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Jiang, Quanxin (author), Morete Barbosa Bertolo, V. (author), Popovich, V. (author), Sietsma, J. (author), Walters, C.L. (author)Macroscale cleavage fracture toughness of high strength steels is strongly related to the fracture of hard microstructural inclusions. Therefore, an accurate determination of the local stress on these inclusions based on the matrix stress is necessary for the statistical modelling of macroscale cleavage fracture. This paper presents...journal article 2021
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Morete Barbosa Bertolo, V. (author), Jiang, Quanxin (author), Scholl, Sebastian (author), Petrov, R.H. (author), Hangen, Ude (author), Walters, C.L. (author), Sietsma, J. (author), Popovich, V. (author)The through-thickness heterogeneous microstructure of thick-section high strength steels is responsible for the significant scatter of properties along the thickness. In this study, in order to identify the critical microstructural features in the fracture behaviour and allow for design optimisation and prediction of structural failure, the...journal article 2022
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Jiang, Quanxin (author), Morete Barbosa Bertolo, V. (author), Popovich, V. (author), Sietsma, J. (author), Walters, C.L. (author)Thick section S690 QT steel is modelled with a modified multibarrier model that is based on the weakest-link mechanism. Segregation bands are modelled as discrete layers which have different grain size, yield properties, and local fracture parameters from outside of the bands. The results show that embrittlement from segregation bands can...journal article 2022
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Mattos Ferreira, V. (author), Mecozzi, M.G. (author), Petrov, R.H. (author), Sietsma, J. (author)The influence of soaking and cooling rates on the final microstructure of a R260Mn pearlitic railway steel subjected to fast heating is investigated. Fast-heating experiments followed or not by soaking and cooling at different rates were performed using quenching dilatometry on railway steel specimens obtained from the rail head. Additional...journal article 2022
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Morete Barbosa Bertolo, V. (author), Jiang, Quanxin (author), Tiringer, U. (author), Walters, C.L. (author), Sietsma, J. (author), Popovich, V. (author)For structural assessment and optimal design of thick-section high-strength steels in applications under harsh service conditions, it is essential to understand the cleavage fracture micromechanisms. In this study, we assess the effects of through-thickness microstructure of an 80-mm-thick quenched and tempered S690 high-strength steel, notch...journal article 2022
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Morete Barbosa Bertolo, V. (author), Jiang, Q. (author), Terol Sanchez, M. (author), Riemslag, A.C. (author), Walters, C.L. (author), Sietsma, J. (author), Popovich, V. (author)High strength steels are widely used for structural applications, where a combination of excellent strength and ductile-to-brittle transition (DBT) properties are required. However, such a combination of high strength and toughness can be deteriorated in the heat affected zone (HAZ) after welding. This work aims to develop a relationship...journal article 2023
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Abraham Mathews, J. (author), Farahani, H. (author), Sietsma, J. (author), Petrov, R.H. (author), Mecozzi, M.G. (author), Santofimia, Maria Jesus (author)The influence of carbon concentration variations on pearlite formation (20 h at 600 °C) in a case-carburized steel is investigated. The resultant microstructure shows three distinct regions: carburized case, a transition region, and the original core. The microstructural transition from the case to the core regions is observed to be...journal article 2023
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Krugla, M. (author), Offerman, S.E. (author), Sietsma, J. (author), Hanlon, Dave N. (author)The production reality of sheet steels from casting to the end product is such that in the cases of ultra- and advanced high-strength steels, we have to deal with the segregation of elements on macro- and microlevels. Both can have a significant impact on the microstructure formation and resulting properties. There are several production stages...journal article 2024
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Navarro Lopez, A. (author), Hidalgo Garcia, J. (author), Sietsma, J. (author), Santofimia, Maria Jesus (author)The accelerated formation of bainite in presence of martensite is opening a new processing window for the steel industry. However, for a feasible industrial implementation, it is necessary to determine the mechanical behaviour of the steels developed under such conditions. This study focuses on analysing the effects of the formation of...journal article 2018
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Celada-Casero, Carola (author), Sietsma, J. (author), Santofimia, Maria Jesus (author)There is sufficient experimental evidence to propose that the formation kinetics of athermal martensite directly depends on the austenite grain structure from which the martensite forms. Yet, this dependence is frequently ignored. The present study investigates the role of the prior austenite grain size (PAGS) in the martensitic...journal article 2019
