Abstract: Environment-friendly process for descaling, pickling and finishing/passivating in a continuous, integrated and flexible manner, applicable to any type of stainless steel, regardless of its physical structure, chemical composition and nature of surface oxides to be removed, within a single plant in which the required chemical, electrochemical, mechanical and hydromechanical treatments are carried out, merely diversifying the operative conditions of each treatment according to the stainless steel type to be processed. The process and the plant according to the invention allow elevated reaction rate, excellent surface quality, low energy and chemical reagent consumption and total environmental compatibility. The figure shows the block diagram of an embodiment of the plant according to the invention.

Abstract: A twin roll caster for an apparatus for confining the impurities in a molten metal fed by means of a discharger and contained into an area of a strip continuous casting mold delimited by the side surfaces of two casting rolls with counter-rotating horizontal axis and by two containment side plates positioned in contact with the rolls' bases is provided.

Abstract: Apparatus for confining the impurities in a molten metal fed by means of a discharger and contained into an area (3) of a strip continuous casting mould delimited by the side surfaces of two casting rolls with counter-rotating horizontal axis (1a, 1b)and by two containment side plates (2a, 2b) positioned in contact with the rolls' bases, comprising: a discharger (4) having at least two first series of holes (4a, 4a?) for the molten metal supply, each series being formed by at least a pair of holes respectively directed towards one of the opposed side surfaces of the two rolls (1a, 1b)and at least a second pair of holes (4b, 4b?) for the molten metal supply, each hole of such second pair being directed towards the side plate nearest thereto, and said at least one second pair of holes (4b, 4b?) being positioned at a greater depth with respect to said two first series of holes (4a, 4a?); at least two pairs of barriers (5) present in one part of the area (3) comprised between the end of the plunger and the co

Abstract: A process for the production of electrical steel strips, in which a strip is directly cast from molten steel and contains alloy elements apt to generate a precipitation of sulphides and/or nitrides apt to inhibit the grain growth. The strip is hot rolled in-line with the casting operation at a temperature between 1250 and 1000° C., and in which the strip is coiled after hot rolling at a temperature of less than 780° C. if sulphides are utilized, or at a temperature of less than 600° C. if nitrides, or nitrides plus sulphides, are utilized.

Abstract: In the production of electrical steel strips, a special islab-reheating treatment before hot rolling is carried out so that the maximum temperature within the furnace is reached by the slab well before its extraction from the furnace. During the heating stage and performance at the highest temperatures of the thermal cycle, second phase particles are dissolved and segregated elements are distributed in the metallic matrix, while during cooling and temperature equalising steps of the slab in the furnace a controlled amount of small second phases particles are more homogeneously re-precipitated from the metallic matrix. Differently from all the conventional processes for the production of electrical steels, the slab reheating furnace become a site in which it is performed the precipitation of a controlled amount of second phases particles for the necessary grain growth control during the successive process steps.

Abstract: A process for the production of grain oriented electrical Fe-Si strips in which a Si-containing alloy is directly cast as a strip between 2.5–5.0 mm thick and cold rolled in one stage, or in more stages with intermediate annealing, to a final thickness of between 0.15–1.0 mm. The strip is then continuously annealed to carry out the primary recrystallization and then annealed to carry out the oriented secondary recrystallization. The process further includes that after solidification of the strip, and before its coiling, a phase transformation from Ferrite to Austenite is induced into the metal matrix for a volume fraction between 25–60%, obtained by controlling the alloy composition so that the Austenite fraction is allowed within the stability equilibrium between the two phases. The strip is then deformed by rolling in-line with the casting step to obtain a deformation higher than 20% in the temperature interval 1000–1300° C.

