Gonzalez-Ojeda, Roberto

Main Affiliation

Facultad de Ingeniería - CampCM

Preferred name

Official Name

Gonzalez Ojeda, Roberto

ORCID

0000-0003-2319-1631

Researcher ID

DTL-2716-2022

Scopus Author ID

56314856300

Now showing 1 - 10 of 35

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La temperatura de la intercara arrabio/refractario como variable determinante de los mecanismos de corrosión del crisol del horno alto
(1998)
Verdeja González, Luis Felipe
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Pusek, P., Alfonso
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Fernández, Ángel Alejandro
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Gonzalez-Ojeda, Roberto
El desgaste de materiales en el horno alto puede realizarse bajo la consideración de mecanismos estrictamente abrasivos o con el predominio de las componentes químicas y erosivas resultantes de la circulación de fluidos sobre el refractario. No obstante, aunque en determinadas situaciones, la abrasión o las componentes químicas pueden resultar los mecanismos controlantes, es necesario considerar que todos ellos (abrasión, erosión, desgaste químico, adhesión y desgaste térmico-choque térmico) "cooperan" en la degradación del refractario del horno, Para cualquiera de los mecanismos que intervenga en el desgaste de los materiales, resulta conveniente conocer el valor de la temperatura a lo largo de las intercaras del refractario con los sólidos, líquidos o gases presentes en el horno. En la ponencia será desarrollada de forma específica, la importancia que tiene la temperatura en la intercara refractario-arrabio sobre el desgaste de los materiales del crisol. Se discutirán las diferentes hipótesis de transporte (energía, cantidad de movimiento y materia) más adecuadas para la obtención de la temperatura de intercara.
2 13Scopus© Citations 4
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Wear in ultrafine hardmetal mills manufactured by sinter + HIP
(Metal Powder Industries Federation (MPIF), 2006-12-01)
Sánchez-Moreno, José Manuel
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Ordóñez, Alejandro
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Gonzalez-Ojeda, Roberto
Ultrafine WC-Co milling tools were wear-tested in finishing machining conditions. Mills manufactured in the laboratory followed the powder metallurgy route for ultrafine grades. Total density in hardmetal grades of 0.2 and 0.4 μm was achieved through the Sinter + HIP technique. Wear in laboratory mills was compared with wear in coarse and ultrafine grade commercial mills. All mills cutting edges suffered wear mainly in the abrasive and chipping form. Chipping was excessive and peculiar in form in the laboratory mills; a slight presence of the fragile η phase was discovered. Laboratory mills showed similar wear to the commercial coarse grades, and much more than that of commercial ultrafine grades. A lack of toughness is suggested due to a small difference in the WC mean grain size, in the Co mean free path (λ) and in its distribution: homogeneous in laboratory mills and heterogeneous in the commercial ones. ©Metal Powder Industries Federation (MPIF)
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Superplasticity of ultrafine grained low-carbon HSLA steels
(2012)
Verdeja González, José Ignacio
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Quintana, María José
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García García, José Ovidio
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Verdeja González, Luis Felipe
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Gonzalez-Ojeda, Roberto
Steels with ultrafine grained structure may present superplastic behavior at specific temperatures and strain rates that allow the grain boundary sliding mechanisms to be activated. The work presents high temperature tension tests in a low carbon, low alloy steel obtained by advanced thermomechanical controlled rolling processes, showing at 800°C elongations as high as 200%. The microstructure of the steel was analyzed in order to identify ferrite and pearlite grain boundaries, and their interaction after the specimens were deformed, showing intergranular decohesions, restored ferrite grains and elimination of banded structure, which are evidence of superplastic mechanisms in this material which is, in fact, ultrafine grained as demonstrated by quantitative metallographic techniques and grain size distribution analysis.
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Using FEM to determine temperature distribution in a blast furnace crucible
(2000)
Verdeja, Luis Felipe
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Gonzalez-Ojeda, Roberto
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Ordóñez, Alejandro
Temperature distribution in the crucible of a blast furnace is an important operation variable that is a function of the materials used in its construction, temperatures reached in the pig iron-refractory interface, and cooling-system performance. Defining the crucible zones where high shear and tensile stresses are reached is an important step in developing a tribological model to understand and predict high wear zones and crucible life. In this work, temperature distribution was simulated using the finite-element method for a blast furnace built following the ceramic solution (oxide and nitride ceramics in contact with the pig iron and carbon and microporous graphite blocks in contact with the refrigeration system).
Scopus© Citations 8 1 1
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Effect of Mo on high entropy Ti-Nb-Zr-Ta alloy: Phase equilibria, microstructure and mechanical properties
(2023)
Aranda, Víctor A.
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Figueroa, I. A.
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Amigó-Borrás, V.
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Gonzalez-Ojeda, Roberto
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Lozada Flores, Octavio
Thermal and mechanical properties of Ti-Nb-Ta-Zr high entropy alloys are often influenced by element content and manufacturing routes, producing significant differences between mechanical properties and microstructure. This work presents a Ti-Nb-Ta-Zr alloy in which Mo is added by adjusting the composition with phase equilibria simulation, improving the mechanical properties based on a mixture of two chemically different solid solutions (BCC1 and BCC2). The materials were produced by arc-melting suction casting. Characterization of the dendritic and interdendritic zones was carried out by means of X-ray spectroscopy, indicating the segregation of Ta and Nb in BCC1 and Zr and Ti in BCC2 phases. The dislocation density increased preferentially in the interdendritic Zr-Ti rich zones. The mechanical properties results were related to the chemical differences between the BCC1 and BCC2 lattice parameters induced by the Mo addition. With Mo segregating between both BCC cells, the resulting microstructure increased the yield strength, being confirmed with the kernel average maps, which showed that, after compression tests, the interdendritic zone accumulated a high density of dislocations, resulting in the segregation of Ti and Zr, affecting the mechanical response of Mo containing alloy. © 2023 Elsevier B.V.
