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Centro Sperimentale Metallurgico S.p.a.

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

Pietro Brozzo

Massimo Barteri

Edmondo G Marianeschi

Mario Barisoni

Roberto Ricci Bitti

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.

Process for manufacturing silicon-aluminum steel sheet with oriented

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Albano Laziale (Rome), Italy

Pietro Brozzo