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.

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.

The discovery of Duralumin took place in a military context. The Prussian engineer Alfred Wilm had been mandated in Neubabelsberg near Berlin to develop such an improved alloy, the name of which is as much due to the fact that it is hard as to the fact it has first been industrially produced in Düren. International cooperations as well as harsh competitions have accompanied the first researches on this alloy in the beginning of the twentieth century.

From 1998 to 1999, an extremely intensive dioxin measuring campaign has been performed at the sinterplants of Sidmar. More than 500 measurements have been made. Several hypotheses and adsorbents have been tested for the reduction of the dioxins. Process control improvements and the use of burnt lime then allowed reducing the dioxin emissions by 85 % . For a further decrease, it was decided to build an industrial coal injection installation at the sinterplants. The present reduction of the dioxin emissions is more than 95 % and will reach 97 % in 2001.

When introducing a new control paradigm in industry or society one has to accept that it is an evolutionary process where people, methods and processes must develop simultaneously, and this takes time. The recycling of material has been studied intensely for the last ten years using different approaches to material flow analyses, MFAs. They have given a good view of the magnitude of material flows but their use has been limited by lack of relevant data. In the case of recycling, data must be acquired from the practitioners of the trade and in order to get it, the value of the output for them and for society must be proved and visualized. This paper is based on a MFA model developed at KTH for steel flows in Sweden (part of the Swedish environmental research program, the “Steel-Eco-Cycle”). The aim of the work reported on here was to initiate the process of motivating better sampling of data in industry and society for performing MFAs. The KTH model is based on a product-to-product approach for steel, describing the recycling machine. Data is presented in a simplified model for Sweden with total figures and figures per capita. Areas where improvements can be made are identified and ways to “lubricate” the recycling machine are discussed. The main idea is to provide a way of describing flows that can be of use to recyclers and steel producers and form a basis for discussions on improvements. Finally, the underlying model is briefly described and the uncertainties of data are discussed.

New laboratory tests have been developed to characterise thecoke behaviour at high temperature under conditions similar tothose encountered in the blast furnace, especially in terms ofgasification degree. The validity of these new tests has been demonstrated by comparisonwith the modifications undergone by coke in the blast furnace.The latter have been determined by comparing cokes sampledby a tuyere probe with cokes sampled before charging. The results showed only little correlation with the classical coke characterisation indices (I10, I40, CSR), which indicates that they really bring new information on coke properties.

Concevoir une nouvelle filière d'élaboration de l'acier fondée sur l'hydrogène semble prometteur si l'onconsidère les faibles émissions de CO2 qui en résulteraient. Dans le programme ULCOS, cette filière est wecomme une option à long terme, essentiellement conditionnée par l'émergence d'une économie de l'hydrogène.Pour anticiper son possible développement, on a décidé d'évaluer le procédé de réduction directe en four à cuvepar H2 pur et de déterminer ses conditions opératoires optimales grâce à une approche de modélisationmathématique, complétée par des expérimentations adaptées. Nous avons ainsi spécifiquement développé unmodèle mathématique, appelé REDUCTOR, qui simule le procédé et prédit ses performances. Ce modèle estfondé sur une description mathématique détaillée des phénomènes physico-chimiques et thermiques réels. Enparticulier, la cinétique de réduction est tirée d'essais expérimentaux en laboratoire. La version actuelle dumodèle ne tient compte que de la réaction par l'hydrogène mais une extension à la réduction par CO est prévuede manière à ce que ce modèle puisse aussi être utilisé pour simuler et optimiser les procédés de réductiondirecte existant actuellement. Les premiers résultats ont confirmé que la réduction par H2 était plus rapide quepar CO, ce qui permet d'envisager un réacteur sous Hz bien plus compact que les fours actuels des procédésMIDREX ou HYL.

In order to decrease the silica content in 16% Cr ferritic stainless steel, the phases present in deoxidized inclusions were predicted by the FACT model. To decrease the amount of deoxidized inclusions and slag inclusions in the melt, the capacity of alumina absorption was compared using different top slags. In trial tests, the cleanliness of slabs was significantly improved in 16% Cr ferritic stainless steel produced by AOD processes and the number of surface defects of cold coils was also significantly reduced.

SSSA is involved in the Subproject 9 Scenarios, Sustainability,Dissemination & Training, in particularly in the Work Package4. This KPI, developed at SSSA, measures the most importanteffects in the EU/Rest of the World Steel Trade due to theimplementation of a new technology: a quantitative approachhas been used in order to evaluate the EU raw materialdependence from the rest of the world and an approachboth qualitative and quantitative has been used in order tocalculate the variations in the EU competitiveness. An importantconsideration in the development of KPIs is the selection of theappropriate measurement categories. The selection is based,first of all, on the quantification of the European dependencethrough the weight of the non EU supplier countries andthrough the weight of the most important raw materials in theproduction process, then on the measurement of the Europeancompetitiveness. The article describes the methodology andthe algorithms applied in the steel sector. Finally, some resultsare shown and discussed.

