A new industrial process allowing to reach very high cooling rates in the cooling section after soaking of a continuous annealing line for steel sheets is presented. This process constitutes the successful conclusion of a long term research programme, jointly carried out at CRM and Arcelor Cockerill-Sambre for three years, including laboratory experiments, pilot scale trials and several industrial campaigns. It is running on from developments performed in the framework of the HOWAQ (Hot Water Quench) process. The process successively combines a moderate cooling step (600 °C/s for 0.8 mm thick strips), in boiling water, and a faster cooling step (above 700 °C/s), by impinging turbulent cold water in a box. Its main features are simplicity, resulting from advanced developments, soundness, flexibility and cooling homogeneity. As treated steel products are characterized by improved mechanical properties, outstanding surface quality (corrosion resistance) and exceptional flatness. The process is implemented industrially since the beginning of 2002.

In multiphase materials, X-Ray Elasticity Constants (XEC) depend on the nature and volume fraction of each phase constituting the polycrystal. These XEC play a leading role during X-Ray diffraction stress analysis. Self-consistent scale transition models have been developed in order to simulate the XEC characteristics of several two-phase alloys. This work makes possible the quantitative study of the influence of the second phase on the results of X-Ray stress analysis.

From his own experience, the author discusses the need of Metallurgy for theoretical models and their limits. The development of simple but less accurate models has provided a semi-quantitative approach of many complex metallurgical phenomena that has proven useful to orientate research as well as to afford interpretation-based prediction. Such models can be validated within a narrow range only. These approximate models could be substituted for by elaborated and comprehensive calculations that would provide reliable predictions with the help of ever more efficient computers. It remains a difficult task to take satisfactorily into account every internal parameter and boundary condition of a global system. Furthermore, any new observation requests another calculation that gives a clear picture but no comprehensive understanding of the underlying phenomena. Combining experiments, interpretation and prediction modeling along with few dedicated calculations may eventually allow further progress in such a complex domain as Metallurgy.

When producing ultra-thin hot strip, the yield and economy depend on achieving narrow geometrical and material properties fulfilling the increased customers demand. In production, the correct measurement of the strip properties is necessary. This paper gives advanced measuring and control techniques for the parameters concerning thickness profile, flatness profile, coil face profile, temperature profile, surface finish profile of ultra-thin hot rolled strip.

“Consistent BOS Performance” was an ECSC funded project that began with the premise that internal converter shape influences process performance. Plant data were analyzed to quantify the effect of shape on performance and the process of slag splashing was studied in detail, as a means of shape control. It was found that the greatest influence on BOS performance is the availability of bottom agitation and this is affected by slag splashing practices.

Textures and local orientations have been determined in copper alloys after cold rolling and annealing. The measurements show that for a strain below a given threshold a mixed “deformation-recrystallization” texture is obtained after a static primary recrystallization : the {100}<001> cube orientation becomes stronger as annealing procedes, but is not dominating in the final microstructure. Global texture determinations by X-ray diffraction coupled with local orientation measurements by EBSD (Electron Back-Scattered Diffraction) show that in materials cold rolled by 70 and 80%, the orientation changes at the very beginning of the recrystallization process (i.e. at nucleation) are crucial for the formation of the recrystallization texture.

Dans le cadre de l’étude de la fatigue thermique de tuyauteries du parc de centralesnucléaires, des essais de fatigue multiaxiale à grand nombre de cycles sont effectués pourtenter de quantifier l’effet de la multiaxialité et de contrainte moyenne sur la durée devie du matériau et alimenter un modèle d’endommagement à deux échelles. Des outils demesures de champs cinématiques ainsi que d’observations micrographiques sont mis en placeafin de tirer le maximum d’information de chaque essai : comportement cyclique,déformation plastique progressive, scénario d’apparition des fissures. Des résultatsd’essais proportionnels et non-proportionnels sont présentés.

This paper addresses issues of material flows in a selection of modern steel plants,especially the generation of wastes, from a social sciences perspective. I analyse keyfactors structuring waste management decisions through the case of “problem” wastesarising at a steel company’s plants. I discuss how some materials come to be construed asmore problematical than others from a material and technological point of view, but alsoby taking into account organisational and legislative issues, in order to show that theconstruction of the “waste” category needs to be envisioned as resulting from a matrix ofsocio-material causes.

This article synthesizes a number of studies involving both quantitative characterization of precipitate microstructures (size and volume fraction) and modelling of precipitation kinetics. The main experimental methods used are Small Angle X-ray and Neutron Scattering and Transmission Electron Microscopy. The modelling is based on semi-analytical models (coupled differential equations) and on numerical models (based on the discretization of the precipitate size distribution). A variety of systems are studied, both aluminium alloys and steels. After considering isothermal precipitation, the issues of dynamic and non-isothermal precipitation are discussed. Finally, precipitation phenomena occurring during welding are characterized.

