Centro Sperimentale Metallurgico S.p.a.

Terni Societa Per L'industria E L'elettricita S.p.a.

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Terni Societa Per 1'industria E'elettricita S.p.a.

Terni-societe Per 1'industria E L'elettricita S.p.a.

Edmondo G Marianeschi

Mario Barisoni

Massimo Barteri

Roberto Ricci Bitti

Paolo Marini

Carlo Borgianni

Sandro C Basevi

Pietro Brozzo

Carlo Santafe

Gennaro Versaci

Roberto Ricci-Bitti

A coating solution for forming on electrical steel strips an electrical insulation coating for tensioning the strip, contains on a dry weight basis for every 100 parts by weight of phosphoric acid, calculated as P.sub.2 O.sub.5, from 10 to 35 parts by weight of Ca.sup.2+ ions, calculated as CaO, from 70 to 200 parts by dry weight of colloidal SiO.sub.2, and from 40 to 200 parts by weight of water for every 100 parts of P.sub.2 O.sub.5. The solution may also contain up to 20 parts by weight of Mg.sup.2+ calculated as MgO, up to 30 parts by weight of Cr.sup.6+ calculated as CrO.sub.3, and/or up to 30 extra parts by weight of phosphoric acid calculated as P.sub.2 O.sub.5. The density of the solution is from 1.25 to 1.35 g/cc, and the value of the molar ratio R=(CaO+MgO)/(P.sub.2 O.sub.5 +CrO.sub.3) is from 0.7 to 0.9.

Coating solution for applying tensioning coatings to electrical steel

Molten metal is fed to an ingot during solidification, in order to compensate for shrinkage and segregation, by electroslag remelting (ESR). The electrodes are positioned entirely in the slag and comprise an inner electrode surrounded by an outer electrode, so that current flow is substantially horizontal through the slag. Powdered solid slag can be filled in the space between the electrodes before ESR begins; and for this purpose, the lower end of the outer or surrounding electrode is temporarily closed by a metal sheet which melts when the current is turned on, thereby to release molten slag onto the bath at the top of the ingot. The electrode arrangement is useful both with consumable and with nonconsumable electrodes.

Method and apparatus for feeding molten metal to an ingot during

An annealing separator for use on grain-oriented silicon steel strip comprises a magnesium oxide base composition containing rare earth metal oxides. The rare earth metal oxides are present in an amount of 0.8 to 30% by weight of the composition; but in the lower range of 0.8 to 5% by weight, and preferably up to 7% by weight, the oxides have a particle size of less than 325 mesh, and a fraction of 35-55% by weight smaller than 500 mesh. Alkali metal silicate may be present in an amount 5 to 45% by weight. Strip coated with annealing separator of the invention is characterized in that the coating is almost totally free of surface cavities, in that the denitriding and desulfuring rates are greatly accelerated, in that the surface resistivity of the coating is substantially increased, and in that the coating adheres more strongly to the strip.

Annealing separator and steel sheet coated with same

A process for inhibiting grain growth in the production of a single oriented continuously cast silicon steel strip with high magnetic characteristics, including the steps of continuously casting a silicon steel strip; solubilizing iron sulfide in the silicon steel strip by uniformly heating the strip to a temperature between 1050.degree. and 1250.degree. C; slowly cooling the silicon steel strip to a temperature below 500.degree. C to precipitate dissolved sulfur as manganese sulfide; and hot-rolling the continuously cast silicon steel strip at a temperature over 1300.degree. C.

Process for the production of a silicon steel strip with high magnetic

A process for the production of oriented-grain high magnetic permeability steel sheet including the steps of continuously casting a steel slab haing a weight % composition within the range of 2.5-3.5 Si, 0.01-0.04 S, less than 0.07 C, less than 0.15 Mn, and an acid-soluble aluminum in an amount between 0.01 and 0.05, at a feed rate ranging from 700 to 1000 kg/minute, into an ingot mold of a length over 1200 mm and cooling it in said ingot mold with a quantity of water ranging from 2.8 to 4 m.sup.3 per ton of steel; heating the slab so obtained to 1300.degree.-1400.degree. C and immediately thereafter hot-rolling it to a thickness in the range between 2 and 3.1 mm, annealing the strip so obtained at a temperature in the range between 1050.degree. and 1150.degree. C, keeping it at this temperature for a duration between 5 and 30 seconds; cooling it at any desired cooling rate to 750.degree.-850.degree. C at a temperature at which austenite is still present in it; keeping the strip at this temperature for a duration ranging from 30 to 200 seconds; and finally quenching it from the initial quenching temperature of 400.degree. C at a cooling rate of between 10.degree. C/second and 100.degree. C/second; cold-rolling the strip so obtained with a reduction rate ranging from 80 to 90% and subjecting it finally to the decarburization and recrystallization annealing operations as well as to other final anneals.

Method for the production of high-permeability magnetic steel

Low carbon silicon-aluminum single-oriented steel sheet having high magnetic induction is produced by hot rolling at 1370.degree.-1430.degree.C., annealing from 10 to 60 seconds at 1050 to 1170.degree.C., slow cooling to 700.degree.-900.degree.C., quenching from 700.degree.-900.degree.C., cold rolling with a reduction in thickness of 80 to 90%, recrystallization and decarburization annealing in wet hydrogen from 780.degree. to 870.degree.C. for 2 minutes, and final annealing at 1200.degree.C. in a mixture of 10-50% hydrogen and 50-90% nitrogen. Cold rolling can be effected in two stages, the first stage to reduce the thickness by 20 to 50% followed by annealing at 700.degree. to 900.degree.C., quenching and final cold rolling with a reduction in thickness of 80 to 90%. The preferred temperature range prior to quenching, for one-step cold rolling, is 750.degree. to 850.degree.C.; and for two-step cold rolling, the first quench is preferably from a temperature of 750.degree. to 850.degree. C. and the second quench preferably from a temperature of 850.degree. to 900.degree.C.

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Terni, Italy

Edmondo G Marianeschi