The blow-in of CSN blast furnace n°3 in 2006 is reported with a focuson a large solidified salamander that had to be tapped. Analyticaland finite element models have been created to predict the expansionphenomena. The predicted values are compared with the hearth shellstress and strain measurements executed during the blow-in.


Dans les secteurs industriels de l’énergie et du transport, les structures mécaniquessont soumises à de forts niveaux de contraintes dynamiques qui impactent grandement leniveau de durabilité de ces dernières. Dans un contexte de réduction de coût de possessionet d’extension de durée de vie, les industriels sont conduits désormais à bien maîtriserla fiabilité mécanique de leur produit. Pour ce faire et de part la nature stochastiquedes chargements dynamiques, les méthodes utilisées sont celles de la fatigue vibratoire,basées sur des représentations fréquentielles, tant au niveau du schéma modal de lastructure, qu’au niveau de la définition de ses processus d’excitation et de contrainte.De ces considérations techniques, le présent article fait le tour des méthodes de calculutilisées en fatigue vibratoire et compare les méthodes de comptage Peak-Valley (PV) aveccelles du RainFlow Counting (RFC), reconnues comme les moins conservatives et donc lesplus pertinentes, en terme de prédiction de durée de vie. En ce qui concerne les méthodesPeak-Valley, les modèles historiques de Rice [S.O. Rice, Bell Systems TechnicalJournal 23 (1944) 282-332; 24 (1945) 46-156] et deMiles [J.W. Miles, J. Aeronautical Sci. 21 (1954) 753-762],développées en 1944 et 1954, sont pris comme référence et comparés aux modèles RainFlowCounting de ces dernières années. Pour ce faire, l’étude comparative se basera notammentsur les approches empiriques de Wirsching-Light [P.H. Wirsching, M.C. Light, J.Structural Division ASCE 106 (1980) 1593-1607], et semi-empiriquesde Dirlik [T. Dirlik, Application of computer in fatigue analysis, Ph.D. thesis,University of Warwick, 1985], développées respectivement en 1980 et 1985.

The instrumentation of an industrial vacuum arc refining furnace (VAR process) has allowed for the first time to visualize the electric arc during the remelting of a zirconium alloy. This device, recording fast video observations in synchronization with the high frequency voltage changes of the arc, has been applied to the study of the behaviour of the arc and of the transfer mechanisms of the liquid metal to the ingot. Results are given for current densities of about 10 to 20 A/cm2 and arc lengths smaller than 6 cm.

Le projet PREDIT CRISFIS (financé parl’ADEME) consiste à étudier conjointementles aspects crissement et fissurationdes freins à disques haute puissancepour le ferroviaire. Dans cet article,les avancées concernant la partie fissurationsont abordées. Une démarche expérimentaleet de modélisation est adoptée dans le butde mieux comprendre la fissurationdes disques. Des essais de freinage réaliséssur banc d’essai industriel à l’échelle 1sont présentés. Dans un premier temps,l’influence du type de garniture surle chargement thermique vu par le disqueest étudiée au moyen d’une camérade thermographie infrarougeet de thermocouples implantés dansles garnitures et dans le disque de frein.Dans un deuxième temps, les chargementsthermiques extraits des filmsthermographiques sont utilisés commedonnées d’entrée pour des calculsthermomécaniques. Enfin, les résultatsdes modélisations et des essais sont corrélésaux endommagements observéssur les disques.

The recent decrease in Blast Furnace production as well as changes in raw materials andprocess conditions has produced an increase in the silicon and phosphorus contents in hotmetal. This situation increases the probability of slopping and fume emissions duringconverter blowing because of the large volume of highly viscous slag. To carry out thesilicon oxidation and dephosphorization steps, a double slag practice has to be used. Thefirst slag is rich in silicon and phosphorus and has a low basicity. The first slag isremoved. Then the second slag is formed; this low-viscosity slag is subject to the strongagitation created by a high decarburization rate. The second slag is characterized byhigher CaO and phosphorus contents. These conditions yield a better dephosphorization atthe end of the blow. In order to implement the double slag practice, the converter controlsystem was modified. The changes included the design of the lance blowing pattern, theflux additions, the static control, and the logic of the gas collection and cleaningsystem. For a silicon content larger than 0.60% in the hot metal, the results show asignificant reduction in the fume emissions and in slopping, a lower flux consumption, andopen up the possibility of working with iron ore with higher phosphorus content.