Abstract: Process for the production of oriented grain electrical steel strips, in which a silicon steel, comprising at least 30 ppm of S, is directly cast as strip 1.5-4.5 mm thick and cold rolled to a final thickness of between 1.0 and 0.15 mm; characterised by the following staged: Cooling and deformation of the solidified strip to obtain a second phases distribution in which 600 cm?1<Iz<1500 cm?1 and Iy=1.9 Fv/r (cm?1), Fv being the volume fraction of second phases stable at temperatures of less than 800° C., and r being the precipitates mean radius, in cm; Hot rolling between solidification and coiling of the strip at a temperature of not less than 750° C., with a reduction ratio of between 15 and 60%; Cold rolling with reduction ratio of 60-92%; Cold rolled strip annealing at 750-1100° C., with increase of the nitrogen content of at least 30 ppm with respect to the initial composition at the strip core, in nitriding atmosphere.

Abstract: It has been found out that in the laser treatment for the control of the magnetic domain sizes in grain oriented electrical silicon steel sheets, by optimizing some essential parameters of the treatment such as specific radiation energy, the distance among the scribed traces, the scanning speed and the dwell time, a contemporaneous improvement of the magnetostriction, induction and core losses can be obtained.

Abstract: In a continuous casting plant for the continuous casting of a thin strip (14), comprising a mold (8) provided with two casting rolls (6, 7), with a strip-like strand (14) being united from two half-shells (12) and exiting in a vertically downward direction at the nip (13) formed by the casting rolls (6, 7) of said mold, a deflecting-supporting means (16) for deflecting the strand (14) emerging vertically from the mold (8) into a roughly horizontal direction is provided below the nip (13). In order to gently transfer the strand (14) from the vertical into the horizontal while avoiding great bending stresses or plastic deformations, the deflecting-supporting means (16) of plate-shaped construction has a surface supporting the strand (14) over a large area (FIG. 1).

Abstract: A process for continuously casting a thin metal strip controls has jets directed at casting rollers using sensor feedback. Sensor feedback can be taken directly from the rollers, or can be determined indirectly by sensing a condition of the thin metal strip. Surface conditions are controlled over a longitudinal extent of the rollers through locally controlled gas jets. The feedback control of the roller surfaces provides a more uniform casting surface and a more consistent output from the casting surface.

Abstract: A process for the production of austenitic stainless steel strips having as case a good weldability, comprising the operations of: solidification in a mold of a continuous casting apparatus with twin counterrotatng rolls, a strip having a thickness comprised between 1 to 5 mm and having the following composition in percent by weight: Cr 17-20; Ni 6-11; c<0.04; n<0.04; s<0.01; Mn<1.5; Si<1.0; Mo 0-3; Al<0.03; and possibly, Ti, Nb, Ta so that: Ti+0.5(Nb+Ta)>6C-3S with proviso that Ti>6S, or NB+Ta>1C with the proviso that TI<6S; being in any case Nb+Ti+Ta<1.0; the remaining part being substantially Fe with a &dgr;-ferrite volume percentage comprised between 4 and 10% calculated with the formula: &dgr;-ferrite=(Creq/Nieq−0.728)×500/3 wherein: Creq/Nieq=[Cr+Mo+1.5Si+)0.5Nb+0.25Ta+2.5(Al+Ti)+18]/[Ni+30(C+N)+0.

Abstract: Process for pickling stainless steel carried out at a temperature of between 20° and 70° C., with the use of a pickling solution containing the following basic ingredients: H2SO4 (free acid): 50 to 200 g/l HF (free acid): 0 to 60 g/l F− anion (total): 5 to 150 g/l SO42− anion (total): 50 to 350 g/l Total free acidity (H2SO4+HF): between 1 and 7 g. equiv./l where by “free acid” is meant the acid that does not constitute the anion bound in the form of salts or complexes with the metal cations present in the solution; and, in addition: Fe3+ in a quantity of at least 15 g/l chloride anion in a quantity of between 0.1 and 10 g/l, into which solution is fed, during the pickling process, an oxidant that is able to oxidize Fe2+ to Fe3+ in order to maintain the redox potential of the solution at a value of between +230 and +800 mV.

