Steel slag is historically utilized as road pavement. However, there are many identified cases of problems related to cracks on the roads caused by steel slag volume expansion. In order to solve the volume expansion problem of the steel slag and to guarantee its use as road pavement with quality control even in high technical requirement projects with asphalt layer, Companhia Siderúrgica de Tubarão (CST) developed with a Road Consulting Company a treatment process to fit the steel slag to the characteristics demanded in road construction.

The InterNOx project was carried out over a period of three years from October 2000. It benefited from a financial support by ADEME. The consortium of the project included Arcelor, Stein-Heurtey and Gaz de France. The purpose of this project was to promote the industrial implementation of these new burners in France and in Europe. It will make it possible to reduce CO2 and NOx emissions and to improve the performance of the reheating treatment of industrial products with new prediction models that have been validated on industrial or pilot furnaces.

This paper presents some of the highly modern and innovative solutions used by VOEST-ALPINE Industrieanlagenbau (VAI) to comply with the high quality and productivity requirements set for the stainless steel slab continuous casting machine supplied to the Tornio plant of Outokumpu Oy and started up in September 2002.

A digital system has been implemented on the hot strip mill of CST to record and to collect on-line images of the strip and of the equipments at critical locations. All the data from fixed camera or from “scanning” cameras with extended scopes are displayed through Internet to the HSM operator and maintenance staff. The system is very effective and is a major asset for fault analysis as well as for the on-line strip to strip optimization of the rolling parameters by the operator. The system has allowed deeper investigations at the coil box, at the finishing mill and at the down coilers. Indeed the very intricate nature of fast events that occur at these locations make them difficult to be observed on-line by any operator.

For today's investments, quick pay-back is becoming more important than ever before. The market increasingly demands the shortest possible delivery times and correspondingly greater flexibility of production. Minimal shutdown times as well as a fast start-up curve during start-up or restarting of the plant have become an absolute necessity today. A new plant concept is illustrated by the extension project of an existing Steckel mill with three finishing stands in tandem arrangement to increase its annual production. Furthermore, the quality of the products will be clearly enhanced thanks to the modified process and the selected technology. In order to implement all this with the highest possible commercial benefit, a revolutionary revamping concept, which reduces the mill shutdown period to a minimum, is introduced to the market. The so-called “add on products” have been developed to generate the highest possible benefit in existing facilities with limited expense and effort. Highlights include the differential tension looper and the tensiometer looper, the compact cooling system, edge masking as well as the on-line polisher.

In continuous hot dip galvanizing, in particular with galvannealing baths, competitive reactions occur between iron, zinc and aluminium that may be affected by other elements such as chromium. Based on thermodynamics modelling and experimental descriptions, the zinc rich corner of the quaternary Fe-Zn-Al-Cr system is investigated at 460°C. The results obtained contribute to a better knowledge of the reactivity of steels in industrial galvanizing or galvannealing baths.

The mechanism of zinc wettability defects on high silicon and high aluminium annealed steels has been studied by transmission electron microscopy of specimens prepared from synthetic steels recrystallized on a simulator. Wettabillity defects on high silicon steels are associated with a continuous amorphous silica layer that forms during annealing. On high aluminium steels, wettability defects result from a continuous crystallized alumina layer thicker than 6 to 8 nm.

In continuous hot dip galvanizing, steel strip is immersed in a molten zinc bath containing small amounts of aluminium. A model has been developed describing the kinetics of the galvanizing reactions that occur at the steel/liquid zinc interface (dissolution of iron, heterogeneous nucleation and growth of the intermetallic phase Fe2Al5Znx). The model has been validated using experimental data available in the literature for a three-second galvanizing treatment.

The storage buildings have generally a very high fire load. This leads to impressive fires, which make however few victims. It is difficult to extinguish these fires after the flash over. Not withstanding the designed fire resistance of the structure, structural failure may be expected at some stage of the event. To guarantee the safety of the firemen, the precise type of failure is essential. Collapse must occur in a ductile mode in the compartment under fire. This collapse should not trigger a further collapse of next elements of the structure that are submitted to lower temperatures. Design of firewalls must take into account the interaction of the wall with the structure, that will deflect. Properly designed standard steel structures perform well under fire and make it possible to meet these safety requirements, that have been included in the new French regulation on fire safety of storage buildings (August 2002).

Hot rolling and solution annealing of duplex stainless steels involve high temperature reheating steps in oxidizing atmospheres. The thin scale that forms on the surface is not easily removed because it contains oxide nodules that are deeply embedded in the underlying alloy. These nodules appear when the protective Cr2O3 layer becomes locally inefficient. At the same place, oxidation of iron and manganese is possible and less chromium is needed to develop the scale. Depletion of chromium in the steel beneath the nodule is then less important and pickling the plates becomes more difficult.