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Fatigue performance improvement of electrical discharge machined hardmetals by means of combined thermal annealing and surface modification routes Llanes Pitarch, Luis Miguel Casas Aguirregomezcorta, Begoña Salán Ballesteros, Maria Núria Mestra Rodríguez, Álvaro Miguel Torres Hernández, Yadir Universitat Politècnica de Catalunya. Departament de Ciència dels Materials i Enginyeria Metal·lúrgica Universitat Politècnica de Catalunya. CIEFMA - Centre d'Integritat Estructural, Fiabilitat i Micromecànica dels Materials Universitat Politècnica de Catalunya. GIOPACT - Grup de Recerca d'Igualtat d'Oportunitats per a l'Arquitectura, la Ciència i la Tecnologia Àrees temàtiques de la UPC::Enginyeria dels materials::Assaig de materials::Assaig de fractura Àrees temàtiques de la UPC::Enginyeria mecànica Fracture mechanics Materials Fatigue Cemented carbides WC-Co Electrical discharge machining Fatigue strength Residual stresses Surface modification Assaigs de materials -- Propietats mecàniques Electrical discharge machining (EDM) provides an effective means of shaping hardmetals. However, it is also known that surface integrity of these materials may be affected by EDM, degrading their tribomechanical characteristics. This work focuses on assessing the use of two different surface modification routes: thermomechanical treatments (shot blasting, polishing and final high temperature annealing) and/or physical vapor deposition of hard coatings, for improving the fracture and fatigue strength of an EDM-shaped fine-grained hardmetal grade. In doing so, an optimal EDM's surface finish variant and a diamond ground and polished one are used. Mechanical behavior is evaluated under four-point bending and fatigue characterization is given in terms of fatigue limit following the staircase method. Experimental results indicate that both approaches markedly decrease the lessening effect of EDM on the mechanical strength of hardmetals, although a complete fracture and fatigue strength retention is only achieved by combining both of them. The improved mechanical behavior is rationalized on the basis of the beneficial changes induced by surface modification on the effective residual stress field at the surface of EDM-shaped hardmetals, as assessed by a linear elastic fracture mechanics analysis combined with fractographic examination. Postprint (published version) 2013-01 Article Llanes, L. [et al.]. Fatigue performance improvement of electrical discharge machined hardmetals by means of combined thermal annealing and surface modification routes. "International journal of refractory metals and hard materials", Gener 2013, vol. 36, p. 60-65. 0263-4368 https://hdl.handle.net/2117/19759 10.1016/j.ijrmhm.2011.12.008 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ Restricted access - publisher's policy Attribution-NonCommercial-NoDerivs 3.0 Spain 6 p. application/pdf