A new technique for automatic assessment of centre line segregationbased on image analysis is presented. This innovative tool candetect both centre line segregation and centre line cracks from digitalizedsulphur prints giving an objective result. A data base containingprocess data from the caster and the new index for segregationmeasurement have been created. First analyses of this data base bydata mining tools have been performed showing very promisingresults.

To maximize furnace campaigns and to minimize production downtimesthrough short lining times, the entire integral blast furnacearea, including the auxiliary units, has to be theoretically partitioned.The evolution of measures for extending furnace life is in conjunctionwith the investigation and understanding of the in some respectsvery complicated wear mechanisms and their causes. Of mostimportance are the constructional, material and process engineeringmeasures to reduce wear and the measuring instrumentation forearly detection and progress monitoring of wear.

The main purpose of ArcelorMittal Tubarao skin pass is to improvethe flatness in thin gauges hot rolled strips. Since the start-up in2002 several actions have been implemented and a consistentevolution of quality and process control has been reached:
The philosophy of production scheduling along the rolls campaignto minimize the effect of roll wear;
The definition of optimum target elongations to keep as constantas possible the roll forces and avoid roll bending changes;
The automation of bending forces control according tocharacteristics of the strip and the rolls.

A new 400,000 ton/year 2-stand temper and double reduction mill has started production in April 1999 at Dongbu Steel Asan Bay Works in Korea. This facility produces skin-passed and double reduced tin mill black plates. The line incorporates state of the art technologies including AC motor driven 4-high CVC mills and computer integrated automation systems. The line has the capability of producing products 600 mm to 1,250 mm wide and in gauges from 0.15 mm to 1.0 mm for skin-passed products and from 0.15 mm to 0.36 mm for double-reduced products. An outline and the features of the line as well as the quality characteristics of the products are presented.

Steel rolling technology has achieved such fantastic progress in the 20th century that it might be considered to have come to maturity.Actually, it remains nowadays the object of intense development thataffords further impressive improvements. The progress of rollingtechnology is fostered by a drastic global growth of the number ofrolling equipments on the order of 40% over the last 15 years. Itbenefits from a dedicated R&D effort based upon a large scope ofscientific knowledge. The 9th Steel Rolling Conference illustrates thispotent innovative approach and it offers a unique opportunity forfruitful exchanges between steel producers, equipment suppliersand steel users.

The properties of the well known enhanced steel 12 Cr Mo9-10 are compared with those of the most recent generation of modified CrMoV steels who are characterized by the addition of vanadium. The comparison concerns the base material properties before and after heat treatment, as well as the influence of hot forming and welding with and without step cooling. Creep data are also reported.

In view of the weight reduction strategies required and increasingly implemented by the automobile industry, growing importance is being attached not only to the materials but also the forming methods used. Forming processes using hydraulic media in particular offer the potential to produce more complex parts economically while optimizing component properties. The tube hydroforming (IHU) and hydromechanical sheet forming (AHU) processes are ideally suited for the production of automotive components in line with these requirements.

An approach is proposed for the evaluation of surface fatiguedamage of hot forming tools that undergo severe thermomechanical loading. Fatigue crack propagation in a hot worktool steel X38CrMoV5-47HRC is investigated using singleedgecracked tension specimens with 3 different thicknesses(2.5, 1, 0.6 mm) and two R-values. The stress intensity factoris evaluated with ABAQUS®. Paris curves are established forthe crack propagation experiments.

Four different techniques have been used to study the thermal cycling effects on equiatomic Ti-Ni: Differential Scanning Calorimetry (DSC), Electrical Resistance measurements (ER), Internal Friction measurements (IF) and Vickers microhardness tests performed at room temperature. The measurements have been performed on well annealed samples, samples cold worked at room temperature and cold worked samples annealed at moderate temperatures.

Good stability of the steel strip is essential in galvanizinglines, especially in the rapid cooling section before the zincbath, where the strip is cooled and excited by high-speedgas jets.
The process parameters and the design have beeninvestigated in order to characterize the strip vibrationsphenomena and to define optimized solutions for improvingthe cooling performances of present and future galvanizinglines while reducing the strip fluttering in the rapid coolingzone as well as in the cooling tower.

The paper introduces a slop detection algorithm, based on imagestaken by a CMOS camera aimed at the converter mouth. Theproposed algorithm, with an accuracy and selectivity of 74%and 94% respectively, is relatively simple and can therefore easilybe used in on-line applications.

