L’objectif de cette étude est de proposer un critère de fatigue anisotrope pour ledimensionnement en fatigue de pièces industrielles forgées. Des résultats de différentescampagnes d’essais obtenus sur 3 nuances d’acier laminés sont tout d’abord présentés. Uneattention particulière est portée à l’observation et à l’analyse des mécanismes d’amorçageà l’origine du comportement anisotrope en fatigue. Un critère de fatigue probabilistepermettant de tenir compte de la compétition possible entre différents types de mécanismesd’amorçage est ensuite développé. Ce critère permet notamment de tracer un diagramme detype Kitagawa probabiliste.

Un modèle thermique a été développé afin d’identifier les sources de chaleur accompagnantles déformations micro-plastiques intervenant au cours d’un essai de fatigue cyclique.Dans la première minute de chaque palier, un modèle de barre infinie permet de différer laprise en compte des pertes conductives par les mors. Les sources sont identifiées au fildes paliers de chargement croissant, tout en évitant d’entrer dans le domaine deplasticité macroscopique.

The Arab world has been less affected by the financial crisis of 2008–2009 than manyother regions of the world. As an illustration, the apparent steel consumption has beengrowing to a level of 40 to 45 Mt/year, like in China or India but not so fast. The steelproduction is also growing, but is still in the range of 15 to 17 Mt/year: the region is alarge steel importer, around 30 Mt/year. It is interesting to note that this trade is,essentially, between the two sides of the Mediterranean Sea. Regarding the production, itmust be remembered that this area has the special feature of being based on the directreduction of the iron ores through the natural gas-based processes such as Midrex or Energiron (ex – HYL). Steelmaking is carried out inEAF (electric arc furnaces) and it must be noted that, in the Marrakesh congress, theTurkish delegation mentioned that a new company in this country is designing andmanufacturing electric arc furnaces for mini-mills based on scrap. A last point has to bestressed: the diversification of the steel products made in the Arab world. After a timewhere the emphasis was on light long products (reinforcing bars and light profiles), theproduction is now moving to heavy products such as beams and tubes, and flat products.

Deux grandes classes de procédés ont été employées par les forgerons d’aciers dès lepremier millénaire av. J.-C. A partir de deux exemples typiques nous montrons commentl’interprétation des examens métallographiques avec des outils modernes tels que MEB etMEBFEG permet de reconstituer ces techniques. Un échantillon de l’époque mérovingienneillustre la fabrication de lames figurées par multiples opérations desoudage puis forgeage. Un échantillon de wootz prélevé dans une lame du XVIIIesiècle illustre le forgeage du fameux acier fondu de Damas.

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.

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.

Ce travail présente une technique de détection et de suivi de l’endommagement dans lesstructures en matériaux composites. Les mécanismes d’endommagement dans ces matériaux sontcomplexes. Dès lors que l’on souhaite modéliser le comportement d’une structure, il estimportant de comprendre comment celle-ci s’endommage. La méthode optique d’observationin-situ proposée est appliquée au cas d’une plaque trouée.

Because of the importance of lightweight constructions, nowadays other materials are moreand more substituting components which had previously been made of metals. The usage ofshort fiber-reinforced plastics instead of metals seems self-evident in many cases becauseof their high specific strength and the favorable manufacturing processes. For fatiguelife prediction a simulation process was established, which takes into account the fiberorientation and distribution as a result of an injection molding simulation. Hypothesesfor fatigue life prediction of orthotropic materials have been derived from a lot of testson specimens, implemented in the standard fatigue software tool FEMFAT and verified so farwith component tests.

For every mill the ideal roll can be considered as one that can be used in a mill stand indefinitely. Unfortunately for the roll user, such ideal rolls do not exist. One major reason for work roll changes (planned or unplanned) is “wear”. In the context of cold rolling and temper rolling, “wear” primarily refers to loss of roughness and/or surface texture. Another limitation to roll performance is the fact that mill incidents – minor as well as major incidents – inflict damage on the work rolls, requiring redressing in the roll shop. If a major defect is present in a forged roll, e.g. due to a mill incident, catastrophic roll failure may occur in a violent, explosive manner. Improvement of the value-in-use of a work roll implies a superior wear resistance, a superior damage resistance, and elimination of the safety risks associated with explosive roll failures. In order to deal with this in a concerted R&D approach, a consortium of two roll users in the steel industry, a leading roll manufacturer, a high-tech supplier of roll damage detection equipment, and specialised research institutes have joined forces. Cold rolling trials have been performed, using pilot mills as well as industrial mills, with both novel forged HSS work rolls and conventional forged 3–5%Cr steel work rolls. Separate trials have been designed to focus on either the aspect of roughness evolution or damage resistance. Complementary data from various laboratory tests and industrial mill and roll shop data have been collected. Models have been developed for damage evolution in a roll, and for roughness evolution of the roll surface. In addition, novel non-destructive detection systems and sensors have been designed and tested. This paper provides a concise overview of the results achieved.

