The hot tearing of aluminium-copper alloys is a serious defect for the foundrymen. The grain refinement of these alloys allows to decrease their hot tearing susceptibility. The aim of this work is to better understand the hot tearing mechanism and the grain refinement action. So, hot tearing tests and tensile tests in the mushy state have been performed. Moreover, a hot tearing model, based on the nucleation and growth of a cavity in a liquid film and taking into account the mushy zone rheology, has been developed.

Ternium Siderar has recently installed a commercial sensor that measures the soundoriginated during blowing. A proper analysis of this signal may give valuable informationabout the slopping tendency of the heat. Data from more than 4000 heats were collected andthoroughly analyzed. The influences of the materials charged and of their compositions onthe slag slopping tendency were investigated. Based on these results, an application toevaluate the risk of slopping for given process conditions was developed.

An expert system model for a fume extraction system has been developed and installed at an electric arc furnace steelplant. Expert rules advise plant engineers of plant abnormalities that could result in fugitive emissions to atmosphere and/or result in excessive energy consumption. Neural network algorithms are incorporated into the model to mimic instrumentation and to analyse general trends. Since the installation of a prototype, significant financial savings have been made.

Strip casting technology has many advantages, both technical and economical. In the Eurostrip project, this technology is applied to stainless steel at Krefeld (KTN) and to carbon steel at Terni (AST). The latest achievements of this technology are presented in this paper. Positive results are reported with respect to casting width, in-line hot rolling, in combination with in-line inductive heating. The technology is ready for industrial application.

Development of metallic glasses is hindered by the difficulties in manufacturing bulk parts. We report on the preparation of glassy alloys using the spark plasma sintering of gas atomized powders. The Zr57Cu20Al10Ni8Ti5 alloy processed has a high glass forming ability. Densification is obtained at the glass transition temperature (390 °C) under high pressure (≈500 MPa). Systematic study of the effect of powder particles size and sintering time is performed through structural and thermal analyses. Local and partial devitrification of the amorphous alloy is detected, resulting from local temperature overshoots. From these analyses, an approach of the spark plasma sintering mechanism of metallic glasses is proposed.

The Ternium Siderar steel plant in San Nicolas, Argentina, experienced a period of singleblast furnace operation in 2006, first due to one furnace’s unavailability, and later dueto the other’s relining. In order to exploit the excess steelmaking capacity, processeswere adjusted to reduce the amount of hot metal needed for the production of a ton ofsteel. The principal changes in the process are described in this paper: an increase inthe manganese content of hot metal to avoid manganese addition in the converter; heatingof scrap; coke additions; increase in pig iron; use of large quantities of SiC or FeSiduring the blow; temperature decrease at the end of the blow. All of this permitted anincrease in slab production compared with the standard process.

Blast furnace models are fundamental tools that interpretmany of the phenomena occurring inside the reactor. Theycan be either diagnosis or predictive, but they requireavailable measurements to validate their outputs. One of theroles of the different R&D Labs of the ArcelorMittal Group is todevelop, validate, apply and continuously improve the modelsfor blast furnace operations and analysis. The users' feedbackis one important key to success.

In order to limit the thermal gradient of plates during quenching and limit flatness issues, it is necessary to control the cooling. This control requires the knowledge of the cooling performances of the cooling device. This paper describes the equipments and procedure we developed for the on-line characterization of quenching. We illustrate the application of this methodology to the quench of Burns Harbor. After the austenitzing furnace, this quench is equipped with 3 cooling sections that have been characterized for several flow rates, for several speeds of plates and for the top and bottom sides of plates. Thanks to the collected data, heat fluxes have been calculated and correlations describing the cooling performances of the equipment have been built. These correlations have been implemented in a thermal model that gives the thermal state of a plate during cooling according to parameters like thickness of the plate, flow rates of the cooling sections, speed of the plate, and temperature after heating. Experimental and numerical results are discussed.

Efforts made since a few years in view of the integration of mechanical laws in numerical simulation now spread to friction behaviour. After presentation of the major laws available in the literature, a method permitting to obtain an empirical friction law is described. The validity of this approach is illustrated through the analysis of the tribological behaviours of three steel sheets: cold rolled, electro-galvanized and hot dip galvanized.

ThyssenKrupp Steel AG has developed a numerical model tostudy the combustion of coal particles which are fed into theblast furnace through the tuyeres. The basic aim is to evaluatevarious coal lance / tuyere configurations and assess theiradvantages or drawbacks for successful operation. In theULCOS project, this model was used to check the feasibilityof some tuyere configurations for the Top Gas Recycling BlastFurnace process, which is especially challenging regardingtuyere design, combustion kinetics and raceway size.


