Based on a model of microstructure evolution, an appropriate rolling schedule has been worked out to produce ultrafine grained steel (2 to 5 μm) on the hot strip mill. This rolling schedule is characterized by a large reduction in the finishers followed by strong cooling. Implementing such a rolling schedule on a conventional HSM raises major problems: increased rolling torque and force, lowered crown and shape control, disturbed looper control, accelerated roll damage, increased slip between strip and roll, insufficient cooling efficiency. These problems have been solved on the new Nakayama HSM by introducing innovative processes such as: single roll drive with different diameter and a new CVC, curtain wall cooling in the finisher, low inertia hydraulic looper, new high-speed steel rolls with solid lubrication.

The coke plant/blast furnace will remain dominant for the production route from iron ores to crude steel.There exists a community of fate for the coke plant and the blast furnace as blast furnaces cannot be operated without coke for physical reasons. For cost optimization, it was and is important to minimize the coke rate in the blast furnace and to utilize the by-products of the blast furnace and of the coking plant. The paper discusses, for an interconnecting network of an integrated iron and steelworks, the potentials of the use of coke oven gas and blast furnace gas. The coke oven gas can be utilized for electric power and heat production, for conversion into hydrogen and methanol as well as reducing gas in the blast furnace or in a DRI plant. Blast furnace gas can be used conventionally for blast heating, coke plant underfiring and power production, or it can be recycled to the blast furnace in the nitrogen-free blast furnace process and in the plasma heated blast furnace process. A critical comprehensive assessment is also given for these potentials with respect to CO2 emissions.

Companhia Siderurgica de Tubarão (CST) No. 1 blast furnace has been in continuous operation for 21 years, accomplishing a high operational performance with high productivity and low fuel consumption. Seeking its biggest challenge of 18,500 t/m3-IV of productivity, several jobs have been developed in order to extend the furnace campaign until 2008. This paper shows the results of these activities and proposes a different concept of hearth wear.

Phenomena that occur at the meniscus in the CC mould have a major effect on product quality. The mechanism of slag rim behaviour and flux infiltration are reported based on the results of industrial characterization and of fluid dynamics modelling of the effect of oscillation and shell velocity.
Lubrication stability is not established as the slag film happens to be broken down and renewed several times during casting. A mechanism of slag infiltration is put forward and the main factors for oscillation marks formation are pointed out.

In 2004 it was timely to reconsider the personality of Jean RIST (1900-1944) who, sixty years earlier, was at the origin of the foundation of IRSID and who gave his life for the liberation of his country. This paper recalls his career from 1923 to 1943 at the “Établissements Jacob HOLTZER”, his active contribution to the “Cercle d'Études des Métaux” of Saint-Étienne right from the creation of this association, his commitment at the “Comité d'Organisation de la Sidérurgie” in 1943-1944 for the draught of the founding principle of IRSID, his participation to the “Résistance” until the sacrifice of his life. This paper should incite to meditate on the example of this visionary engineer, deeply concerned with research in industry and of this idealistic citizen, a man honored by SF2M by the creation of the Jean RIST medal.

Basically different blends are prepared in the Arcelor coke plants that incorporate coals of various ranks, LV, MV, HV, non-coking coals. A comprehensive comparison of these coal blends, within the Arcelor coke plants, has been performed using two successive approaches : characterization of each blend at laboratory scale ; coking tests performed in the CPM 400 kg Movable Wall Oven. CSR can be maintained to very satisfying values if coals entering in the blend composition are strictly selected as regards factors like rank and ashes composition. Non-fusible components decrease the coking pressure, impair the mechanical indices and the CSR. This limits their incorporation below 10 %. Industrial results confirm the effect of the addition of LV non-coking coals : the pushing forces are reduced, the flue temperatures must be increased to keep the stability of the cokemaking parameters and the coke quality is decreased.

In 2001, the width extension of the strand, with the increase of the pallet width from 5 to 5.5 m, increased the new effective sinter area up to 572 m2. A new ignition furnace was built in order to ensure a nominal production of 21,000 tons of sinter per day at constant quality. The new ignition furnace makes it possible to decrease the total thermal needs by 25 MJ/t of sinter. The safety of the installation is improved and the process control is easier. Total productive maintenance was used from the design to the realization. All the experiments and knowledge were capitalized. This was used for the training of the operators.

In this paper, VOEST-ALPINE Industrieanlagenbau (VAI) presents some of the company's technological developments concerning the whole iron and steel production chain: COREX®, FINMET® and MIDREXTM for production of hot metal, the ULTIMATE electric furnace for steelmaking, DIAMOLD (high speed casting mould), DYNAFLEX (oscillator), the compact withdrawal unit for the continuous casting of billets, as well as rolling stands with highly modern design (“Red ring" cassette-type compact rolling stands) and innovative systems for the rolling of long products (PRS, EBROS).

