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Babu, A. (author), Ebrahimi, Amin (author), Wu, K. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Additive manufacturing offers a significant potential for producing metallic parts with distinctly localised microstructures and mechanical properties, commonly known as functional grading. While functional grading is generally accomplished through compositional variations or in-situ thermo-mechanical treatments, variation of process...journal article 2023
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Liang, X. (author), Bos, Cornelis (author), Hermans, M.J.M. (author), Richardson, I.M. (author)A cellular automata (CA) model has been developed for solidification simulation considering the kinetic undercooling at the interface. The state-of-the-art model incorporates a decentered growth algorithm to suppress the grid anisotropy and a generalized height function method to calculate the curvature accurately. To develop a CA model which...journal article 2023
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Ebrahimi, Amin (author), Sattari, Mohammad (author), Bremer, Scholte J.L. (author), Luckabauer, Martin (author), Römer, Gert-willem R.B.E. (author), Richardson, I.M. (author), Kleijn, C.R. (author), Hermans, M.J.M. (author)The absorptivity of a material is a major uncertainty in numerical simulations of laser welding and additive manufacturing, and its value is often calibrated through trial-and-error exercises. This adversely affects the capability of numerical simulations when predicting the process behaviour and can eventually hinder the exploitation of fully...journal article 2022
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Ebrahimi, Amin (author), Kleijn, C.R. (author), Hermans, M.J.M. (author), Richardson, I.M. (author)Internal flow behaviour and melt-pool surface oscillations during arc welding are complex and not yet fully understood. In the present work, high-fidelity numerical simulations are employed to describe the effects of welding position, sulphur concentration (60-300 ppm) and travel speed (1.25-5 mms-1) on molten metal flow dynamics in fully...journal article 2021
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Ebrahimi, Amin (author), Babu, A. (author), Kleijn, C.R. (author), Hermans, M.J.M. (author), Richardson, I.M. (author)One of the challenges for development, qualification and optimisation of arc welding processes lies in characterising the complex melt-pool behaviour which exhibits highly non-linear responses to variations of process parameters. The present work presents a computational model to describe the melt-pool behaviour in root-pass gas metal arc...journal article 2021
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Fu, J. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Oxide dispersion-strengthened (ODS) Eurofer steel was laser welded using a short pulse duration and a designed pattern to minimise local heat accumulation. With a laser power of 2500 W and a duration of more than 3 ms, a full penetration can be obtained in a 1 mm thick plate. Material loss was observed in the fusion zone due to metal...journal article 2021
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Fu, J. (author), Davis, T. P. (author), Kumar, A. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Oxide dispersion strengthened (ODS) steels are leading candidates for structural materials in nuclear fission and fusion power plants. Understanding the nature of nano-oxide particles in ODS steels is vital for a better control of the microstructure and mechanical properties to further their applications. In this study, electron microscopy...journal article 2021
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Fu, J. (author), van Slingerland, J. (author), Brouwer, J.C. (author), Bliznuk, Vitaliy (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Pulsed laser beam welding was used successfully to join the oxide dispersion-strengthened (ODS) Eurofer steel. The joining was conducted with a laser power of 2500 W and a pulsed duration of 4 ms. With the filler material being used, a minor material loss and microvoids were observed in the joint. The microstructure of the fusion zone...journal article 2020
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Fu, J. (author), Brouwer, J.C. (author), Hendrikx, R.W.A. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)The present work deals with oxide dispersion strengthened (ODS) Eurofer steel fabricated by powder metallurgy involving mechanical alloying and spark plasma sintering. A heat treatment route including normalising and tempering was applied to the as-produced steel, based on differential scanning calorimetry (DSC) measurement. The...journal article 2020
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Fu, J. (author), Brouwer, J.C. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Oxide dispersion strengthened (ODS) steels are considered to be one of the candidate structural materials for advanced nuclear applications due to their high elevated-temperature strength, corrosion resistance, and radiation tolerance. Joining of ODS steels by traditional fusion joining techniques is not applicable, because the melting...conference paper 2020