Le but de ce travail est une contribution à l’étude de l’efficacité d’utilisation dutraitement de phosphatation au zinc pour la lutte contre la corrosion des armatures dansle béton. Pour réaliser cette conversion chimique superficielle, des échantillons en acierrond à béton ont subi une phosphatation cristalline dans un bain de phosphate de zincmodifié par des ions Ni2+. Par suite, nous avons évalué leur comportement à lacorrosion dans une solution simulée du béton au moyen de différentes techniquesélectrochimiques. Les résultats obtenus montrent que le traitement de phosphatation permetd’améliorer d’une manière significative la résistance à la corrosion de l’acier. En effet,les échantillons phosphatés, par rapport à ceux non phosphatés, présentent des valeurs depotentiel de corrosion et de piqûration plus nobles ainsi que des densités de courant decorrosion plus faibles. Les mesures d’impédances confirment cette tendance, les spectresobtenus montrent une nette augmentation de la résistance de transfert de chargesconjointement à une diminution de la capacité de la double couche électrochimique deséchantillons traités. Cette action protectrice est due au fait que la couche de phosphateobtenue joue le rôle de barrière physique face à la diffusion des ions chlorures d’unepart, sa dissolution en surface dans la solution simulée fortement alcaline libère lesions PO43- rentrant dans la réaction de formation d’un film depassivation jouant le rôle de barrière chimique face à l’amorçage de la corrosion parpiqûres, d’autre part.

Raw materials like metals and minerals contribute by 40% tothe production costs of the industry, whereas the costs forenergy are about 1.6%. Although these figures are for thetotal industrial production, the figures show that it can beexpected that there is a great potential for cost savings in thesteel production, too.

A closed-loop blast furnace automation system was jointly developed by VOEST-ALPINE Industrieanlagenbau (VAI) and VOEST-ALPINE Stahl Linz (VASL). The system, with the tradename VAiron, makes not only the operation of the blast furnace entirely transparent, but stabilizes it also, and permits therefore significant improvements in the regularity of hot metal quality and substantial reductions in production costs. The final goal of the development is the "fully automatic blast furnace" .

Fatigue crack propagation in a welded joint of a cablecar post hasbeen developed, based on parameters measured on real joints. Itmakes it possible to optimise the schedule for inspection of theposts.

Online detection and monitoring of phase transformation using non-destructiveelectromagnetic system in industrial hot strip mill processing of steels are reported. Thesystem renders wide range of possibilities for advanced control and fine tuning of the hotrolling and run-out table cooling parameters. These in turn allow for processmodifications to better control the microstructure of hot rolled bands. In particular,such modifications can attenuate the adverse effects of uncontrollable cooling of hot bandcoils that leads to severely non-homogeneous hot band microstructure. An example ofapplication is given demonstrating how reducing the non-homogeneity of hot bandmicrostructure with the aid of online hot strip mill electromagnetic system can helpeliminating the off-thickness defects in advanced high strength steel full hard stripsthus contributing to lowering the production costs and increasing the yield.

The new casting-rolling plant of Thyssen Krupp Stahl AG is in operation since April 1999. Differences in comparison with other CSP plants are described. The production results at this time are explained together with the range of steel grades and the achieved dimensions. Differences with respect to conventional hot rolled strip are shown in surface quality as well as in mechanical properties and in dimensional tolerances.

The operation of blast furnace No. 2 started in July 1998, raising the CST yearly hot metal production from 3.6 Mt to the present level of 5.0 Mt. In July 2004, after a 6 years long operation, blast furnace No. 2 cumulated a production of 8.16 Mt, moreover ensuring good performance. The paper presents the actions that have been taken to control hearth wear, while sustaining high productivity and low fuel consumption. The results obtained are submitted to a detailed analysis with appropriate reference to the approach that has been followed and the controls that have been implemented.

The coefficient of friction is one of the tribological factors that characterizethe process of multi pass hot rolling. Friction is strongly dependenton inter-pass and in-pass rolling and cooling processingparameters. It can be improved by application of hot lubricationunder specific conditions. This paper builds upon previous studies onthe application of a Coulomb-Norton friction mathematical model, tostudy the influence of hot lubrication for a range of rolling conditions,with a view to define conditions where lubrication is most effective.

This paper describes a model for the simulation of the process of direct reduction of iron ore for steel production. The model is implemented through stand-alone software and the simulation results have been compared with real experimental data. The very good agreement between the actual and simulated data proves that the model, despite its relative simplicity, takes into account all the fundamental phenomena of iron ore reduction.

This paper addresses several experimental techniques, which have been developed and validated with the aim of assessing the mechanical conditions of service-exposed primary plant components, particularly from the point of view of fracture toughness. Such techniques are based on the use of specimens of small or even miniaturized size, as an alternative to the "conventional" methodologies described by commonly used test standards.

Les alliages ferritiques Fe-8 %Al possèdent des propriétés physiques et mécaniques prometteuses pour le développement et la conception de nouveaux types d’aciers allégés. Ces alliages présentent cependant des défauts de surface appelés « roping », apparaissant après l’étape d’emboutissage à froid. La formation de ces défauts est principalement attribuée à la distribution hétérogène des orientations des grains. Dans cette étude, les effets de la quantité de déformation, de la vitesse de déformation et de la température ont été examinés en utilisant la torsion à chaud. Les essais ont été réalisés à des températures comprises entre 900 °C et 1100 °C et des vitesses de déformation comprises entre 0,1 s-1 et 10 s-1. Il a été montré que deux types de recristallisation dynamique pouvaient intervenir durant la déformation à chaud : la recristallisation dynamique continue et la recristallisation dynamique discontinue.