Utku Ahmet Özden, Keng Jiang, Alexander Bezold, Christoph Broeckmann, Jose María Tarragó, Alvaro Mestra, Luis Llanes

Numerical simulation of fatigue crack propagation in WC-Co hardmetal

Introduction

Numerical simulation of fatigue crack propagation in wc-co hardmetal. Study mesoscale fatigue crack propagation in WC-Co hardmetals via numerical simulation using a continuum damage mechanics model in Abaqus. Validated with experiments.

Abstract

WC-Co cemented carbides (hardmetals) are a group of composite materials exhibiting outstandingcombinations of hardness and toughness. As a consequence, they are extensively used for highlydemanding applications, such as cutting and drilling tools, where cyclic loading is one of the mostcritical service conditions.A numerical study of the mesoscale fatigue crack growth in WC-Co is here conducted. Within thiscontext, a model based on a continuum damage mechanics approach was implemented incommercial solver Abaqus/Explicit for simulating the crack propagation in the material. Separatedamage laws, based on brittle failure and fatigue, were used for describing the mechanicalresponse of WC and Co phases, respectively. Material parameters for the carbide phase weretaken from literature, whereas those for the metallic phase were experimentally determined in amodel binder-like Co-base alloy, i.e. one with a composition representative of the binder phasewithin a commercial hardmetal grade.In order to validate the approach used, a numerical model based on a real damaged microstructurewas generated. It is found that proposed model is capable of capturing damage evolution withcyclic loading in WC-Co, as numerical results reflect satisfactory agreement with real crack patternresulting from experiments.

Review

This paper addresses the critical issue of fatigue crack propagation in WC-Co cemented carbides, a material class renowned for its exceptional hardness and toughness, making it indispensable in highly demanding applications like cutting and drilling tools. Given that these applications frequently involve cyclic loading, understanding and predicting fatigue failure is paramount for enhancing material design and service life. The authors present a numerical study focused on simulating mesoscale fatigue crack growth, offering a multi-phase damage mechanics approach to tackle this complex phenomenon within these composite materials. The methodological core of this work lies in the implementation of a continuum damage mechanics (CDM) approach within the commercial solver Abaqus/Explicit. A key innovation is the differentiation of damage laws for the constituent phases: brittle failure for the hard WC phase and a fatigue-based damage law for the more ductile Co binder phase. This specific treatment of damage for each phase, utilizing literature-derived parameters for WC and experimentally determined parameters from a representative Co-base alloy for the binder, demonstrates a thoughtful attempt to capture the distinct mechanical responses at the mesoscale. Such an approach is crucial for accurately modeling the synergistic behavior of these composite materials under cyclic stress. A significant strength of this study is the validation strategy employed, where a numerical model generated from a real damaged microstructure was utilized to assess the predictive capabilities of the proposed CDM framework. The reported satisfactory agreement between numerical results and experimental crack patterns provides compelling evidence that the model is indeed capable of accurately capturing damage evolution under cyclic loading in WC-Co. This successful validation underscores the potential of this mesoscale numerical simulation to offer valuable insights into the complex mechanisms governing fatigue crack propagation in hardmetals, paving the way for more robust material design and performance prediction in demanding industrial applications.

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