Browsing by Author "Martinez, Roberto Fernandez"
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Item Material Fracture Life Prediction Under High Temperature Creep Conditions Using Support Vector Machines And Artificial Neural Networks Techniques(Institute of Electrical and Electronics Engineers Inc., 2021) Martinez, Roberto Fernandez; Jimbert, Pello; Callejo, Lorena M.; Barbero, Jose Ignacio; CIRMETAL; Tecnalia Research & Innovation; PROMETALOne of the most applied materials to manufacture critical components in power plants are martensitic steels due to their high creep and oxidation resistance. In this work, the fracture life of martensitic steels that are designed based on the P92 standard is modeled in order to better understand the relation between its service life and its composition and its thermal treatment. This feature is usually studied by performing creep tests, although carrying out tests of this type are really cost and time consuming. To solve this problem, a multivariate analysis and a training-testing model methodology were performed using a dataset formed by 344 creep tests with the final goal of obtaining a model to predict the fracture life of the material based on several nonlinear techniques like support vector machines and artificial neural networks. Once the models were defined based on predicting with the better generalization capability to cover the whole scenario of the problem, those were compared to determine which one was the most accurate among them. Finally, it was concluded that the model's performance using the proposed methodology based on artificial neural networks got the most accurate results, achieving low errors of approximately 6.14% when predicting creep behavior under long service times.Item New chromium steel grade for creep applications(2022-10-11) Callejo, Lorena M; Barbero, José Ignacio; Serna-Ruiz, Mónica; Eguizabal, David; Martinez, Roberto Fernandez; Jimbert, Pello; Calleja-Saenz, Beatriz; López, Alejandra; Tecnalia Research & Innovation; CIRMETAL; PROMETAL; SGIn this study, a novel Chromium steel grade (COIN2) is produced as a result of a new steel composition and an innovative heat treatment. This new steel grade COIN2 evolves from the P92 steel grade and other novel steel grade recently created by the authors (COIN), and represents an enhancement of hardness, tensile properties, and creep behaviour with respect to them, which validates the metallurgical strategy used for further research in order to increase the efficiency of power plants and thus reduce the CO2 emissions. The characterization reveals a significant property improvement with the innovative thermal treatment, contributing to the production of a novel and more competitive steel grade for creep applications.