Nanocrystalline oxide ceramic powders are usually metastable and tend to transform into a stable phase during sintering. In this paper dealing with the sintering behaviour of nanosized alumina powders, we present the effects of several parameters on the macroscopic and microscopic behaviours during the pressureless sintering.

In the context of an ever increasing demand for best surface quality of cold rolled strip, the efficiency of visual inspection is becoming more and more important. VOEST-ALPINE Mechatronics has already developed several combined systems based on automatic inspection followed by the inspection by a human inspector. Such systems are operated successfully on different lines at voestalpine Stahl. In this paper, the design features and the operation mode of these systems are described.

Within the framework of a 3.5 million tons production of the Chertal steel plant, the RH unit and the new strand caster will produce about 1 million tons of ULC steel dedicated to automobile body applications. Therefore, some modifications at the RH were decided in 2000. This paper will be articulated in two parts: in the first part, we will present the results obtained with the modified RH installation: decarburization and metallurgical achievements as well as steel reheating capability and performances of the burner. In the second one we will present the new casting working point and focus on the quality results of the RH-CC4 production line.

When welding a zinc coated steel sheet, the associated thermal cycle may activate diffusion and/or alloying reactions between steel and zinc. These reactions develop differently depending on the coating type (electro- or hot dip-galvanized, galvannealed). This in turn determines the chemical aggressiveness of the coating toward its environment, for example the copper electrodes used in spot welding.

The investigation of dioxin formation mechanisms demonstrated that most part of PCDD/F formation occurs in the sinter mix during the sintering operation. This result has a direct impact on abatement strategies of PCDD/F: use ot inhibitors added in the sinter feed and study of the impact of raw materials. Trials carried out on the IRSID pilot pot and on the Charleroi sinter strand have shown that urea addition could be a promising method to reduce pollutant emissions at the sinter strand main stack: PCDD/Fs (about - 50%) and SO2.

Near-net shape beam-blank casting offers substantial advantages in relation to costs, but also product quality. It is an attractive solution for the production of heavy beams and sections. This paper outlines the fundamental desing aspects of beam-blank casting and illustrates the advantages of this technology by means of several examples of VAI-designed and suplied installations.

The civil engineering structures considered in this paper are reinforced concrete structures and cables. Corrosion tests are used to select the steel grades having the best corrosion resistance. Furthermore, electrochemical techniques, like the measurement of the electrode potential and of the polarization resistance, are applied to structures in service to characterize the condition of the reinforcing elements in the concrete.

This report, a conclusion of a VDEh working group, has the aim to show that a 100% inspection at a suitable stage of the whole production line is necessary to reach the “zero-defect”. This work should lead to a better understanding by the customers and steel consumers of the limits, which are achievable with the current techniques in connexion with the discussion about the “zero-defect”.

The paper presents a review of the current knowledge on the influence of gaseous atmospheres, and primarily ambient air, on fatigue crack propagation in metallic alloys. Experimental evidence of the effect of exposure to ambient air or any moist environment on fatigue crack propagation in steels is first proposed. The different interacting processes are analyzed so as to clearly uncouple the influence of the various factors on crack growth resistance. Two distinct mechanisms are identified : the adsorption of vapour molecules and hydrogen assisted fracture at crack tip.

The new tandem mill of TKS was built as a five stand all six high mill and coupled with the pickling line in 2001. TAKO is equipped with a new generation of electrical control system. It guarantees best accuracy for product quality and tolerances right up to the edge of the strip.

Since about 10 years, Usinor has been extensively developing and implementing automatic surface inspection systems (designated as ASIS). Research work enhanced by industrial developments in partnership with Matra, has produced systems capable of detecting and classifying defects according to the expectations of the users. The data obtained are transformed by a computer-aided post-treatment into automatic grading of coil quality and into guidelines to the operator for the evaluation of its compliance with specifications.

