Microstructural Effects on the Fracture Behavior of Binder Jetting 3D Printed Hardmetals

The demand of cemented carbide - usually referred to as hardmetal - tools is increasing and requiring complex geometries to meet extreme specifications. In this regard, conventional manufacturing methods are limited and Additive Manufacturing (AM) emerges as a promising solution. However, changes in processing routes can affect mechanical integrity of AM hardmetals. AM samples typically show characteristics linked to the layer-by-layer process, which can induce variations in mechanical properties depending on layer assemblage orientation. Moreover, microstructural effects on the mechanical behaviour are expected. Within this context, this study evaluates the fracture strength and fracture toughness of three AMed WC-Co grades produced via binder jetting. They were assessed using 3-point bending tests in pristine and micro-notched (via ultrashort pulsed laser ablation) specimens. Weibull parameters and fracture toughness values were determined and compared under various conditions. Mechanical testing data was complemented by fractographic analysis, aiming to identify critical flaws and fracture micromechanisms.