As part of a complete theoretical description of the behaviour of the electric arc in the vacuum arc remelting process, a model has been developed for the column of plasma generated by a single cluster of cathode microspots. The model aims in particular to calculate the distribution of thermal energy transferred by the plasma to the surface of the anodic melt pool. The theoretical approach combines a kinetic model, taking into account the formation of the plasma in the cathodic region, and a hydrodynamic model, describing the expansion of the plasma in the vacuum between the electrodes.

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.

Eko Stahl installed a roll gap lubrication system in stands F2-F4 of its HSM in 2001. The main objectives were energy saving, reduction of roll wear and vibration. The paper describes the equipment and its startup, the consequences of roll gap lubrication, looper angles and AGC, the cost saving results by energy saving and roll wear reduction. The influence on surface quality and environment is described as well as the ongoing optimization process.

After transfer to the P.R. of China and modernization in many respects of the installation of a former German steel plant, the Chinese steel producer Shagang will also be able in the future to make high quality flat products. Many important modernization projects are carried out by VOEST-ALPINE Industrieanlagenbau (VAI, Austria). In the case of the hot strip mill, these projects concern in the first place the implementation of high standard technical solutions for rolling technology, automation and process optimization.

In order to roll thin and wide material of very high strength grades on our low powered mill, a global optimization of the process has been done. Taking account of the finisher power limit and furnace maximum drop out temperature, improvements have been made on the thickness of the transfer bar regarding the load of the prefinishing stand, on the finisher speed schedule and preset, on the use of the cooling system and on work roll lubrication.

Mechanical properties models and the development of new control tools and methods induce radical changes in the activity of metallurgy quality technicians with regards to product qualification and allocation on the production lines. The conclusion of these projects enables the metallurgists to summarize on a work-friendly and interactive interface all the data required for qualifying the product with the greatest reliability in terms of surface finish, mechanical properties, product and process critical parameters, special instructions, and thus to take the best quality decision possible.The development of these skills leads to an important reduction in the number of off-line tests, and a faster product release, which improves lead times and limits the stock levels. Finally and above all, the warnings on product and process increase our reactivity on the whole production process and contribute to the improvement of our internal and customer quality results.

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 production of new steel grades - such as dual phase and TRIP steels - requires improvements to both process and equipment of continuous galvanizing lines. In particular, progress has to be obtained in cooling technology in order to get the desired mechanical properties. This paper presents a study of design parameters allowing the optimization of fast gas multi-jet cooling systems. The thermal study involves the application of infrared thermography and three-dimensional numerical simulations. Furthermore, a dynamic study is performed in order to reduce steel strip vibration.

The paper has compiled the actual status for grades X80 and X100 from a point of view of a plate manufacturer. An outlook for a possible extension of feasibility and further development is also given. It can be summarized: 1) plates for gas transporting pipes with strength level of grade X80 are nowadays available up to 25.4 mm and can be produced with the same reliability and reproducibility as lower grades; 2) extension of grade X80 to higher plate thickness even in combination with very low design temperature is practicable; 3) during development stages of grade X100 different approaches has been applied. The current preferred approach to produce plates for pipes with design temperature of 0 °C makes use of a low carbon content in combination with a medium carbon equivalent. So called HACCII process is applied to produce these plates. Plates in thickness up to 20 mm for pipe diameter up to 3611 (~914 mm) have been produced with adequate properties; 4) further development is required and started to extent grade X100 to higher thickness, higher pipe diameter and lower design temperatures.

A major evolution is in sight in the area of packaging steel. After a period of twenty years of continuous improvement of organic coatings for packagings, mainly those applied by varnishing, a totally new process for the coating of steel is under development : extrusion coating. This paper explains the stakes, the fabrication method and the evolutions of these new steel packagings, which will soon be present in our daily life.

Ultra-high strength steels with a tensile strength of 1,000 MPa to 1,200 MPa have been used for bumper and door beam since 15 years in Japan. Recently, it has been tried to apply these steels to reinforcements such as B-pillars inner and so on. The application of these types of steel tends to spread. Their formability, weldability and fatigue properties are described. Formability of ultra-high strength steel is different from that of mild steel, and it is governed by local elongation or stretch flangeability that can be evaluated by bendability. Local elongation or stretch flangeability has a negative correlation with total elongation. When strength exceeds 1,000 MPa, delayed fracture tends to occur. However, when measures to avoid delayed fracture are taken, there are no application examples of ultra-high strength steel sheet with 1,500 MPa tensile strength restricted by the danger of delayed fracture.

The Young's modulus (E) of steels varies with their chemical composition, the manufacturing conditions of the products, the orientation ot the test samples within a given sheet. The knowledge of its exact value is important for the optimum choice of the steel grade best suited for the production of structural parts. Several methods are available for the determination of the modulus of elasticity. At LEDEPP, a tension test method is used, but it is considered that a method based on the measurement of the resonance frequency should be advantageous. As it is a non-destructive method, various research directions can be explored, like the variation of E with orientation, temperature or prestrain. Both methods are described and their results compared.