The high temperature oxidation behaviour of cast superalloys strengthened by carbides has been studied as a function of their grain fineness and their dendritic orientation near the surface. These microstructural features have both a significant influence on the oxidation kinetics. The effect depends on the nature of the base metal of the superalloy, on the overall chemical composition or on the types of carbides.

Deposition of Ni3P nano-scale layer on B4C nanoparticles in fourcontents of sodium hypophosphite as reducing agent including 5, 10, 15 and 30 g/l viaelectroless coating were done to investigate the effect of reducing agent content on thecoating thickness of deposited Ni3P. The bath pH and temperature was 5.5 and 85°C, respectively and the coating time was 25 min. The powders were characterized bytransmission electron microscopy (TEM) and the phases present were revealed by X-raydiffraction (XRD). Nickel and phosphorous contents of the coatings were measured byinductively coupled plasma analysis (ICP). The results revealed that by increasing thereducing agent content from 5 g/l to 30 g/l the average coating thickness increased from19 nm to 28 nm. Although the increasing effect of adding sodium hypophosphite content waspreserved, there is a critical amount for sodium hypophosphite content to increase thecoating thickness.

Work based on both water model experiments and numericalinvestigations is presented. Basic flow pattern in a continuousslab casting mould adopting a BSP type nozzle is studied bynumerical simulation performed by the in-house code ofVisual Cast II, hiring the k-ε model, with results validatedby water model experiments. The structure of turbulence inthe mould is further studied by LES. The preliminary resultsreveal a certain match on transient flow patterns with thewater model experiments.

Recent studies have shown that in certain situations, usually described by mixed lubrication models, a continuous ultra-thin film could separate two solids, even at the scale of asperities. In this paper, the consequences of this assumption are examined in the case of cold rolling geometries. The tribological behaviour is derived from the resolution of the Reynolds equation. The influence of the rheological parameters of the lubricant and of the existence of a cavitation zone is discussed.

Les aciers inoxydables ferritiques connaissent un développement régulier depuis de nombreuses années, en partie grâce aux variations importantes du coût des éléments d’alliage et notamment du nickel qui impactent fortement le prix des nuances austénitiques classiques. Toutefois, il ne faut pas négliger les avantages techniques que présentent les nuances ferritiques. Cet article présente une série d’exemples illustrant les performances des aciers inoxydables ferritiques dans des domaines d’applications variés et souligne la large gamme de propriétés qui peuvent être obtenues.

A technique, which allows characterizing the local strain field over a domain representative of the microstructure of a heterogeneous material, is described. It is based on scanning electron microscopy, microelectrolithography, image analysis and in situ mechanical tests. On one hand, in relation with a microstructure analysis, it allows characterizing the different mechanisms responsible for the plasticity or the damage of materials. On the other hand, a quantitative analysis allows comparing and validating from a local to a global scale, the different models used for the prediction of materials constitutive laws. Finally, the knowledge of the experimental displacement improves seriously the results of finite element computations, by a better determination of the boundary conditions.

The determination of residual stresses in coatings generally goes with the simultaneous determination of their elasticity constants. The main experimental methods used for that purpose are briefly reviewed and their advantages and limitations discussed: mechanical tests on self-bearing layers or on coated substrates, indirect physical methods.

The initial solidification in the continuous casting process can be controlled by imposing a pulsative AC electromagnetic field on the meniscus. The casting experiment of a steel billet has been conducted by using a commercial billet caster. The imposition of a pulsative AC electromagnetic field has greatly improved the surface qualities. This presentation provides the results of the electromagnetic casting project of JRCM which is supported financially by the Ministry of International Trade and Industry of Japan.

As any other industrial process, galvanizing has its own history and this is the first time that an exhaustive report of it is presented. Protection of flat steel against corrosion by an other metal is indeed a very old process, that goes back to the Middle Ages. The first coated sheet was a tin coated sheet, known as tin-plate, preceding by several centuries the very galvanized sheet.

