La parution d’un nouvel ouvrage (1) de Gilbert Etienne, très intéressant comme toujours, nous amène, sans évidemment vouloir refaire notre étude de 1990 (2), à faire le point de cette comparaison toujours pour le domaine de la sidérurgie, près de vingt années plus tard.

Construction sector is the major user of Steel, and recycling is very important for the sector itself and also for the Steel industry, as a secondary raw material.
Recycling demonstrations of three building components (steel sandwich panels with polyurethane foam-steel composite structures made of beams, profiled sheeting and reinforcement bars-steel profiles combined with plasterboard partitions) have shown that these steel components are easy to separate and produce a high quality scrap that ensure the profitability of this end-of-life treatment.

The feasibility of increasing proportion of lump ores in blast furnace was investigated. The lab results showed that self-softening and melting properties of the lump ores were dramatically improved by interaction between sinters and lump ores found in the experiments. Furthermore, the collocation pattern of lump ores and ratio between lump ores was optimized according to interaction. When the proportion of lump ores was up to 23% or 27% at the excellent collocation pattern and appropriate ratio, the burdens still conformed to the requirements of ironmaking.

Over the last decades the steel industries worldwide have evolved more or less independently from each other, in the EU and in North America in particular. A competitive comparison of two different Basic Oxygen Furnace (BOF) maintenance operations is presented, discussing various cost figures in a theoretical case study.

The selective oxidation of three CMnSi steels with different C levels was studied by XPS. The formation of a gradually covering SiO2 film is observed until a transition temperature above which the oxide film disappears, resulting in a renewed appearance of metallic iron at the surface. This change in oxidation behavior is thought to be due to the SiO2 reduction by solute C which is thermodynamically favorable at high temperature. At the same time the precipitation of a BN film on the metallic surface was observed which prevented any further oxidation.

High cycle thermal fatigue due to the mixing of hot and cold fluids may initiate cracking in pipes of safety related circuits. A method has been developed to identify such fluid mixing zones subjected to potential thermal fatigue damage. This method is based on a loading model and a mechanical model that depend on the main characteristics of the mixing zone and on the material properties. It is supported by a large experimental program. This method has been applied to all the mixing zones of safety related circuits of the EDF pressurised water reactors, allowing to identify sensitive zones and to apply an appropriate inspection program that ensures the control of the risk due to this damage mechanism.