A novel web-based Decision Support System (DSS) for condition monitoring and continuousimprovement of steelmaking production efficiency is presented in this paper. Productionefficiency was measured and modelled through Key Performance Indicators (KPIs), which areassigned on-line to a single product (coil) and identified at different facilitiesthroughout the integrated route. The systemic nature of the DSS system boosts theintegration of every agent included in the decision chain of the company. It assuresmulti-agent decision convergence and the transformation of process information and expertknowledge into profitable results. The first case study is presented.

Une démarche de développement d’un modèle probabiliste à deux échelles pour la fatigueHCF des aciers est proposée. Elle est basée sur l’utilisation de mesured’auto-échauffement sous chargements cycliques et est validée sur la base de la prévisiondes courbes de Wöhler d’un acier dual-phase pour différents rapport de charge.

In standard diffraction experiments, ensembles of objects are characterized yieldingaveraged, statistical properties (meaningful only if the ensemble is monodisperse).Focused x-ray beams are used here to localize single nanostructures, identifying andprobing individual objects one by one. In a scanning mode, a 2-dimensional image of thesample is recorded, which allows the reproducible alignment of a specific nanostructurefor analysis. The x-ray scattered signal is analyzed and modelled, to give access to theshape, strain and composition inside the single object with sub-micron resolution.Combination of x-ray microdiffraction technique with other micro-probe experiments on thevery same individual object (simultaneous coupling of x-ray diffraction measurements withatomic force microscopy (AFM)) is also shown; we prove the possibility to interact withthe objects and to address elastic properties for individual nano-structures out of anensemble.

Le comportement atypique des fissures courtes peut être, pour une large part, expliquépar l’effet de la fermeture. Toutefois, la détection du niveau de contrainte correspondantà l’ouverture s’avère généralement difficile sinon impossible pour les fissures de petitedimension. Cette étude porte sur la fermeture des fissures courtes 2D dans un acierinoxydable 304L. Pour optimiser la détection des variations de complaisance, une méthodeautomatique a été développée pour analyser les signaux numériques grâce à des méthodes defiltrage. Il est montré que cet outil permet d’obtenir une mesure précise de la charged’ouverture même pour des fissures ayant une profondeur de l’ordre de 0,1 mm. Lesrésultats obtenus permettent de définir l’évolution de la contribution de la fermeture enfonction de la profondeur de la fissure.

Les aciers inoxydables austénitiques non sensibilisés peuvent subir dans l’acide nitrique un type de corrosion intergranulaire (CIG) particulier. Un modèle d’estimation de la durée de vie de ces matériaux dans ces milieux est proposé. Il reproduit de manière fiable les cinétiques de corrosion obtenues expérimentalement.

Production processes of integrated steel plants, mostly based on coal as an energy source, produce about 2 tons of CO2 per ton of steel. As specific CO2 production has to be decreased by 20% in the mid-term (2020), immediate action is required to further decrease the specific energy consumption. The integrated plant is not energy self-sufficient as extra electricity must be bought from outside, but on the other hand, produces an excess of process gas that has to be used within the plant. Optimisation of the use of the internally produced gases is a key issue as either they are burned at the power plant with a conversion yield to electricity of about 40% and often much lower, or might be valued in the plant internal heat exchangers with a much higher efficiency such as  ~90% in the hot stoves or  ~65% or more in the present reheating furnaces. This paper shows that using the high-value coke oven gas as a chemical reactant (for DRI production) leads to significant extra metal production. From a global viewpoint, this extra metal production is almost carbon-free, as it requires only electricity for its manufacture.

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.

Pour améliorer la tenue mécanique à la fatigue polycyclique des matériaux de fonderie, laCompaction Isostatique à Chaud (CIC) peut être utilisée. Elle consiste en un traitementthermomécanique des pièces moulées afin de refermer, complètement ou partiellement, lesdéfauts initiaux qu’elles contiennent. On propose ici d’utiliser des mesuresd’auto-échauffement sous chargements cycliques et un modèle associé pour caractériser legain en tenue à la fatigue apporté par le procédé CIC sur un alliage cupro-aluminium defonderie.

La SDL (Spectrométrie à Décharge Luminescente) est une technique bien connue pourl’analyse élémentaire et le suivi de profils en profondeur des métaux, mais son prix rendbien souvent inabordable son utilisation pour le contrôle des procédés de traitementthermique. HORIBA Scientific a conçu un instrument de Spectrométrie à DéchargeLuminescente – le GD-PROFILER HTP – dédié au contrôle des procédés de traitement thermiqueet proposé à un prix accessible. Ce GD-PROFILER HTP donne les profils en profondeur de C,N (et O) et des autres éléments permettant de valider le traitement thermique effectué, ildonne aussi très rapidement la composition complète des matériaux avant traitement,permettant de contrôler l’alliage reçu. En raison de la durée rapide d’analyse (quelquesminutes), le GD-PROFILER HTP est l’outil de choix pour repérer les écarts au procédénominal et apporter les corrections nécessaires. Des exemples pratiques seront présentésmontrant l’utilisation du GD PROFILER HTP pour le : – contrôle des matériaux entrants; –contrôle des produits finaux, après traitement thermique; – contrôle du procédé detraitement thermique.