Modelling of the damage initiation at WC/WC and WC/Co boundaries in WC-Co tool material at the microstructure scale: Application to the tool/chip contact

• Published in: International journal of refractory metals & hard materials Vol. 119; p. 106508
• Main Authors: Agode, K.E., Wolff, C., Guven, M., Nouari, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2024
• Subjects: Cohesive interfaces; Damage; Finite element analysis; Microstructure model; Temperature dependent behaviour; Traction-separation cohesive law; WC-co; WC-co; Cohesive interfaces; Microstructure model; Traction-separation cohesive law; Temperature dependent behaviour; Finite element analysis; Damage
• ISSN: 0263-4368; 2213-3917
• DOI: 10.1016/j.ijrmhm.2023.106508

In machining process, the wear of tungsten‑cobalt carbide cutting tools (WC-Co) is the result of different wear mechanisms such as abrasion, adhesion and diffusion. At the microstructure scale, the presence of microcracks in the carbide grain boundaries can be observed of the tool and in the WC/Co interfaces on the cutting surface. These microcracks are the cause of the WC-Co pull-out clusters from the cutting tool face. In this work, simulations were set up to evaluate the number of WC/WC and WC/Co interfaces that are likely to be damaged first. The behaviour of each phase was modelled by thermo-elasto-plastic behaviour and cohesive interfaces of zero thickness were used to simulate the behaviour of WC/WC and WC/Co interfaces. Different quasi-realistic microstructures were generated by an algorithm to evaluate the dispersion of the results. These microstructures are surrounded on three sides by an assumed homogeneous WC-Co embedding. The microstructure and the embedding form a part of the cutting tool with one side rubbing against a rigid chip to locally reproduce the chip/tool contact. The results of this study show the influence of the cobalt content, temperature, friction coefficient and orientation of the interfaces on the number of interfaces likely to be damaged first. •Development of finite element simulations to study the initiation of WC/WC and WC/Co boundary damage in quasi-realistically constructed WC-Co hard metal microstructures subjected to typical machining mechanical loads.•Modelling of the WC/WC and WC/Co boundaries using cohesive interfaces whose behaviour is described by a stress-separation law where the required parameters are stiffnesses, maximum stresses and maximum displacements.•Identification of the maximum stresses for the WC/WC and WC/Co boundaries by simulating experimental microbeam tests from the literature. The maximum stresses were considered identical for both types of boundaries.•In order to locally simulate the contact between the chip and the tool, the square microstructures were surrounded on three sides by a WC-Co embedding assumed to be homogeneous, the whole of which represents a part of a cutting tool rubbing against a rigid chip.•The results of these simulations show that by increasing the cobalt content, temperature and friction coefficient, the number of interfaces that are likely to be damaged first increases. In addition, the damage initiation criterion is also influenced by the orientation of the interfaces. These orientations change depending on the sliding direction of the chip.