Flexural strength and finite fatigue life behavior of a fine-grained WC-10Co cemented carbide
WC-Co cemented carbides are composite materials formed by ceramic particles embedded by a metallic binder. As a result of this combination, cemented carbides stand out for its great compromise between mechanical and tribological properties, leading to an increasing application in the industry since...
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| Tipo de documento: | dissertação |
| Data de publicação: | 2023 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositório: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglês |
| OAI Identifier: | oai:upcommons.upc.edu:2117/386693 |
| Acesso em linha: | https://hdl.handle.net/2117/386693 |
| Access Level: | Acesso embargado |
| Palavra-chave: | Carbides cemented carbide fine-grained WC-10Co flexural strength fatigue behavior weibull statistics. Carburs Àrees temàtiques de la UPC::Enginyeria dels materials |
| Resumo: | WC-Co cemented carbides are composite materials formed by ceramic particles embedded by a metallic binder. As a result of this combination, cemented carbides stand out for its great compromise between mechanical and tribological properties, leading to an increasing application in the industry since their introduction. However, cemented carbide components and tools can experience unexpected failure under both monotonic (fracture) and cyclic (fatigue) loading, and this is strongly dependent on the microstructure of the material. An extensive study of the material, including an exhaustive microstructural characterization, flexural testing under four-point bending on both monotonic and cyclic regime (by evaluating the fatigue strength and its reliability in the finite range) and a subsequent fractographic analysis have been performed. Experimental data have been analyzed based on Weibull statistics, regarding both monotonic (flexural strength) and cyclic (fatigue strength). In this work, fine-grained WC-10Co cemented carbide samples were used and reported a variety of results depending on the parameters and sample populations considered. In our test conditions, the reference stress at bending strength was determined as a Weibull parameter to be about 3720 MPa. The associated Weibull parameter accounted for a wide dispersion in the population. SEM observations effectively allowed the identification of critical defects in the microstructure of some samples, leading to two defect-dependent Weibull statistics. Modified staircase methodology was correctly implemented in this work allowed to calculate the finite fatigue strength using a reduced number of samples. Fatigue tests performed (on 3 different stress levels each with 10 samples) confirmed the disparity of the number of cycles to failure among the population. Strength levels close to the found finite fatigue limit survived, in average, more cycles. The analysis realized on only broken specimens presented dispersion among the population which prevented from drawing conclusions. However, evaluation of these tests by Weibull statistical analysis revealed similarities between the flexural strength and the broken fatigue samples, showing a similar trend respect to the distribution of results and established a clustered tendency in the number of cycles to failure around [10,000 - 100,000]. This could allow the possibility in futures works of performing this type of analysis on different hardmetal grades in order to evaluate the influence of the microstructure on the fatigue behavior. |
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