High carbon and chromium martensitic stainless steels are used when hardness and corrosion resistance are essential. Their mechanical properties and cold workability are impaired by large Cr carbides formed during solidification. This can be overcome by a nitrogen addition as a substitute for high carbon.Results are reported about 0.080% N addition to a 1.4116 grade (C=0.47%, Cr=14.5%, Mo=0.5%). The new grade offers a better combination of hardness, toughness and corrosion resistance than the three higher carbon grades 1.4109, 1.4112 or 1.4125.

CRM has developed a mathematical model of the sintering process aiming to optimize the latter in terms of both performances and environmental impact. The model is able to simulate conventional sintering as well as original layouts like selective waste gas recycling with integrated desulphurization or steam injection at the sinter bed surface. The results (in particular CO and SO2 emission profiles) have been validated experimentally and also at the industrial scale.

A model for predicting the austenite grain growth during a common heating process including continuous and isothermal heating processes in medium carbon alloy steel 42CrMo was developed. The isothermal austenite grain growth kinetics were studied with conditions involving soaking time and soaking temperature. The time exponent n in the model was obtained considering the influence of the initial grain size rather than simply utilizing Beck’s equation. The results showed that the value of the time exponent n is 3.55 ± 0.30 when the temperature is above 1000 °C, while the value is 8.33 when the temperature is below 1000 °C. When the temperature is below 1000 °C, the pinning effect of carbides contributes to the higher value of the time exponent. Based on the isothermal model and the rule of additivity, a model for predicting the grain growth occurring during continuous heating was proposed. A reasonable agreement between the calculations and experimental measurements of grain size was obtained. According to the model, the effect of the initial austenite grain size on the final austenite grain size during induction quenching was analyzed. The initial austenite grain size has a significant effect on the final austenite grain size. In order to obtain a refined quenched microstructure, it is necessary to refine the microstructure at room temperature.

Most theoretical work on solidification focuses on dilute binary alloys, while thosecommonly used in industry are multi-component with high solute concentrations. Inconcentrated alloys, the diffusion of one component will be inevitably influenced by theothers, which will further affect the rapid solidification kinetics. Assuming localnon-equilibrium at the solid/liquid (S/L) interface and in the bulk liquid, the kineticsof planar interface migration and dendrite growth in strongly non-equilibriumsolidification of Ni-Cu-Co alloys is comparatively studied. It is found that, for planarinterface kinetics, the thermodynamic interactions lead to a non-monotonic tendency of thepartition coefficient of Co with a slightly lowered interface temperature. Meanwhile, fordendrite growth (i.e. curved interface), the curvature effect and the thermodynamicinteractions together result in the non-monotonic variation of partition coefficients. Dueto the lowered dendrite tip temperature as a result of the thermodynamic interactions,larger undercooling is needed for interface migration and the dendrite growth is sloweddown.

Anisothermal and isothermal oxidation tests have been used to establish correlations between growth kinetics, morphological and microstructural evolutions of NiO layers formed during the oxidation of high purity nickel. It is shown that the transport phenomena taking place during the growth of such layers are complex and a growth model is proposed, which takes into account the diffusion of cationic species (in volume and by short-circuits), the transport of oxygen and the interfacial reactions.

The influence of tensile stresses coupled with temperature cycling has been determined on a Cu-Zn-Al shape memory alloy that transforms above room temperature. It is shown that the application of increasing stresses during thermal cycles leads to an increasing martensite stabilization. The repeated thermal cycling with constant stress as well as slow temperature rates increase the stabilization. This phenomenon is attributed to a pinning of austenite-martensite interfaces by vacancies. This hypothesis is confirmed by the comparison of experiments with continuous and with stepwise temperature variations.

They have been applied to the production of plates, beams and bars for bridges, buildings and mechanical equipment. These products are characterized by a great metallographic homogeneity, high strength with minimized scatter, high toughness of the base metal and the welded joints, the possibility to weld without preheating, etc.

The paper aims at giving an overview of galvanizing reactionof steel sheets, highlighting how the solid Fe - liquid Znsystem tends to keep the liquid Zn phase at thermodynamicequilibrium. Reactions occurring with Al free, intermediate Al bearing(typical of GA production), and higher Al bearing (typicalfor GI production) Zn bath are detailed.

The application of mathematical process models for BOF convertersis state-of-the-art for nearly all plants around the world. Such anautomation system may end up in a black box that is not maintainableany more and cannot be adapted to new requirements. Someprinciple experiences and examples from EKO Stahl are presentedto avoid such developments.

Weathering steels are high strength low alloy steels that under normal atmospheric conditions give an enhanced resistance to rusting compared with that of conventional structural steels. The market for weathering steel bridges in the UK is growing exponentially. This paper describes the UK market for weathering steel bridges, highlights the benefits of the material, describes its limitations, and comments on the appearance of such bridges.

The behaviour of argon gas bubbles in the CC machine is described in the present ECSC project involving Irsid-TKS-CSM. Several approaches are combined and compared, namely water and numerical simulations, which show the same trends as observed on products. Process improvements could be defined in relation with the defects linked to argon gas in the tundish nozzles.