Effects of Co ratio on fatigue life of WC-Co die inserts used in cold forming operations

Abstract

Abstract. Production of fasteners via cold forming requires high forming forces, which induce significant stresses in dies. Therefore, die performance becomes a critical parameter of the fastener production process. Estimation of die life with high accuracy allows to enhance production efficiency and reduce die-related expenditures. Generally, WC-Co hardmetals consisting of 4-30% Co content as a binder are highly preferred in cold forming operations. WC-Co metal-ceramic composite materials offer high wear resistance against frictional forces, high compressive strength, and lower elastic deformation to resist excessive contact pressures, which are primary requirements for cold-forming dies. In this study, experimental investigations were conducted for the determination and comparison of fatigue performance at three different stress amplitudes, utilizing three-point bending fatigue testing with two different grades of WC-Co hardmetals. After the experiments, Goodman-Haigh diagrams were obtained from the experimental results to be utilized in predictive die-life calculations.