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Thomas D.J.,University of Swansea | Whittaker M.T.,University of Swansea | Bright G.W.,Corus Research | Gao Y.,University of Warwick
Journal of Materials Processing Technology | Year: 2011

The cut-edge characteristic properties of automotive structures formed during the mechanical blanking and laser-cutting processes significantly influence fatigue life performance. This factor is becoming increasingly important as S355MC and DP600 high strength steels (HSS) grades under investigation exhibit an increased sensitivity to fatigue cracks initiating from cut-edge regions. It was determined that by manipulating the critical cutting process parameters, clearance in terms of mechanical blanking, and by controlling the interrelationship between power and traverse cutting speed during the laser cutting process can result in optimised fatigue lives being achieved. Optimal fatigue lives were attained by minimising the cut-edge surface damage and by controlling the near edge microstructural deformations during each cutting process. It is the critical significance of fatigue which is the limiting factor towards being able to effectively downgauge steel grades used as automotive chassis and suspension components. This research is some of the first that considers the influence of mechanical and laser cut-edge surface quality and internal properties, which has then been partnered to the critical fatigue performance of HSS grades. © 2010 Elsevier B.V. All rights reserved.


Thybaut J.W.,Ghent University | Sun J.,Ghent University | Sun J.,Corus Research | Olivier L.,CNRS Research on Catalysis and Environment in Lyon | And 4 more authors.
Catalysis Today | Year: 2011

An extended microkinetic model for methane oxidative coupling (OCM) including so-called catalyst descriptors has been used for the simulation of experimental data on various catalysts in different setups. The good agreement between experimental data and calculated results over a large range of operating conditions proves the capability of the model being incorporated in a high throughput workflow for OCM catalyst development. The model allows the selection of the optimal operating conditions for catalyst evaluation. The effects of operating conditions and catalyst texture properties such as feed flow rate, temperature, pressure and porosity, BET-surface area, and tortuosity, have been investigated using the model. By varying the value of catalyst descriptors, C2 product yields have been calculated to show the effects of these descriptors on the catalytic chemistry. With this microkinetic model the yield of methane oxidative coupling products was optimized using a genetic algorithm followed by the Rosenbrock and the Levenberg-Marquardt method. The optimized parameters include catalyst descriptors, operating conditions and catalyst texture properties. Results show that even with optimal surface chemistry and operating conditions, limits exist on the attainable yield. Nevertheless, these limits were found to be beyond the yields obtained with state of the art OCM catalysts, which opens up perspectives for further catalyst improvement. © 2010 Elsevier B.V.


Rana R.,Indian Institute of Technology Kharagpur | Rana R.,RWTH Aachen | Rana R.,Corus Research | Singh S.B.,Indian Institute of Technology Kharagpur | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2010

Biaxial stretching behavior of a promising high-strength copper-alloyed interstitial-free (IF) steel has been investigated under various processing conditions using bulge tests. Hill theory and von Mises yield criterion have been used to analyze the results. It is revealed that copper-alloyed IF steel in continuous-annealed (CA) condition exhibits the highest equivalent strain at fracture and largest limiting dome height (LDH) among all the processing conditions. However, these values are lower in copper-alloyed interstitial steel than in traditional interstitial-free-high-strength (IF-HS) steels due to the presence of solute copper and copper precipitates in the former. © 2010 The Minerals, Metals & Materials Society and ASM International.


Wen S.W.,Corus Research | Colegrove P.A.,Cranfield University | Williams S.W.,Cranfield University | Morgan S.A.,BAE Systems | And 2 more authors.
Science and Technology of Welding and Joining | Year: 2010

Considerable residual stress and distortion can be produced by friction stir welding, impeding industrial implementation. Finite element analysis has been used to develop three innovative rolling methods that reduce residual stress and distortion in friction stir welds. Of the three methods, post-weld direct rolling where a single roller is applied to roll the top surface of the weld after the weld metal has cooled to room temperature proved the most effective. The residual stress predictions from the model compared favourably with residual stress measurements reported in an accompanying paper. Finally, the effectiveness of using post-weld direct rolling is illustrated with an industrial example of a large integrally stiffened panel, where the distortion was virtually eliminated. © 2010 Maney Publishing.


