Dorronsoro-Larbide, A. (Aritz)

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    Digital image correlation after focused ion beam micro-slit drilling: A new technique for measuring residual stresses in hardmetal components at local scale
    (Elsevier, 2023) Alkorta-Barragán, J. (Jon); Sánchez-Moreno, J.M. (José Manuel); Pan-Cabo, A. (Aldara); Castaño-Carmona, E. (Enrique); Navarrete-Cuadrado, J. (Jazmina); Dorronsoro-Larbide, A. (Aritz)
    A new method has been developed for measuring residual stresses at the surface of hardmetal components with higher spatial resolution than standard X-ray diffraction methods. It is based on measuring the surface displacements produced when stresses are partially released by machining a thin slit perpendicularly to the tested surface. Slit machining is carried out by focused ion beam (FIB). Measurement of the displacement fields around the FIB slit are performed by applying an advanced digital image correlation algorithm based on Fourier analysis with sub-pixel resolution. This method compares SEM images of the same area of the hardmetal surface before and after slitting. The method has been successfully applied to as-ground and femto-laser textured surfaces showing good correlation with the standard sin2 ψ XRD technique. It is concluded that texturing induced by laser pulses in the femtoseconds regime is not perfectly adiabatic, since residual stresses are reduced by 15%
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    A microstructure-based constitutive model for eutectoid steels
    (2024) Gil-Sevillano, J. (Javier); Alkorta-Barragán, J. (Jon); Martínez-Esnaola, J.M. (José Manuel); Rodríguez-Páez, J. (Jorge); Dorronsoro-Larbide, A. (Aritz)
    This work presents a constitutive model for eutectoid steels based on their two-phase lamellar microstructure. The model accounts for the individual behaviour of both ferrite and cementite, with perfect interphase adhesion assumed. It considers anisotropic hardening mechanisms in ferrite derived from the lamellar structure of pearlite while ignoring the crystal structure of either phase. The model also accounts for the evolution of orientation and spacing of lamellae under directional deformation, along with the evolution of internal stress distribution in both phases. Due to its simplicity, the model has very few calibration parameters but is still able to reproduce complex strain paths and loading conditions with excellent accuracy. The model was compared with tensile, compression and torsion tests from a 13-pass wire drawing series (up to drawing strains of 2.7) and reproduced accurately the mechanical response under any loading condition. The robustness of the model lies in the fact that it is able to recreate the evolution of internal stresses built in cementite and ferrite. Such internal stress evolution was confirmed to reproduce accurately the stress partitioning observed in neutron and X-ray diffraction tests reported in literature. Moreover, the model contributes to the understanding of the rapid broadening of cementite diffraction peaks observed during in-situ tensile tests of patented wires.
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    Surface texturing, residual stresses and edge treatment of hardmetal tools by means of femtosecond pulsed laser
    (Elsevier, 2024) Soria-Biurrun, T. (Tomás); Dorronsoro-Larbide, A. (Aritz); Navarrete-Cuadrado, J. (Jazmina); Lozada-Cabezas, L. (Lorena); Pan-Cabo, A. (Aldara); Castaño-Carmona, E. (Enrique); Alkorta-Barragán, J. (Jon); Sánchez-Moreno, J.M. (José Manuel)
    Laser induced periodic surface structures (LIPSS) have been produced at the surface of a WC-Co turning insert by femtosecond pulsed laser ablation. Wavelengths of approx. 500 nm have been obtained with a 1030 nm incident radiation and with a spot size of 30 μm. No thermal damage is induced by following this procedure, although a slight surface stress relaxation is detected as fluence increases. The higher material removal needed for cham fering operations requires accumulated fluences over 1 kJ/cm2 . At lower energy densities, material removal is not completed. If fluence is increased by reducing the laser spot size, material removal is also inefficient since signicant amount of debris is accumulated on the irradiated areas. Best chamfering strategy involves the com bination of relatively large spot sizes and fluences. Form factors (Κappa) of the chamfered cutting edges range from 4 to 10 although the laser is oriented at 45◦ of the rake face. Lower Κ values can be obtained by adjusting the laser focus along the machining process.