Ductile damage assessment of Ti6Al4V, 17-4PH and AlSi10Mg for additive manufacturing

A great research effort has been spent during the latest years in the characterization of additive manufacturing (AM) alloys, mostly focused on the analysis of microstructure and on the assessment of mechanical strength, especially under high cycle fatigue loads. Post-process treatments have been also investigated, as methods to further improve the AM materials performance. On the contrary, still fewer data are available on AM materials ultimate static strength. The present paper is intended to present a comprehensive experimental and numerical static characterization of Ti6Al4V, 17-4PH, and AlSi10Mg alloys processed via selective laser melting. A dedicated set of specimen geometries was devised to induce desired multiaxial stress state, and experiments were carried out both on as built and machined AM samples. The results were employed to identify the constitutive behavior of the materials and to calibrate four different ductile damage models. The failure prediction capabilities of the tuned models were thoroughly analyzed and discussed. The overall mechanical properties and the ductility of the investigated alloys were estimated based on the experimental results and on the information provided by the tuned models. Additionally, a comparison with data collected on the corresponding wrought materials, performing the same experiments, was carried out. The results showed a limited reduction of yield and failure strength and a significant reduction in the ductility of AM materials with respect to their wrought counterparts. Moreover, for the less ductile alloys, a weaker dependence of the strain to fracture from the stress state was observed.