Metallographic Analysis of the Suitability of a WC-Co Powder Blend for Selective Laser Melting Technology

Abstract

The main objective of this article is to familiarize readers with the first outputs from PhD research by David Bricín, especially with the metallographic analysis, which was carried out on the first series of printed samples. The PhD thesis deals with the processing of powder mixtures based on WC-Co using selective laser melting (SLM) and other technologies. This article specifically deals with the use of SLM for the processing of a WC-Co powder mix. The grains of this powder mixture are not granular, but separate grains of carbides and binders. This powder blend was processed on a 3D SLM printer using various printing parameters. Variable parameters included laser power and scanning speed. Other print parameters were kept constant. The properties of the powder mixture and the printed samples were evaluated by metallographic analysis using light and scanning electron microscopy. These analyses were further supplemented by X-ray diffraction phase analysis, chemical analysis by EDX, and analysis of mechanical properties by compression strength testing. The evaluation of the analyses determined how the printing parameters and the type of powder used affect the development and distribution of the structure in the printed samples and how the mechanical properties of the print are then affected. For example, it has been found that increasing the scanning speed results in a more pronounced mixing between the carbide grains and the binder, which then has a positive influence on the mechanical properties of the print. In addition, the experiments found the energy at which the porosity in the printed samples was significantly reduced, and the direction in which further experiments are to take.