The studies developed at CST sinter plant in order to point out any factor that may have an effect on plume visibility are reported. Specific software and indexes have been developed. The approach included a retrospective analysis followed by further industrial tests at the sinter plant with different material input (fuels and raw materials). The results are discussed with reference to potential effects on the plume visibility. Further steps are considered to progress the stack plume project.

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.

A new filler material, a stabilized ferritic welding wire, has been developed for the joining of the stabilized ferritic stainless steel sheets increasingly used in automotive exhaust systems. The joints obtained in the GMAW and GTAW processes behave at least as well in service as those obtained with austenitic filler wires. The new welding grade can also be applied to produce heterogeneous assemblies.

A new on-line guidance tool has been implemented to help the mill operator with the achievement of a thickness performance that meets the ever more stringent requirements for DWI material. The tool makes it possible to analyse the causes of thickness defects that are originated by the HSM or by the tandem mill.

High strength steel is an interesting alternative for making steel structures more competitive. Its production and use in Europe is small compared to markets as Japan and USA. It would be of mutual benefit for producers and users if the use increased. The paper gives examples of successful use and a state of art concerning design of such structures. Possibilities for further development and obstacles to be overcome are also discussed.

The influence of long-term ageing in NaCl on the passivity and electrochemical behaviour of UNS S32304 was studied. The passive film thickness, the Cr/Fe ratio and the chloride content were significantly increased after ageing. The chloride distribution depends on residual stresses, the sample microstructure and surface preparation. Local electrochemical measurements revealed that pitting potentials are between 250 and 550 mV vs. SCE after electropolishing. The higher the chloride content, the lower the local pitting potential. It was also shown that the presence of chloride was balanced by the enrichment in chromium after ageing. Then no pitting potential could be measured.

Pour améliorer la tenue mécanique à la fatigue polycyclique des matériaux de fonderie, laCompaction Isostatique à Chaud (CIC) peut être utilisée. Elle consiste en un traitementthermomécanique des pièces moulées afin de refermer, complètement ou partiellement, lesdéfauts initiaux qu’elles contiennent. On propose ici d’utiliser des mesuresd’auto-échauffement sous chargements cycliques et un modèle associé pour caractériser legain en tenue à la fatigue apporté par le procédé CIC sur un alliage cupro-aluminium defonderie.

1 GHz very high frequency acoustical imaging displays a micronic resolution. Owing to its nature of sub-surface imaging, it is well adapted to the characterization of porosity. Used as a means for quantitative measurements through acoustic signature processing, it provides sufficiently localized information to characterize the elastic properties proper to each component of a SiC/SiC minicomposite, the fiber and the matrix.

VOEST-ALPINE Industrieanlagenbau (VAI) has developed the VAI-CON Temp system for the continuous temperature monitoring in metallurgical vessels. The system has been tested for a variety of installations and has reached industrial perfection. It has many potential applications (from the electric arc furnace to the continuous casting tundish) and, thanks to the highly accurate results it provides, it allows a substantially better process control than the conventional, discontinuous measuring systems.

Because of the effects that they produce, grinding operations may modify significantly the surface of a material and change its properties. The major part of the plastic work of cutting is tranferred to the part being ground as heat. In the case of the austenitic stainless steel studied here, grinding leads to an increase in hardness which can be attributed to the superficial plastic deformation of the material. However, for the most severe grinding conditions, a change in the deformation process is observed leading to dynamic recrystallization. This process is characterized by grain growth and dislocation rearrangement under the combined effect of the temperature and the stress level reached during grinding.

Since its introduction in the early eighties, Environmental Scanning Electron Microscopy (ESEM) proved a particularly useful tool in the characterisation of delicate samples mainly in the field of life sciences. Now, the potential of this equipment (no or little sample preparation, possible dynamic observation and reactivity studies...) is more and more employed in traditional materials domains. Some typical applications of ESEM concerning metallic compounds are presented.