Mechanisms of deformation in an age-hardenable Ni-Mo-Cr alloy containing large precipitates of the coherent ordered phase were investigated. The dominant deformation mechanism in the examined alloy depended on the applied amount of strain: for low strains micro-twinning within the ordered precipitates and dislocation slip in the matrix prevailed; at higher strains the f.c.c. twinning became the major deformation mechanism. Micro-twinning within the ordered phase was size related - micro-twins occur in large precipitates at relatively small strains. Twinning within the ordered precipitates may occur in all possible twin systems. Ten out of twelve possible twinning systems lead to the formation of true twins, and the long range order is preserved in the twinned regions. Formation of shear bands at high strains destroys the long range order.

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 cracking behaviour of the oxide layer formed during hot rolling was studied togetherwith different combinations of process parameters in order to find their single influenceon the surface quality and formation of oxide defects. Several trials were performed onthe CRM pilot line to study in detail the impact of strip reduction, strip temperature,entry scale thickness, roll degradation, lubrication, skin cooling, chemical compositionand humidity on the scale behaviour. In general, the degree of deformation, entry scalethickness and rolling temperatures are the most important parameters and the importancedecreases in that order.

Fluid flow phenomena are very closely related to the casting quality and surface finish of the cast part. In addition, the good quality of the casting product can be achieved by using an optimum gating system design. In this work, a vortex well, which is one of the important components of gating system design, is utilized in order to demonstrate its effectiveness in improving the mechanical and microstructure properties of the cast part. An X-ray radiography test was performed in order to investigate the porosity distribution in castings with different vortex well dimensions. The scatter of flexure strength results was quantified by Weibull statistics. Microstructure analysis was conducted by using a scanning electron microscope (SEM) to examine the microstructure of selected casting specimens produced from the vortex well design. By optimizing the vortex well design, porosity inside the casting was significantly reduced, while the mechanical strength and reliability of aluminum casting were further enhanced.

PARE has developed an electrode wear monitoring system. Theyhave implemented such systems at the three electric arc furnaces(two DC, one AC) located in Luxembourg. The goal of these systemsis twofold: first it allows the steelmaker to continuously monitor itsgraphite consumption and relate it to the furnace operating conditions;second it allows a feedback to the electrode suppliers for qualitymonitoring.

The structural durability of welded structures is determined by theinteraction of different influencing parameters like loading mode,spectrum shape, residual stresses and weld geometry amongothers. Examples from plant, offshore, transportation and automotiveengineering show how these parameters influence the fatigue lifeand to what extent they are considered in design codes.

The projects of Arcelor innovation R&D aim at developments having a time to market from a few months, for the most advanced, up to the end of the decade, for the most futuristic. They are carried out in partnership with the automotive industry. Ultra-high strength steels are a recent major innovation. They offer an effective answer to the request for improved safety and reduced energy consumption and contribute to sustainable development. The author introduces three major innovative developments: new technologies for high strength steels implementation, new openings for an improved cost/weight saving balance, new surface properties, based on nanotechnology. It is the ambitious claim of Arcelor, now and for the future, to afford steel solutions for all purposes, in particular for the automotive industry. The Arcelor-Nippon Steel collaboration makes it possible to bring an even better answer to the request of customers for further developments.

Laser irradiation may alter the colour of certain pigments used in artworks. Owing to the increasing use of lasers in artwork conservation, this problem becomes extremely crucial especially in the case of a polychromy covered by environmental encrustation. X-ray diffraction analysis and optical microscopy were used to study the crystalline structure of selected irradiated pigments in order to identify the changes that take place upon laser irradiation. Two representative pigments were studied, cinnabar (HgS) and lead white (Pb(OH)2 2PbCO3). The results revealed a change in the crystalline phase or chemical composition, respectively, which can be barely detected owing to its superficial character, which is of a sub-micrometer scale.

The corrosion risks in a wet flue gas desulphurization systemenvironment are reported. Uniform and localized corrosionresistance of different stainless steels is studied by electrochemicaltests. The effects of chloride content, fluoride content, pH andtemperature on corrosion resistance are discussed. The results showthat duplex UNS S32205 or superduplex UNS S32520 gradesare prime substitutes for austenitic 317LNM or super austenitic likeUNS S34565 grades in many aggressive environments. The lifecycle costs of scrubbers constructed of stainless steels plates or cladplates are compared. The excellent corrosion resistance of duplexand superduplex stainless steels, combined with their increasedmechanical properties and moderate alloy cost afford very costeffective solutions for wet flue gas desulphurization.

A fast-computing model for crown and flatness in hot strip rolling and plate rolling has been developed based on steady-state elastic-plastic finite element simulations and an elastic buckling analysis. A single, geometry-independent tuning coefficient needs to be identified for each steel grade family. As a result, the model can be efficiently tuned to production mills. Implementation into the set-up environment “CID” of the SOLLAC Méditerranée hot strip mill is presented.

X-ray diffraction contrast tomography is a non-destructive technique for the 3D characterisation of polycrystalline microstructures containing up to a few 1000 grains. The sample is illuminated with a monochromatic beam of high energy synchrotron radiation. As the sample is rotated, and as grains pass through alignments for Bragg diffraction, diffraction spots are recorded on a 2D detector placed close behind the sample. The diffraction geometry is used to assign spots to the grains from which they arise, and to determine the crystallographic orientations of grains. The spots are used as projections of the grains to reconstruct the grain shapes. The technique has been applied to several materials science investigations in stainless steels, including the 3D characterisation of grain boundary networks, and in-situ studies of intergranular stress corrosion cracking.