Over the past few years several technical efforts have been focused on continuous improvement of quench and tempered product at ArcelorMittal Burns Harbor plate mill facility with particular attention being given to optimization of the flatness of quenched product. Incremental improvement in quench line equipment and practices is being aided by computer-based modelling tools and specialized instrumentation. The paper describes the development of different tools used to control flatness after quench and tempering units. The detailed description of a 3D model designed to predict distortion such as edge waves, center buckles, longbows and crossbows during quenching is presented. The model developed with Abaqus is able to predict the evolution of plate temperature, thermal stresses, strains, and distortions during cooling. The water cooling system is represented by top and bottom movable surfaces where a heat flux depending on width, length and temperature is applied. The effect of phase transformation is approximated by a variation of the plate thermal expansion coefficient.

A micromechanical model based on a new self-consistent formulation has been applied to describe the elastic-viscoplastic behaviour of steels at high strain rates. A good agreement between experimental and calculated data is found concerning the behaviour of a ferritic single-phase IF steel in uniaxial tests in a large range of strain rates. Because of the introduction of relevant physical parameters in the modelling, a good description of the difference observed between the Dual-phase steel and the single-phase steel is obtained.

A physical limit to the galvanizing speed exists over which the liquid film explodes completely and prevents any further wiping. This limit is presently estimated around 180-200 m/min. A dimensionless approach including the Weber and Reynolds numbers is proposed to be able to predict the occurrence of the phenomenon. Practically it comes out that nozzles tilted by 30° down to the pot can pushback the limit by 30 %. A maximal line speed around 220 m/min could thus be reached.

La première étape de ce travail est le calcul ab initio des énergies de mise en solution et de mélange du chrome et du fer. Nous confirmons les résultats ab initio proposés précédemment. Nous utilisons cette même méthodologie afin de calculer les énergies de surface du fer et du chrome dans les orientations (100), (110), (111) et (211). Contrairement aux extrapolations depuis les mesures expérimentales aux hautes températures, ces calculs montrent que les énergies de surface du chrome sont supérieures à celles du fer. Nous calculons également l’énergie de ségrégation d’impureté du chrome dans le fer (100) qui est endothermique. Enfin, nous proposons un modèle énergétique ajusté sur les calculs ab initio. À partir de ce modèle, nous calculons des isothermes de ségrégation et montrons que les surfaces de l’alliage sont toujours appauvries en chrome du fait de la grande différence d’énergie de surface entre les deux éléments qui a été révélée par les calculs ab initio.

Against the background of the several years lasting slump in the real price of stainless steels, different ways to reduce the production costs of these steels are analyzed. They consist in innovative technologies, some of which are already applied and others are still waiting for confirmation at the industrial scale. The emphasis is put on developments made by Voest-Alpine Industrieanlagenbau (VAI).

Several parts of degraded organ pipes belonging to some organs produced in different periods (from the 18th to 20th century) and from different Italian geographical areas have been examined and investigated in order to identify the possible causes of the degradation phenomena. An analysis through DSC-DTA measurements has been performed to define the crystallographic transformation of the studied alloys and a metallographic analysis has been realized to point out the microstructural characteristics. The morphological analysis has been improved by SEM equipped with an EDS device which permits a quantitative chemical characterization of the intact zones and of the degraded ones. The presence of chlorides has been identified as the starting factor of the degradation phenomena.

The fire resistance of structures is one of the main brakes concerning the development of steel in buildings. This handicap of steel is in order to disappear due to the results of recent researches that permit to dimension the steel structures by considering the natural fire and the active fire fighting measures. In the frame of an ECSC financed research, an interactive calculation software has been developed with the aim of enabling engineering offices to perform easily calculations under natural fire conditions. This paper describes this new tool that should contribute to the promotion of steel by making the dimensioning under fire conditions easier and more competitive.

Le comportement atypique des fissures courtes peut être, pour une large part, expliquépar l’effet de la fermeture. Toutefois, la détection du niveau de contrainte correspondantà l’ouverture s’avère généralement difficile sinon impossible pour les fissures de petitedimension. Cette étude porte sur la fermeture des fissures courtes 2D dans un acierinoxydable 304L. Pour optimiser la détection des variations de complaisance, une méthodeautomatique a été développée pour analyser les signaux numériques grâce à des méthodes defiltrage. Il est montré que cet outil permet d’obtenir une mesure précise de la charged’ouverture même pour des fissures ayant une profondeur de l’ordre de 0,1 mm. Lesrésultats obtenus permettent de définir l’évolution de la contribution de la fermeture enfonction de la profondeur de la fissure.