In the general frame of energy saving, environment protection and the concept of circulareconomy, the fundamental research on the sintering technology with super deep bed,achieving energy saving and emission reduction, was carried out. At first, thecharacteristics of the process and exhaust emission in the sintering with super deep bedwas mastered through the study of the influence of different bed depths on the sinteringprocess. Then, considering the bed permeability and the fuel combustion, their influenceon the sinter yield and quality, their potential for energy saving and emission reductionwas studied. The results show that the improvement of the bed permeability and of the fuelcombustibility respectively and simultaneously, leads to an improvement of the sinteringtechnical indices, to energy saving and emission reduction in the condition of super deepbed. At 1000 mm bed depth, and taking the appropriate countermeasure, it is possible todecrease the solid fuel consumption and the emission of CO2, SO2,NOx by 10.08%, 11.20%, 22.62% and 25.86% respectively; and at 700 mm bed depth, it ispossible to reduce the solid fuel consumption and the emission of CO2,SO2, NOx by 20.71%, 22.01%, 58.86% and 13.13% respectively. This researchprovides the theoretical and technical basis for the new technology of sintering withsuper deep bed, achieving energy saving and reduction of emission.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

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 growth velocity during solidification of an undercooled melt of a Co-Cu alloyprocessed by electromagnetic levitation was measured using a high speed video camera.Applying a model of local non-equilibrium solidification, theoretical predictions ofdendrite growth velocity and dendritic growth radii are compared with high-accuracymeasurements of the growth kinetics. As the undercooling ΔT reaches a critical valueconsistent with the dendrite growth velocity being equal to the atomic diffusion speedVD in bulk liquid,ΔT =ΔT(VD),the velocity-undercooling relationship exhibits a break-point. A distinct change in thedendritic growth mechanism exists with the onset of complete solute trapping andchemically partitionless solidification of the core of the main stems of the dendritesoccurs. A complete transition to the thermally controlled growth of dendrites occurs atΔT =ΔT(VD)that leads to essential changes in the microstructure of dendritic patterns The phenomenonof dendritic fragmentation in Co-Cu melts, solidifying at ΔT <ΔT(VD),is discussed.

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.

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.

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.

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.

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.