A finite volume computer model of the continuous castingprocess for steel flat products has been developed. In this firststage, the model concentrates on the hydrodynamic aspectsof the process and in particular the dynamic behavior ofthe metal/slag interface. The model was validated againstexperimental measurements obtained in a water model apparatus.

The many heat treatments upon fabrication may deteriorate the tensileproperties of the tempered base material or to alter its weldability ortoughness. It is essential to take into consideration all heat treatmentseach zone is submitted to: base metal, heat affected zone, weld metalin order to optimize the global properties of the vessel. Major issues areillustrated by precise examples. An approach based on the equivalenttempering parameter is put forward.

The targeted carbide-free bainitic TRIP microstructure have been obtained in the studied steels thanks to a specific alloy-design, following a classical hot-rolling schedule followed with a fast cooling regime and a coiling stage. Excellent balance between tensile strength and ductility are achieved and explained by transformation hardening phenomena. The sharp influence of gamma stabilizing elements (copper/nickel/manganese) on phase transformations and mechanical properties is highlighted.

The addition of boron to steel introduces the possibility ofsteel initially completely solidifying and then remelting inthe interdendritic regions at very low carbon levels. For allcarbon levels, a low melting Fe-B alloy exists as a liquiddown to around 1100°C. This liquid is found in steel with aslow as 0.0004% boron due to the boron segregation. Thepersistence of this liquid leads to hot shortness, breakouts,and other casting defects. Pseudo-binary phase diagramsfor low boron concentrations have been developed usingThermoCalc software and were confirmed using experimentaltechniques.

A new automated system installed in the ArcelorMittal Asturiassteel plant in Avilés, based on novel image treatment, aimsat performing an on-line inspection, with feed-back to theprocess, verifying the effectiveness of scarfing. It detectsremaining defects as well as new ones introduced by thisoperation, thus allowing a quick and reliable assessment offinal surface quality.

Asymmetric hot rolling has been found to decrease therolling loads, to increase recrystallisation kinetics and torefine the grain size. Thereby this rolling practice opensthe way to save energy, to decrease hot band thickness,to enlarge formats, to increase strength, to reduce alloyingadditions and to improve formability.

The new standard EN 14140:2004 permits the use of HighStrength Steel grades for the manufacturing of cylinders havinga steel sheet thickness lower than the limit imposed by theolder EN 1442:1998. The new steel grades proposed for themanufacturing of light weight LPG cylinders have been thoroughlycharacterized in terms of their in-process behavior.

The relationship between water quality management andthe total cost of operation of the steel mill are normallyunderestimated as areas of relevant cost reduction andproductivity improvements.The work that was accomplished on cooling water systemsassociated with n°4 slab caster at CSN from 2004 toincrease significantly steel plant productivity and reduce thetotal cost of operation is reported.

CVC plus® is a worldwide established and well proventechnology package to control profile and flatness in hot stripmills and plate mills. Latest developments of this technologyare the application of CVC plus® grindings on work and backuprolls, CVC plus® grindings of higher order and intelligentshifting strategies. The capability of the developments isdemonstrated with recent operational results.

An integrated model developed by ArcelorMittal andNSC to predict the microstructural evolution of austenite inconventional and microalloyed HSLA steels during multi-passhot rolling is described. The prediction of austenite grain size,recrystallized fraction, residual strain and precipitation stateare given. Applications of this model during mono-deformationtests and during multi-pass rolling are presented.

Thin organic coated steels have been widely used in thebuilding industry due to their formability, anticorrosive and antifingerprint characteristics. In this work paintability propertiesof these coated steels were studied. Several thin organic coatedsteel sheets were treated by means of a roll coater followingstandard procedures (primer + topcoat) and only with topcoat(in this case, the thin organic coating was used as a primer).Characterization tests were carried out in terms of gloss,hardness, adherence and corrosion resistance.

Nakayama Steel Works LTD. has succeeded in attainingthe cooling rate (105 -106 K/s) necessary for amorphouslayering technique by using the innovative idea ofimmediately cooling the spraying flame. Amorphous alloy(Fe70Cr10P13C7) formed by the new technique displays acorrosion resistance more than 500 times higher than the oneof SUS316L in aqua-regia immersion test, while the similarlyformed amorphous magnetic alloy film (Fe81B13Si4C2)indicates high magnetism of 15.4 kGauss in magnetic fluxdensity.

The effect of the so-called “warm” or “ferritic” rolling on themicrostructure and recrystallization behavior of LC steelsduring continuous annealing is reported. The followingparameters were investigated; reduction rate in ferriterolling, coiling temperature; soaking annealing temperature,overageing temperature. Thin gages low carbon steelssuitable for replacing conventional cold rolled and annealedsteel sheet can be produced.

A review of the degassing process, including basicprinciples, is done followed by the assessment of castabilityissues. Steelmaking practices that could lead to potentialplugging in the submerged entry nozzles at the casters areoutlined. The steel cleanliness is discussed for a select steelgrade including a brief review of inclusion characterization.

With extremely high cooling rates, a combined laminar jet andspray nozzle design cooling facility is the most advanced tool forthe evolution of mechanical properties of high-strength steels. Themain metallurgical aspects of Accelerated Cooling (ACC) andDirect Quenching (DQ) are presented. Typical plate applicationsare brought up. Design, engineering and operational aspects ofmodern cooling facilities are explained. Of particular importancefor a homogenous cooling process is a powerful process controlfeaturing advanced process models.

Very little light gauge steel framing is used for dwellings in Europe.The main reasons are the lack of standards, common proceduresand the difficulties to design such structures with Eurocode 3 part1-3. ArcelorMittal has supported the development of a designtool for low-rise steel framed buildings. The objective is to increasethe light steel framing market thanks to a comprehensive and userfriendly design package. The tool is based on a clearly definedscope and includes conception rules, design method by graphs anda construction details library.

Duplex stainless steels present simultaneously very diversified technicalchallenges and very attractive in service properties along withexcellent cost/properties ratios particularly in very critical markets: oiland gas, chemical industry, pulp and paper industry, water systems,desalination plants, pollution control equipments, chemical tankers.This paper reviews the 100 scientific contributions at the latestinternational Duplex Stainless Steel Conference DSS'07 in Grado,Italy, June 18-20, 2007.

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.

The phase-field method has emerged as a method ofchoice for the description of microstructure evolutionand phase transitions in metallic materials. Following ageneral thermodynamic extremal principle a set of evolutionequations for the structural variables of the system, the socalled phase-fields, are derived. The paper reviews shortlythe historical and theoretical background of the multi-phasefieldmethod that is an extension of the classical phase-fieldmethod to multi-phase multi-component materials. Examplesare given from solidification, solid state transformations andgrain growth.

Stainless steel reinforcement extends the life of concrete, at higherinitial costs that may be compensated for by the reduction ofmaintenance. The effect of several parameters on the galvaniccoupling between carbon and stainless steel is reported. It isdemonstrated that the introduction of stainless steel rebars do notaccelerate the intrinsic corrosion of carbon steel, depending oncommon rules about surface ratio and number of contact points.