2 14Scopus© Citations 21
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Warm-stamping mechanical behavior and microstructural characterization of Al-Si metal sheets using water refrigerated tooling
(IEEE, 2026)
Estrada-Warn, Paola
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Garcia-Santibañez, G. J.
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Jauregui-Pablos, M.
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Vazquez-Gomez-Orduña, Sebastián
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Gonzalez-Ojeda, Roberto
The use of water refrigerated tooling in a laboratory scale was used to simulate conditions of warm (500°C) stamping of aluminum plates with 0.8 mm in thickness. The work presents load-displacement curves of room temperature and heat treated samples during stamping at 120 and 240 mm/min, effect of the treatment in the anisotropic characteristics of the rolled sheet plate and electron microscopy analysis along with element detection, as this alloy contains small amounts of silicon. The processes resembles a solution treatment and, thus, also an aging treatment at 120°C for 12 h was carried out in order to understand the application possibilities of the manufacturing process in the automotive or aero-space industry. © The authors © IEEE.
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Microstructures of a pressure die cast Al-8.5%Si-3.5%Cu alloy
(2017)
Barbés Fernández, Miguel Ángel
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Quintana, María José
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Verdeja González, José Ignacio
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Gonzalez-Ojeda, Roberto
Quantitative microstructural measurements of constituents of an Al-Si-Cu alloy, used to manufacture a part with thin sections by Pressure Die Casting (PDC), do not correspond to phase diagram calculations. A simulation of the liquid velocity when filling the mold was made in order to understand the relation between this parameter and pressure, cooling rate and the eutectic amount and morphology. Also, the microstructures of the same alloy solidified in a ceramic crucible (low cooling rate) and in a metal flask (high cooling rate) were compared to those obtained by PDC to analyze the role of pressure on the displacement of eutectic composition and formation of different eutectic morphologies. The amount of constituents varies with distance from the mold walls, producing higher or lower pressure zones, which may be estimated from the Al-Si phase diagram simulation at different pressures. As these pressures must be very high (∼ 2 GPa), a possible explanation for the displacement of the eutectic point is the combination of high cooling rate of the manufacturing process, entrapment of gases during solidification and influence of the alloying elements.
1 8
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A Parametric Study of Laser-Directed Energy Deposited DSS 2205: Microstructure and Mechanical Properties Perspectives
(Springer Science and Business Media LLC, 2025)
Mahey, Vishal
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Johnson, Grant A.
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Burad, Prayag
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Gonzalez-Ojeda, Roberto
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Quintana, Maria J.
Duplex stainless steels (DSS) are corrosion-resistant materials with excellent mechanical properties. This family of steels is only a recent addition to the additive manufacturing (AM) realm due to the limited availability of DSS powder in the past. This study has investigated the effect of varying energy flux (laser power and scanning speed) in a laser-based directed energy deposition AM process on the as-deposited materials state of DSS 2205, a material widely used in marine applications. The primary focus was to understand how changes in laser power (200 W and 300 W) and scanning speed (10 mm/s and 15 mm/s) influence key microstructural features such as phase distribution (δ-ferrite and γ-austenite), grain size, morphology, defects, and microhardness of the as-deposited material. Microstructural analysis revealed a significant correlation between the processing parameters and the resulting microstructure. Increasing the scanning speed reduces the defect content in the samples, while increasing laser power results in larger δ-ferrite grains. The hardness was influenced by both the γ-austenite content and the δ-ferrite grain size. This study provides a pathway for tailoring directed energy deposition (DED) conditions to achieve high-quality and dimensionally accurate components, particularly suited for demanding marine applications. ©The authors ©Springer ©JOM.
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Ultrafine-grain Steels: Mechanical Behavior
(2016)
Quintana Hernández, María José
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Gonzalez-Ojeda, Roberto
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MARÍA JOSÉ QUINTANA HERNÁNDEZ;576914
In recent years, both the steelmaking industry and laboratories in different parts of the world, have shown an increasing interest in reaching an industrial-level production of ultrafine grained steels (also known as ultrafine ferrite), which have a grain size d lower than 5 μm, and enhanced mechanical resistance and fracture toughness. At room temperature, the capacity of the material to be deformed during bending or drawing operations (typical of requirements for automotive parts applications) depends on the interaction of a hard and a soft phase in the microstructure. On the other hand, at high temperatures, these steels may show superplastic behavior if deformed at a precise combination of temperature and strain rate.
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Nodal wear model: corrosion in carbon blast furnace hearths
(2003)
Verdeja González, Luis Felipe
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Gonzalez-Ojeda, Roberto
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Alfonso, A.
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Barbés Fernández, Miguel Ángel
Criterions developed for the Nodal Wear Model (NWM) were applied to estimate the shape of the corrosion profiles that a blast furnace hearth may acquire during its campaign. Taking into account design of the hearth, the boundary conditions, the characteristics of the refractory materials used and the operation conditions of the blast furnace, simulation of wear profiles with central well, mushroom and elephant foot shape were accomplished. The foundations of the NWM are constructed considering that the corrosion of the refractory is a function of the temperature present at each point (node) of the liquid metal-refractory interface and the corresponding physical and chemical characteristics of the corrosive fluid.
2Scopus© Citations 10 3

Gonzalez-Ojeda, Roberto

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