Selective laser melting of aluminum die-cast alloy—Correlations between process parameters, solidification conditions, and resulting mechanical properties

Abstract

The additive production technology selective laser melting (SLM) is used for direct fabrication of metal-based functional components. SLM is one of the powder-bed based AM technologies. SLM is well established in serial production for dental restoration as well as for tooling. Main concern for industrial application remains the scope of processible materials and resulting mechanical properties. Toward processing of aluminum alloys commercially available systems exist with comparability in terms of applied process parameters and resulting mechanical properties remaining a challenge. Often no data are available concerning process parameters and mechanical properties. This holds especially for high-power SLM systems with increased build rates as a result of extended laser powers of up to 1 kW. Especially when processing aluminum alloys, the solidification conditions significantly affect the resulting microstructure in terms of size of dendrites and grains. Consequently, the present paper systematically investigates and correlates the process parameters (e.g., laser power, scan speed, layer orientation, preheating, etc.) on the microstructure (electron backscatter diffraction and texture) and resultant mechanical properties (hardness, tensile strength, yield strength, and breaking elongation) for aluminum die-cast alloys. At this, underlying phenomena for typically observed anisotropy of mechanical properties in dependence on layer orientation are further specified.