Selective laser melting of typical metallic materials: An effective process prediction model developed by energy absorption and consumption analysis

Abstract

Selective laser melting (SLM) is a laser-based additive manufacturing technique that can fabricate parts with complex geometries and sufficient mechanical properties. However, the optimal SLM process windows of metallic materials are difficult to predict, especially when exploring new metallic materials. In this paper, a universal and simplified model has been proposed to predict the energy density suitable for SLM of a variety of metallic materials including Ti and Ti alloys, Al alloy, Ni-based superalloy and steel, on the basis of the relationship between energy absorption and consumption during SLM. Several important but easily overlooked factors, including the surface structure of metallic powder, porosity of powder bed, vaporization and heat loss, were considered to improve the accuracy of the model. Results show that, to achieve near-full density parts, the energy absorption (Qa) by the local powder bed should be approximately 3–8 times greater than the energy consumption (Qc), and this finding applies to all materials investigated. The value of Qa/Qc highly depends on material properties, particularly laser absorptivity, latent heat of melting and specific heat capacity. Experiments on high-entropy alloy (CrMnFeCoNi) and Hastelloy X alloy, new metallic materials for SLM, have been further conducted to verify the model. Results confirm that the model can predict suitable laser energy densities needed for processing the various metallic materials without tedious trial and error experiments. Indications and uncertainty of the model have also been analyzed.