For over a decade, Continuous Casting has been a maturetechnology that has prevailed in the steel industry. ConventionalCC is still undergoing small but deep and subtle transformations.Thin Slab Casting is developing at a rate commensurate with theneed of new capacity. Strip Casting has been limited to industrialpilot lines, although commercial implementations have beenannounced. In the perspective of the changes that the steel industry will haveto undergo in the 21st century (control of Greenhouse Gasemissions in particular), continuous casting will be one of theinvariants to provide a degree of stability. Indeed, solidification willmost probably continue to be performed on continuous casters.

For a HIP operation, conventional control of the process variables (T, P) is the current mode used. The process variables follow a prespecified trajectory (schedule) assumed to lead to the final quality of product. A second mode is advanced control, where on-line measurements of a product state variable enable to monitor the evolution of the product variables and if necessary to compute corrections to the schedule in order to obtain the desired quality of the final product. HIP advanced process control requires continuous monitoring of the sample density during all stages of the process and the on-line identification a process model. To this end, a dilatometer has been built for in situ monitoring densification during a HIP operation, the Ashby process model has been validated and on-line identification has been demonstrated. It is shown that advanced process control of a HIP operation can be performed in two steps : on-line identification of the process model and subsequent process path replanning. The first step can only be performed during the process variables plateau of the preset temperature-pressure cycle, and process path replanning consists of a new temperature-pressure plateau.

The optimized overall control system developed by VAI for sinter plants integrates mathematical models and artificial intelligence. It features a process information system and a collection of on-line process models. One group of models is used for the control of sinter productivity and the other group for the control of sinter quality. The setpoints calculated in that way control the sinter plant operation directly. The different modules included in the system are described in the case of the Wuhan Iron and Steel Co. sinter plant in China.

Principle and technological design of electroslag continuouscasting (ESCC), including bifilar mode, T-shaped mould andmetal level detecting system are detailed. Remelting is carriedout for a Cr18Ni9Ti stainless steel with ESCC. The surfacefinish, chemical composition, macro and microstructures, andinclusions of remelted billets are characterized. ESCC reducescost and increases productivity in comparison to the traditionalESR, while achieves comparably excellent products.

Les métaux liquides sont envisagés pour des applications très variées comme les cibles de spallation, les réacteurs nucléaires de génération 4 ou les futurs réacteurs de fusion. Des recherches sont actuellement menées sur l’interaction des aciers, seuls matériaux de structure compatibles, avec les métaux liquides comme l’eutectique plomb-bismuth ou le sodium. Dans ce problème de vieillissement des matériaux, on s’intéresse tout particulièrement aux problèmes de corrosion, de mouillage et de rupture induite par l’interaction avec le métal liquide. Cette revue reprend quelques éléments de la compréhension actuelle des ces phénomènes.

A new automated system installed in the ArcelorMittal Asturiassteel plant in Avilés, based on novel image treatment, aimsat performing an on-line inspection, with feed-back to theprocess, verifying the effectiveness of scarfing. It detectsremaining defects as well as new ones introduced by thisoperation, thus allowing a quick and reliable assessment offinal surface quality.

Nowadays, finding ceramic materials with good physical-chemistry characteristics to makeceramic cups is no longer a big difficulty. However, the stability of the construction,the anti-penetration ability and the adaptability of the working profile of the hat faceof the ceramic cup are of critical importance to prolong the campaign life of the ceramiccup itself and thus the BF hearth. In a lot of cases, the so-called “ceramic cup” isformed just by one, two or more rings of the standard-shaped ceramic bricks which areinstalled closely against the carbon hot face. In these linings, there are manypenetrating linear joints from the hot face to the cold face through the ceramic lining.Both the overall stability of the construction and the anti-penetration ability of thelining are very poor. Therefore, the goal of installing a ceramic cup, to protect thecarbon lining from the erosion of hot metal, would be difficult to achieve and thelifetime of the ceramic cup would not be long no matter what excellent materials werebeing used. However, an “Integrated Ceramic Cup” structure for the BF hearth is composedof special-shaped ceramic blocks which are all interlocked with each other. In such aconstruction, there is no linear breakthrough joint from the hot face to the cold face ofthe ceramic lining. A ceramic lining with this structure can effectively avoid hot metaland gases penetrating into and then through the joints of the ceramic lining to attack thecarbon lining behind. As a result, the campaign life of the BF hearth, and also thecampaign life of the blast furnace, would be prolonged. Nowadays the “Integrated CeramicCup” structure has been used in many modern blast furnaces and its significant performancehas been proved.