Paleocorrosion, a new domain in science of materials, refers to the understanding of the processes of degradation of the “ancient” metal materials. Objectives are to decipher technical, ethnological or simply historic information inherent in them. It is not only a question of allowing their reading, but also to estimate their state of degradation to ensure their durability. The understanding of the deteriorated structures requires physical chemical characterizations (analytical, structural or even functional), often with a high level of performance, according to a very particular approach. The main methods of investigation to study these problems are presented and illustrated with some specific archaeological samples.

Taking into account the mechanical properties of the different materials constituting a weld (mismatch effect) is necessary when dealing with defect assessment of structures with a crack located in a weld or near it. This paper is a synthesis of the work done in the past at Electricité de France on this topic in relation with other works done in France or around the world.

Steel is a universal material and has reached a high level of sophistication in applications and recycling potential. Rules are indicated for maintaining the sustainability of recycling (DfR concept). Consumer goods should be designed so as to maximize metal utilization, which is the only economical solution to meet ambitious recycling levels. The present level reached by recycling in France is compared to those targets in order to identify how much more progress has to be made.

VOEST-ALPINE Industrieanlagenbau (VAI) has erected and started up an ultra-wide slab caster (up to 3.2 m) in Mobile (Alabama) for the North-American steel producer IPSCO Steel. This paper presents the specific technological features and the automation system of this installation, as well as the initial operational and metallurgical results.

Two different approaches are available to reduce the mass of automotive steel wheels. The traditional approach is based on the use of high resistance steels that allows a thickness reduction of the rim and disc. A mass reduction up to 25 % can thus be obtained. A different approach allows a larger mass reduction with a more drastic change in the wheel production technology. One possibility is to use laser welded blanks to feed the existing manufacturing lines. Another possibility is to implement a combined spinning and rolling of the rim. These new steel solutions allow a mass reduction up to 50 %. Indeed they allow adjusting precisely the steel thickness and properties to the local service conditions. Finite elements calculations have been carried out to assess the static and dynamic behaviour of the new wheels.

Discontinuities of microstructure in steels induce stress concentrations. Microplasticity is the plasticity which exists locally at these stress concentrations, whereas the remainder of the material is in the elastic domain. The microplasticity threshold is the nominal stress in uniaxial loading from which microplasticity exists. During fatigue tests, this threshold has been determined for the 304 L stainless steel by measurements of temperature variations, informations derived from hysteresis loops, observations of microstructure at the surface of polished specimens. The microplasticity threshold of the studied material is between 60 and 75 MPa.

A new advanced and breakthrough technology has been developed for hot slab on-line surface inspection and installed in Aceralia (Spain). This innovative inspection system, integrating novel Conoscopic Holography, CCD cameras, a complex mechanical system and intelligent tools, operates in the real environment of a continuous casting facility, allows on-line hot slab surface inspection of 100% of the production, detecting cracks - without removing the surface scale - and inclusions (peeling a narrow strip on the surface).

Discontinuous elaboration or transformation processes treat separate batches of raw materials. The properties of the raw materials may differ from one batch to the other, thus altering the kinetics of the transformation process. When these changes are significant and they are not taken into account by the transformation process, the final product may be unsatisfactory. It is shown that a feedback command is usually not able to restore the requested quality of the final product. A process model that can be re-identified during the operation makes it possible to define the adjustments to the process parameters that will yield a final product with satisfactory properties. In this paper, a feed-forward command based on a linear approximation of the process model is proposed in order to predict the necessary adjustments. This method is much simpler and requires less computing time than the usual non-linear optimization methods, in particular for multivariable processes. As an example, this technique is applied to control a multivariable elaboration process of materials : the hot isostatic sintering of alumina powder.

EISYS is a new optical edge-inspection system for cold rolled strip products. Two cameras examine both cut edges and their indications are used to optimize the edge-trimming conditions without the need of stopping the line or reducing its speed. EISYS has been installed at three different production lines of voestalpine Stahl and has already resulted in significant productivity, quality and cost benefits.