Frequently, it is desired to preserve the original tones of copper, brass and bronze surfaces which are used in decorative areas. This can be achieved by applying clear protective coatings, acting as weather barriers and surface protections against mechanical aggressions. The performance of two clear coatings and a hard coating is evaluated, using a linear scratch test and abrasion tests. The hybrid sol-gel coating greatly improves the wear resistance of brass. The corrosion-resistant varnish tested has very poor wear resistance. Too thin and porous hard-coating layers have poor corrosion and abrasion resistance. The hybrid sol-gel coating gives the best compromise in terms of aspect, properties and cost.

A new technology for lubricating the work rolls during hot rolling has been successfullytested in the finishing mill of ArcelorMittal Dunkirk. This new technology allows sprayingvery low quantities of pure oil on the work rolls to reduce the rolling forces by up to20% and with an increased efficiency of 50% compared with emulsions. The lubricant was apure natural oil without any additives.

In horizontal continuous casting or in meniscus free continuous casting, the appearance of corrugations or marks at the surface of the cast products cannot be related with the partial solidification of the meniscus of the free surface of the liquid metal, like in the case of the classical vertical continuous casting process. In order to find their origin, an experimental work has been carried on with two different experimental devices. The first one provides solidified metallic samples to be observed and analysed. With the other one, it is possible to directly look at the formation of the skin on the mould during the solidification of transparent organic compounds. Here, we firstly present the results of the observation of the surface of samples cast in very different casting conditions. In a companion paper, we propose a description of the formation of the marks and corrugations in terms of basic phenomena which occur during solidification.

Steel velocity measurement in the mould has been carried out using a Karman vortex flowmeter. The sensor is based on Karman vortex streets, which occur when a flowing fluid encounters a fixed body. A linear relation exists between the velocity of the fluid flow and the shedding frequency of Karman's vortices, therefore by measuring the frequency, the velocity of the fluid flow can be calculated. The system consists of two consumable sensor rods, which are placed at either side of the SEN. With the end plates instrumented with additional thermocouples, it is possible to relate the differential velocity measurement to end plate temperatures.

During the Bronze and Iron Ages, seven metals and about ten alloys were employed in the Western world. The manufacturing processes used by craftsmen (casting, hammering, finishing) for the copper base alloys are examined and discussed from the archaeological and metallurgical points of view. Some results obtained in Burgundy, dating from the 1st century BC to the 3rd century AD, permit tentative conclusions to be drawn regarding workshop organization and mass production.

This Bessemer lecture is a unique occasion for the author to look at some of the issues to which he has been close professionally, with a perspective spanning over three centuries, something that one does not so often have the leisure to do in the Steel Industry. The author speaks first briefly about Sir Henry Bessemer and the dynamic 19th century of which he was such an active player. Then the author skips over 100 years to 1970 and recollects some of the endeavours and achievements of the Steel Industry of the late 20th century, which he witnessed at first hand. There were deep changes of course, but also intriguing continuity with Bessemer's time. Finally, as Technological Forecasting or rather Prospective, the author projects what kind of path the Steel Industry might tread in the future and why. This is done from the viewpoint of an engineer and based on the idea that the core of the Steel Technology is the archetype of a Cumulative Technology rather than a mature, saturated and somewhat passé activity.

The efficiency of automatic flatness control systems in tandem cold mills is mainly based on the accuracy of the prediction models and on the selection of optimum control concepts. BFI, together with EKO Stahl, has recently developed and partly applied advanced flatness control strategies (providing online-adaptation of actuator action to thickness profile information and in-gap process condition towards a fully integrated flatness control of all stands) that are superior to conventional techniques and lead to significant improvements in strip flatness. The present article aims to demonstrate the principles, advantages and results of this work.

Based on the balance equations of mass, partial mass,momentum and thermal energy, the pyrolysis processof non-coking coals using a counter-rotating twin screwreactor (TSR) is modelled by means of commercial CFDcode PhoenicsTM. In favour of good convergence of themathematical solution, a structured, cylindrical-polar gridis chosen. Variable filling and intermeshing degrees aretaken into account by blocking numerical cells in gasdomain and intermeshing domain instead of performingtwo-phase calculations in a body-fitted co-ordinate system.Viscous behaviour of the granular coals is expressed bymeans of a generalised Newtonian fluid and chemicaldecomposition is implemented with aid of distributedactivation energies.

In the last few years, CPM developed a first generation of charging model for coke ovens to improve the uniformity of oven filling and to reduce charging emissions. A new charging model has been recently built to simulate all kinds of charging process with 3, 4 or 5 charging holes and to obtain a more reliable representation of the levelling operation. More particularly, coal accumulation in each compartment of the leveller bar is represented, in order to have a better idea of the gas free space during the levelling operation. By using this model, it is now possible to suppress or reduce coal accumulation in the oven free space during the levelling operation and to obtain a constant and uniform coal profile at the end of charging, without gas emissions.