLM) is growing. In this work, the manufacturing of wrought Al-Cu-Mg parts using SLM technology was systematically investigated. The effect of processing parameters on the density of the deposited Al-Cu-Mg samples was studied. It shows that the laser energy density plays a significant role in the densification behavior of the Al-Cu-Mg powder during the SLM process. The laser energy density value of 340 J/mm3 is found to be the threshold, above which high density samples (99.8%) without imperfections and microcracks can be obtained. The SLMed Al-Cu-Mg part presents a unique layer-wise feature which consisted of an extremely fine supersaturated cellular-dendrites structure. The ultimate tensile strength of 402 MPa and the yield strength of 276 MPa are achieved for the SLMed Al-Cu-Mg part. The combination of grain refinement and solid solution strengthening mechanisms during SLM process are proposed to explain the high mechanical strength.