Hili J.,Imperial College London | Olver A.V.,Imperial College London | Edwards S.,Corus Research | Jacobs L.,Corus Research
Tribology Transactions | Year: 2010

At very high speeds, elastohydrodynamic (EHD) films may be considerably thinner than is predicted by classical isothermal regression equations such as that due to Dowson and Hamrock. This may arise because of viscous dissipation, shear thinning, frictional heating or starvation. In this article, the contact between a steel ball and a glass disc over an entrainment speed ranging from 0.05 m s-1 to 20 m s-1 was studied. Two sets of tests were performed. In the preliminary testing, the disc was driven at speeds of up to 20 m s-1 and the ball was driven by tractive rolling against the disc, its speed being determined using a magnetic method. After all possible explanations for the reduction in film thickness at high speeds were considered, it was shown that the results, which fall well below classical predictions, are consistent with inlet shear heating at the observed sliding speeds. Another set of tests was then performed, with both disc and ball driven separately, so that the accuracy of the shear heating theory for different types of oils and at different sliding conditions could be assessed. It was found that the thermal correction factor predicts the trend of film thickness behavior well for the oils tested and is particularly accurate at certain slide-roll ratios (depending on the type of oil). Experimental data were also used to obtain improved coefficients for the correction factor for different types of oil to achieve better prediction of film thickness at high speed throughout the whole range of slide-roll ratios. © Society of Tribologists and Lubrication Engineers.


Boom R.,Corus Research | Riaz S.,Corus Research | Mills K.C.,Imperial College London
Ironmaking and Steelmaking | Year: 2010

Starting in 1997 with the 5th International Conference on Slags and Fluxes a survey on research on slags has been done preceding the next conference on slags and fl uxes. Trends from 1980, the year of the fi rst conference in Halifax, Canada, have been traced and discussed. © 2010 Maney Publishing.


Adema A.T.,Technical University of Delft | Yang Y.,Technical University of Delft | Boom R.,Technical University of Delft | Boom R.,Corus Research
ISIJ International | Year: 2010

The cohesive zone, where the ore fed into the blast furnace softens and melts, is critical to the blast furnace performance and stability due to its influence on the gas and solid flow. Here we describe a project for the development of a process model to predict the cohesive zone properties and results of an important part of the work; the solid and gas flow models. The process model will be developed to describe a realistic solid burden flow and the formation of the cohesive zone, its shape, location, structure and permeability. This will be achieved using various simulation and computing tools: a combination of the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD), the coupled DEM-CFD approach, together with models for the thermodynamics and reaction kinetics. The key benefits of the coupled approach lie in the coupling of the continuous phase and the discrete particles, and the possibility of introducing thermodynamics and reaction kinetics into the system in a more realistic manner. DEM and coupled DEM-CFD simulations in several geometries are presented for reduced scale blast furnace investigation on the influence of non-spherical particles and gas flow on the solid flow. A large influence of the geometry shape and boundary conditions on the solid flow was also found. © 2010 ISIJ.


De Vooys A.,Corus Research | Van Der Weijde H.,Corus Research
Progress in Organic Coatings | Year: 2011

The corrosion of coated steel with microcracks in the coating was monitored as time progressed using EIS and SVET simultaneously, i.e. to the same sample during the same measurement. The microcracks were created by environmental stress cracking after a controlled deformation. Both methods revealed an initial stage with an exponentially increasing corrosion current, and a second stage where the corrosion current increases linearly. SVET measurements showed that only a few of the cracks present participate in the corrosion process and that the corrosion positions are constant. EIS measurements showed that the cracks are partially crazes, and that the corrosion mechanism changes from the first to the second stage. The mechanistic information could be combined to show the transition from uniform corrosion through pores to a local cell type mechanism, even though the cracking process is stochastic and the electrochemical data shows a large variation between samples. © 2011 Elsevier B.V.


Horn A.J.,Corus Research
COST ACTION C26: Urban Habitat Constructions under Catastrophic Events - Proceedings of the Final Conference | Year: 2010

When designing structures to resist extreme or unplanned events such as explosions, impacts or earthquakes, it is necessary to define both the 'demands' placed on the materials of construction and the 'resistance' available. Integrity is ensured when resistance exceeds the demand with a suitable margin of safety. This paper characterises the fracture resistance of a grade S355J0 steel section subject to a combination of high loading rates and high temperatures. Conventional J-Resistance (J-R) curve tests are used to characterize quasi-static fracture resistance over a wide range of temperatures and instrumented, pre-cracked Charpy tests are used to characterise fracture resistance at impact loading rates over the same temperature range (ambient to +550°C). The results show that tearing resistance increases with increasing loading rate at all temperatures studied. Tearing resistance generally decreases with increasing temperature, but this relationship is also dependent on loading rate. © 2010 Taylor & Francis Group, London.


Mulder J.,Corus Research | Vegter H.,Corus Research
International Journal of Material Forming | Year: 2010

The widely accepted concept of isotropic hardening implies that the ratio between a stress for any straight strain path and the reference flow stress remains constant. Measured hardening curves of for instance bake hardening and dual phase steels show however that these ratio are not always constant. To capture this phenomenon in finite element simulations the concept of an evolving yield locus is proposed. A finite difference model for the simulation of axisymmetric sheet forming processes is used to implement this model. Simulation results show that there is a major impact of the yield locus evolution. The reliability of simulation results with isotropic hardening can be significantly improved if the shape of the yield locus is fitted to an average taking all measured data of the hardening curves into account. © 2010 Springer-Verlag France.

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