Cet article est dédié à la description de la problématique de la corrosion sous contrainte assistée par l’irradiation (IASCC – Irradiation Assisted Stress Corrosion Cracking). Ce mode d’endommagement est observé dans les structures d’internes de réacteurs nucléaires à eau légère (REL) qui sont soumises à un milieu caloporteur chimiquement agressif et à l’irradiation. Après une présentation de la problématique industrielle liée à l’IASCC, notamment pour les réacteurs à eau pressurisée (REP) où les structures d’internes sont essentiellement en aciers austénitiques inoxydables (AISI 304 et 316), les facteurs contribuant potentiellement à l’endommagement par IASCC et leur effet individuel sur l’altération des propriétés du matériau sont passés en revue. La nature multiphysique du phénomène d’IASCC est ensuite présentée. Les stratégies et les outils mis en œuvre pour développer un modèle prédictif unifié sont ensuite présentés et discutés.

The work presents results of investigations and microstructural analyses for Mg-SiCp cast composites. The metallographic examination shows that the distribution of SiC particles is uniform. Quantitative image analysis of the microstructure shows the magnesium grain size to be smaller and more uniform than in the base metal. The studies at the level of the interfaces suggest that the bonding between the matrix and the reinforcement is of the adhesive type. The presence of the Mg2Si compound in the composites has also been revealed. Additionally, some compounds seem to be present at the SiC/matrix interface. The performed analyses have allowed to propose a model description of the process of the formation of the Mg-SiC composite structure. Mechanical testing has shown that composites have increased YoungÕs modulus and proof stress (R$_{{\rm p 0,2}}$) and decreased impact strength.

The accidental melting of radioactive sources is impossible to prevent completely because some radioactive sources are extremely difficult to detect. When a radioactive source is melted, the people involved have concern for their safety, and there can also be very large costs to the steel plant. The aim of this study, sponsored by the European Commission, has been to give guidance to steel makers on the radiation safety aspects of an incident, and on what measures should be taken to minimize the impact on the steel plant.

Strip rolling processes depend critically on friction and lubrication for process control as well as for strip quality. Pechiney and Usinor companies have therefore joined with CNRS (National Scientific Research Centre of France) to build an ambitious project gathering seven French public laboratories and their own research centres, Irsid and Centre de Recherches de Voreppe. The two major fields of lubrication were addressed: the formation of fluid lubricant films between rough deformable surfaces, and the formation of boundary films (tribochemistry). The final purpose was to derive a model of rolling processes including a predictive, local friction model. This issue and a future issue of Science et Génie des Matériaux present the efforts and the results of this Research Programme Contract "Materials forming: metal - tools - lubricant contact".

The control of temperature distribution across the strip is essential forthe hot strip flatness improvement. Hot strips of Arcelor in Avilès maydisplay wavy edge defects that are generated after the finisher and areattributed to residual stresses introduced by the accelerated coolingon the run-out-table. A first approach has established that the thermaldrop on the run-out-table has a significant effect on flatness, at theedges in particular. Among several systems that may control temperatureat the edges, the edge masking technology has been selected,considering the previous implementation on CSP mills. Wavy edgesare considerably removed or even suppressed on the operator side,while they are reduced but not eliminated on the drive side.

Quality and production of sinter is essential for an appropriateoperation of the blast furnace. A model for the prediction of theburn through point in sintering process is developed in orderto improve the stability of the process. Speed strand, air flowthrough the bed, raw material rates and real thermocouples temperaturesare considered as input variables. The sinter bed is splitinto portions and a set of differential equations (mass and heatbalances) are established in order to obtain a good estimationof the gas temperature at the wind boxes. These temperaturesare compared with the actual measurements and entered into themodel to achieve a typical modern filtered scheme.

For vacuum tank degassing, dynamic process models for dehydrogenation, denitrogenation, desulphurization, decarburization, the course of steel temperature and the removal of non-metallic inclusions were developed. They were validated by comparison of simulation results with measured process data from different vacuum tank degassing plants. The models are applied for on-line process observation, providing the operator with information on the current heat status, which is normally not available during the degassing process under vacuum.

The crash performance improvements achieved by using PressHardened Steel (PHS) based laser welded blanks are reported.The interest of using a dedicated welding process to avoidexcessive AlSi coating dilution is discussed. In-use propertiesanalysis demonstrates the interest of this concept. Case studiesare performed on door-ring and rear rails to demonstratethe strong potential in terms of weight saving and crashperformance.

We propose a model for predicting the kinetics of cementite dissolutionand austenite growth during heating and soaking. This modelis applicable to multi component systems and a good agreementbetween the calculations and experimental data were obtained. Thismodel is coupled with a mechanical module which allows taking intoaccount the various effects of cold deformation on the kinetics ofaustenite formation during heating and soaking. A discussion ismade from a 3D microstructural investigation.

The paper presents the new Mo free duplex stainless steelUR2202 (EN 1.4062) developed to provide a cost effectivealternative to 304L (EN 1.4307), concrete, organic materialsor galvanized carbon steel in potable water systems, pulp &paper industry and construction applications. The reductionof Ni is balanced by a nitrogen addition in order to obtaina microstructure containing approximately 50% ferrite and50% austenite. Several industrial heats were produced with22Cr%, 2Ni% and 0.2N% as the typical composition. Thenew lean duplex grade UR2202 has better localized anduniform corrosion resistance and twice the yield strengththan 304L.