In this paper an extension of the sintering method at atmospheric pressure, already used for tool steels, is proposed for prealloyed duplex stainless steel powders. A wide temperature range is tested and the effectiveness of boron as activator of the process is investigated. In all the samples no evidence of liquid phase is observed ; the sintering process allows full density in case of no boron addition and it occurs by solid phase diffusion, enhanced by the presence of two phases, austenite and ferrite : this makes needless to add boron as activator. We obtain density and hardness values comparable with the “as-cast” ones, isotropic phases structure and γ/δ ratio of about 50/50 for the best sintering temperature (1150 °C).

The results achieved with the COREX plants presently in operation show that this technology is a true alternative to the conventional blast furnace. With the experience gained from these plants, continuing developments have been made for the COREX process itself (recycling of steel plant wastes and use of other raw materials), for the equipment design and in the area of investment costs and profitability.

A laser-welded blank (LWB) offers several notable benefits including decreased part weight, reduced manufacturing costs, increased environmental friendliness and improved dimensional consistency. However, in order to take advantage of these benefits, designers need to overcome the formability of LWBs and be able to accurately predict the LWB forming characteristics early in the design process. We present a new approach to predict the maximum elongation of the laser seam; for example, for Advanced High-Strength Steel (AHSS)-based LWBs. This approach is based on a coupling model taking into account the thermal, metallurgical and mechanical phenomena. A comparison of numerical and experimental results shows very good agreement. These approaches offer a considerable advantage in obtaining the formability limits for all configurations.

Polypyrrole films are electrodeposited on zinc and other common metals in a one-step process by using a salicylate salt in a pH 5 aqueous solution of pyrrole. This electrolyte passivates the substrate and makes it possible to obtain strongly adherent PPy films, with controlled thickness by electrolysis at constant current. With this technique, the current efficiency is high and the deposition rate is high enough to be compatible with the imperatives of industrial production (2 μm in 3 s with a 200 mA/cm2 current density).

A novel rheo-rolling process for producing A356 alloy sheet was developed. The influenceof parameters on the microstructure of A356 alloy sheets was investigated. The eutecticfraction and primary α globule size increase with the increment in theroll speed. The globule size and eutectic fraction of A356 alloy sheet increase with theincrement in the casting temperature. The primary α globule sizedecreases and the solid fraction increases with the increment in vibration frequency from30 Hz to 80 Hz. With a roll speed of 0.069 m.s-1, a casting temperature of 660°C, and a vibration frequency of 80 Hz, A356 alloy sheet with a cross-sectionsize of 4 × 160 mm was prepared. The microstructure is mainly composed of fine sphericalor rosette α globules, and the average α globule size is20.5 μm. The ultimate tensile strength of the A356 alloy sheet was 260MPa, and the elongation to failure was 7.9%, which were 2.5 and 3.7 times greater thanthose of the as-cast material.

The mechanical properties of a CuCr1Zr alloy were measured with the help of a Gleeble3500 machine at temperatures ranging from 250 °C to 1000 °C. Some tensile tests were alsoperformed at 20 °C. The measured data were first used to determine the thermal linearcoefficient at different temperatures. The measured curves were then simulated with anelasto-visco-plastic constitutive model assuming that the material behaviour wasisotropic. This law requires the knowledge of temperature dependent parameters that weredetermined by inverse method. This work represents a part of a PhD study on hot tearingsusceptibility during welding.

A goniospectrophotometer is used to analyze the back-scattered light, in the visible range, by a 0.3 cm2 surface. The measurement is non-destructive, without contact and can be implemented in situ. For a metallic surface, the reflected intensity is measured as a function of the back-scattered angle. The probability density of the normal to the surface is then deduced. The ratio roughness r.m.s. / correlation length is calculated. The method is applied to characterize the different techniques for gold backgrounds in primitive European paintings. For a non-metallic surface, the reflected intensity is measured as a function of the wavelength. The spectrum is compared with a data bank of mineral pigment spectra. The comparison allows to identify pigments and, moreover, to deduce the surface state of the painting layer. Examples of Egyptian and modern paintings will be presented.

The innovative technological solutions by VAI (VOEST-ALPINE Industrieanlagenbau, Austria), which are presented, allow to obtain substantially improved results for profile and flatness of hot rolled strip. These solutions concern, on the one hand, the design of rolling stands and rolls and, on the other hand, highly modern numerical models for the control of the important parameters.