As regards conditions in the mould, Continuous Casting of 400 mm thick slabs can differ from conventional slab casting. Specific features of thick slab casting are reported, concerning heat fluxes, both integral and local. Local heat flux has been determined through an instrumented mould along with thermal modeling of the copper plate. Integral heat withdrawal data are compared with data from conventional slab casting. The effect of steel composition on integral and local heat extraction has been evaluated and interpreted in relation to residence times in the mould and to the relevant thermal resistances. The influence of tundish temperature on superheat in the mould and on heat removal was quantified. Oscillation mark depth and mould powder consumption have been related to heat withdrawal. Cracking defects were characterized in dependence on mould heat flux densities.

The hot strip mill of Arcelor in Fos has been revamped between February 2001 and July 2002. Positive/negative (±200 tons per side) bending actuators were installed on the four first stands of the finisher. This investment made it possible to further improve the geometry of the products (crown and thickness control), as well as the reliability and productivity of the HSM.

The present work describes some steps made in order to increase the casting speed of low carbon and peritectic steel grades produced in CST machine No. 1, without further investments. Some constraints of casting speed discussed in this work include: metallurgical length, secondary cooling, mould powder and chemical composition. Results on quality are presented, comparing slabs produced under the new proposal and the standard casting speed. As a conclusion, it was possible to obtain an additional production capacity of around 110,000 t/year keeping the same quality standard.

Clean steel encompasses a multitude of concepts that are based on fulfilling customer requests. Clean steel can be produced in many ways depending on the existing equipment and detailed customer demands. A common feature of all clean steel production is tight process control along with continuous monitoring. Quality assurance is essential and it still requires many improvements. There are no specific obstacles to clean steelmaking, as the industrial processes are available, sufficiently understood and controlled. The major issues to be addressed remain disturbances that occur in industrial reality. This asks for continuous improvements in processes and equipment and for further development of quality assurance systems to achieve full control of any possible detrimental effect.

Within the framework of the capacity increase of the Arcelor Dunkirk steel plant up to 6.7 Mt per year, a project of casting speed increase has been carried out, in order to keep a similar average casting time with the new ladle tonnage of 270 t as with the previous one of 250 t. Two axes have been studied: increase of the maximum casting speed (applied for standard Al-killed steel grades); increase of the targeted casting speed for steel grades with high requirements in terms of segregation and internal cracks. This increase was based on the progress achieved in the slab internal soundness control (control of caster geometry and secondary cooling), as well as on an analysis of customer specifications to adapt casting speed to the requirements linked with final product applications.

Salzgitter AG has a crude steel production capacity of more than 8 million tons. Its subsidiary Salzgitter Flachstahl GmbH produces hot strip, thin sheets and surface finished products as well as input stock for heavy plates and sectional steel. In February 2003, Salzgitter Flachstahl GmbH awarded a contract to SMS Demag AG for the supply of a single-strand slab caster including the building portion and all ancillary equipment under SMS leadership. A range of as many as 400 steel grades is cast on the two already existing bow-type continuous casters. The new caster has enhanced the grade range by adding in particular phosphor-alloyed and high-tensile steel grades, including HIC resistant as well as IF and C steel. This caster had to be designed in such a way as to be suitable for taking over production of one of the two existing casters in the longer term. Other goals of constructing a new, third slab caster were to increase the annual production rate of all three casters to a total of 4.7 million tons, to cut production costs, to improve the product quality and to safeguard slab production during the standstill and scheduled maintenance of one of the existing casters.

Apart from installation of new batteries, there exist other options for keeping respectively increasing the production capacity of a coke piant. Economic and environmental requirements have to be taken into consideration ieading to very simple solutions such as heating up of old batteries which have been cooled down followed by partial hot repairs, through-wall repairs and pas up rebuilds. Modernizations with regard to anchoring systems, heating conditions and reduction of typical emissions may be implemented in most cases.

The operation of blast furnace No. 2 started in July 1998, raising the CST yearly hot metal production from 3.6 Mt to the present level of 5.0 Mt. In July 2004, after a 6 years long operation, blast furnace No. 2 cumulated a production of 8.16 Mt, moreover ensuring good performance. The paper presents the actions that have been taken to control hearth wear, while sustaining high productivity and low fuel consumption. The results obtained are submitted to a detailed analysis with appropriate reference to the approach that has been followed and the controls that have been implemented.

Clogging of Continuous Casting nozzle has a detrimental effect on productivity and product quality; it also increases production costs and goes against security. Many factors contribute to the clogging phenomenon, including the detailed process parameters of continuous casting and secondary metallurgy. Clogging can be effectively limited by Argon injection that is usually performed through the stopper rod. The nature and quality of the refractory equipment is another factor that must be considered carefully. The clogging mechanism has been clearly ascribed to the level and nature of non metallic inclusions, thus to the secondary metallurgy process. Effective counter measures that have been successfully implemented in Arcelor to achieve long sequence casting are presented.

A new on-line guidance tool has been implemented to help the mill operator with the achievement of a thickness performance that meets the ever more stringent requirements for DWI material. The tool makes it possible to analyse the causes of thickness defects that are originated by the HSM or by the tandem mill.