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Vittorietti, M. (author), Hidalgo Garcia, J. (author), Galan Lopez, J. (author), Sietsma, J. (author), Jongbloed, G. (author)This study proposes a new approach to determine phenomenological or physical relations between microstructure features and the mechanical behavior of metals bridging advanced statistics and materials science in a study of the effect of hard precipitates on the hardening of metal alloys. Synthetic microstructures were created using multi-level...journal article 2022
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Navarro Lopez, A. (author), Ioannidou, C. (author), van der Wal, E.M. (author), Arechabaleta Guenechea, Z. (author), van den Oever, R. (author), Verleg, M.N. (author), Dalgliesh, R. M. (author), Sykora, J. (author), Akeroyd, F. A. (author), Geerlofs, N. (author), Sietsma, J. (author), Pappas, C. (author), van Well, A.A. (author), Offerman, S.E. (author)Interphase precipitation occurring during solid-state phase transformations in micro-alloyed steels is generally studied through transmission electron microscopy, atom probe tomography, and ex situ measurements of Small-Angle Neutron Scattering (SANS). The advantage of SANS over the other two characterization techniques is that SANS allows...journal article 2020
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Yilmaz, A. (author), Traka, K. (author), Pletincx, S. (author), Hauffman, T. (author), Sietsma, J. (author), Gonzalez Garcia, Y. (author)The role of microstructural defects (dislocation density and grain boundary areas) on the passive film properties formed on cold- and hot-rolled interstitial free (IF) steels is investigated in 0.1 M NaOH solution. Electron backscattered diffraction (EBSD) shows higher microstructural defect density on cold-rolled samples. Potentiodynamic...journal article 2021
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Abraham Mathews, J. (author), Sietsma, J. (author), Petrov, R.H. (author), Santofimia, Maria Jesus (author)In many commercial steel processing routes, steel microstructures are reverted to an austenitic condition prior to the final processing steps. Understanding the microstructure development during austenitization is crucial for improving the performance and reliability of the microstructure that forms from austenite. In this work, austenite...journal article 2023
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Mattos Ferreira, V. (author), Mecozzi, M.G. (author), Petrov, R.H. (author), Sietsma, J. (author)The austenitization of an initial pearlitic microstructure is simulated using the phase field model to achieve insight into White Etching Layer (WEL) formation in pearlitic railway steels. The simulations take into account the resolution of the cementite lamellae within a pearlite colony as well as the presence of pro-eutectoid ferrite. The...journal article 2023
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Arechabaleta Guenechea, Z. (author), van Liempt, P. (author), Sietsma, J. (author)The pre-yield deformation behaviour (i.e., at stresses below the yield stress) of two materials, pure iron and a low-alloy steel, and its anelastic nature are analysed at room temperature, before and after the dislocation structures are varied by plastic deformation. It is shown, based on tensile experiments, that this behaviour can be explained...journal article 2016
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Ou, X. (author), Sietsma, J. (author), Santofimia, Maria Jesus (author)Molecular dynamics simulations have been used to study the effects of different orientation relationships between fcc and bcc phases on the bcc/fcc interfacial propagation in pure iron systems at 300 K. Three semi-coherent bcc/fcc interfaces have been investigated. In all the cases, results show that growth of the bcc phase starts in the areas...journal article 2016
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Abraham Mathews, J. (author), Sietsma, J. (author), Petrov, R.H. (author), Santofimia, Maria Jesus (author)Bainite to austenite reversal is one of the grain refinement techniques employed in carburized steels. However, chemical segregation influences the homogeneity of the bainitic structure, which is seminal to exploit the advantages associated with austenite reversal. It is therefore important to understand the influence of chemical segregation...journal article 2022
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Karewar, Shivraj (author), Hidalgo Garcia, J. (author), Sietsma, J. (author), Santofimia, Maria Jesus (author)The martensitic transformation in pure Fe and its alloys has been studied over many decades. Several theoretical models have been proposed to describe the atomic motion that leads to the fcc-to-bcc martensitic transformation. However, such models do not account for the effect of pre-existing planar defects such as twin boundaries and stacking...journal article 2022
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Sharma, H. (author), Sietsma, J. (author), Offerman, S.E. (author)Polymorphism is the ability of a solid material to exist in more than one phase or crystal structure. Polymorphism may occur in metals, alloys, ceramics, minerals, polymers, and pharmaceutical substances. Unresolved are the conditions for preferential nucleation during polymorphic transformations in which structural relationships or special...journal article 2016