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An experimental study has been performed at CRM with impinging burners to heat quickly low carbon steels without oxidizing their surfaces. The thermal performances of various burners (maximum heat transfer of ~370 kW/m2 on impinged surface) were studied and compared to data collected from classical direct flame furnaces. Simulations permit to consider an interesting reduction of furnace size. The surface characterization indicates the possibility to heat steel strip without oxidizing up to 840°C. It would then be possible to anneal steel strips at higher temperature than it is actually performed in the direct flame furnaces.

A new industrial process allowing to reach very high cooling rates in the cooling section after soaking of a continuous annealing line for steel sheets is presented. This process constitutes the successful conclusion of a long term research programme, jointly carried out at CRM and Arcelor Cockerill-Sambre for three years, including laboratory experiments, pilot scale trials and several industrial campaigns. It is running on from developments performed in the framework of the HOWAQ (Hot Water Quench) process. The process successively combines a moderate cooling step (600 °C/s for 0.8 mm thick strips), in boiling water, and a faster cooling step (above 700 °C/s), by impinging turbulent cold water in a box. Its main features are simplicity, resulting from advanced developments, soundness, flexibility and cooling homogeneity. As treated steel products are characterized by improved mechanical properties, outstanding surface quality (corrosion resistance) and exceptional flatness. The process is implemented industrially since the beginning of 2002.

The possibility to produce deep drawing quality - bake hardenable steel grades, by introducing carbon into the strip after its recrystallization, was shown few years ago at the laboratory scale. A closed reactive zone with high contents of CO and H2 was implemented on the CRM's pilot line of continuous annealing and hot-dip galvanizing. The 0.7 mm-thick strip is carburized in less than 15 seconds with C pick-up between 10 and 70 ppm. Developments performed to isolate atmospheres could also benefit to other reactive treatments (nitriding, oxidation-reduction, etc.) aiming to improve the response of high strength steel grades to hot-dip galvanizing. The reactor design, process feasibility demonstration and product potentialities are presented.

The features of the continuous hot dip galvanization are recalled and it is shown that a process avoiding the contact between the strip and immersed rolls would be a step forward. Such a process has been imagined and studied by means of a water model. Tests on a pilot galvanization line have allowed to determine conditions where no contact occurs between the strip and the zinc containing tank. Stable operation is possible for a sufficient range of line speeds and strip tensions. The advantages of this technique are being verified using a pilot prototype.