Abstract: A refractory plate member (8) for the side containment in continuous casting machines of the type with two counterrotating rollers (1, 2), including two or more overlapped ceramic and/or refractory layers is provided, the plate member (8) is characterized in that the first layer (9, 91) of said plate member (8) is made of a material that is easily wearable under the action of said rolls (1, 2) during the starting step, and in that the second layer (10, 101) underlying the first layer is made of a ceramic and/or refractory and/or carbon material having a very high wear and thermal shock resistance and self-lubricating properties.

Abstract: A process for the production of low carbon steel strips having a good combination of strength an formability, as cast, and a good weldability after the pickling by usual processes, comprising the following steps: casting, in a twin rolls continuous casting machine (1) comprising pinch rolls (3), a strip with a thickness comprised between 1 and 8 mm, having the following composition as weight percentage of the total weight: C 0.02-0.10; Mn 0.1-0.6; Si 0.02-0.35; Al 0.01-0.05; S<0.015; P<0.02; Cr 0.05-0.35; Ni 0.05-0.3; N 0.003-0.012; and, optionally, Ti<0.03; V<0.10; Nb<0.035, the remaining part being substantially Fe; cooling the strip in the area comprised between the casting-rolls and the pinch rolls (3); hot deforming the strip cast through said pinch rolls (3) at a temperature comprised between 1000 and 1300° C. until reaching a thickness reduction less than 15%, in order to encourage the closing of the shrinkage porosites; cooling the strip at a speed comprised between 5 and 80° C.

Abstract: Method for pickling products made of steel, characterized in that within the pickling bath Fe3+ is present, directly added in a controlled concentration, or produced in the pickling bath itself by adding an oxidizing agent such as hydrogen peroxide, ozone, permanganates. persulphates and oxygen.

Abstract: A disadvantage of continuously casting thin metal strips in a continuous casting plant (1) wherein the casting strand (7) exits the mould (2) in a downward direction and is guided in a vertical strand guide (3) with the help of pairs of driver rolls (4, 5) for supporting and conveying the strand (7), is that the force with which the driver rolls (4, 5) are pressed against the strand (7) results in the unchecked rolling of the strand while it is still soft. The aim of the invention is to solve this problem. To that end, the driver rolls (4, 5) are pressed against the strand (7) with a variable pressure (P1, P2) which is regulated “on-line” in accordance with the thickness (d3, d4) of the strand (7), in such a way as to obtain and maintain a constant strand thickness.

Abstract: By forming, after the annealing of the continuously cast body, a limited number of precipitates apt to the control of the grain growth, and utilising a cold rolling reduction ratio of at least 70%, it is possible to obtain in a subsequent step of continuous nitriding the direct formation of nitrides useful for the grain growth control and subsequently, still in a continuous treatment, to at least start the oriented secondary recrystallization.

Abstract: A process for the production of oriented-grain electrical steel sheet with high magnetic characteristics, and more precisely a process in which the slab obtained from continuous casting is continuously nitrided by a reaction between aluminium and nitrogen is described. Amount, size and distribution of precipitates are controlled, enabling a high-temperature continuous heat treatment during which the primary-recrystallization and a high-temperature nitriding are realized.

Abstract: In a method of preventing contact of oxygen with a metal melt, metal melt flows into a casting chamber bounded by walls (1, 2, 13) and leaves this chamber as a stream. In order to completely prevent contact of oxygen with a metal melt and thus reoxidation, oxygen attempting to enter via any gaps (18) between the walls (1, 2, 13) and/or adhering to the walls (1, 2) is reacted to form a compound which is not injurious to the metal melt (20).

Abstract: A cooling roll having superficial dimples, for continuous casting machines with a pair of counterotating rolls in contact with the cast metal is characterized by the fact that it presents the surface that comes to contact with the cast metal provided with a first and a second dimensional order of cavities (6,7) randomly spaced, and optionally, at least partially in contact between them; the strickle impressed on the roll surface (1) of each cavity (6,7) of at least one of said first and second dimensional order being of polygonal or circular shape and, more preferably rhomboidal.