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Fu, J. (author), Brouwer, J.C. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Oxide dispersion strengthened (ODS)Eurofer steel was prepared via mechanical alloying (MA)and spark plasma sintering (SPS). Different combinations of MA and SPS parameters were adopted in order to optimise the fabrication process. The experimental results show that the sample milled for 30 h, sintered at 1373 K at a pressure of 60 MPa has...journal article 2019
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Agarwal, G. (author), Kumar, A. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Solidification cracking susceptibility during laser welding was studied experimentally and numerically in advanced high strength steel sheets, namely transformation-induced plasticity (TRIP) and dual phase (DP) steel. Using the same heat input, laser bead-on-plate welding was carried out on single sided clamped specimens at various starting...journal article 2019
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Eftekharimilani, P. (author), Gao, H. (author), Huizenga, R.M. (author), van der Aa, EM (author), Amirthalingam, M. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Advanced high strength steels (AHSS) are increasingly used in automotive industry; thousands of resistance spot welds are applied to car body-in-white. High alloying levels of AHSS result in lower weldability. Residual stresses play an essential role on the formation of defects and the mechanical performance of the weld. An electrical-thermal...conference paper 2018
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Agarwal, G. (author), Gao, H. (author), Amirthalingam, M. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Advanced high-strength steels (AHSS), which are increasingly used in the automotive industry, meet many functional requirements such as high strength and crash resistance. Some of these steels contain high amounts of alloying elements, which are required to achieve the necessary mechanical properties, but render these steels susceptible to weld...conference paper 2018
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Agarwal, G. (author), Amirthalingam, M. (author), Moon, S. C. (author), Dippenaar, R. J. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)Sufficient liquid feeding under constrained solidification conditions like, those experienced in welding and casting, is vital to avoid solidification cracking. We present the results of unique in-situ experimental observations of liquid feeding in a solidifying steel melt pool. Liquid feeding was observed in the inter-cellular regions during...journal article 2018
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Gao, H. (author), Agarwal, G. (author), Amirthalingam, M. (author), Hermans, M.J.M. (author), Richardson, I.M. (author)Hot cracking during laser welding of Transformation Induce Plasticity (TRIP) steel at the edges of steel flanges can be a problem. In this study, modified hot cracking tests were performed by welding on a single-side clamped specimen at various distances from the free edge, while the heat input and external constraints remained constant. In situ...journal article 2018
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Agarwal, G. (author), Kumar, A. (author), Gao, H. (author), Amirthalingam, M. (author), Moon, S. C. (author), Dippenaar, R. J. (author), Richardson, I.M. (author), Hermans, M.J.M. (author)In situ high-temperature laser scanning confocal microscopy is applied to study solidification cracking in a TRIP steel. Solidification cracking was observed in the interdendritic region during the last stage of solidification. Atom probe tomography revealed notable enrichment of phosphorus in the last remaining liquid. Phase field...journal article 2018
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Eftekharimilani, P. (author), van der Aa, E.M. (author), Petrov, R.H. (author), Hermans, M.J.M. (author), Richardson, I.M. (author)The effect of an automotive paint bake (PB) thermal cycle on the microstructural evolution and the mechanical properties of resistance spot welded advanced high strength steel is presented in this work. Mechanical behavior of the heat-treated welds reveals an increase in maximum cross-tension strength, displacement and subsequently energy...journal article 2018
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Pazooki, A.M.A. (author), Hermans, M.J.M. (author), Richardson, I.M. (author)Welding residual stress and distortion are strongly linked together. One of the ways to control or reduce the welding distortions is the manipulation of the generated stresses during welding, and final residual stresses exist in the workpiece (stress engineering). In this paper, the control of gas metal arc butt welding distortion of 500 × 250 ×...journal article 2017
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Eftekharimilani, P. (author), van der Aa, EM (author), Hermans, M.J.M. (author), Richardson, I.M. (author)This paper presents the effects of double pulse resistance spot welding (RSW) on the microstructural evolution, elemental distribution and mechanical properties of a 3rd generation 1 GPa advanced high strength steel (AHSS). In order to investigate the effect of double pulsing, the steel was exposed to single and various double pulse RSW...journal article 2017
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