Abstract: Metal additive manufacturing (AM) encompasses the processes used to build objects by combining metallic powder particles on a layer-by-layer basis. In one AM technique, binder jet printing, parts are built by repeatedly distributing thin layers of fine metallic particles in a powder bed and ‘painting’ a planar section of the part using an organic fluid to bind the particles within the specific layer together. The built part is then high temperature sintered to bond contacting particles and create the part shape with the desired physical and mechanical properties. Adjustments in build parameters, powder characteristics, and alloy composition affect both the porosity distribution in the built/sintered part and the ability of the part to densify. To quantify this effect on density, test procedures have been developed to assess the consequences of the manufacturing and feedstock variables on part quality. The metallographic and automated image analysis techniques used to determine pore size and spatial distribution in binder jet printed parts made using 316L stainless steel powders are discussed in this manuscript.
Authors: Thomas F. Murphy and Christopher T. Schade
Keywords: binder jet printing, porosity analysis, automated image analysis