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Centro Sperimentale Metallurgico S.p.a.

Dalmine S.p.a.

Centro Sviluppo Materiali S.p.a.

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

Acciai Speciali S.p.a.

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

Massimo Barteri

Edmondo G Marianeschi

Mario Barisoni

Roberto Ricci Bitti

Pietro Brozzo

Sandro Fortunati

Carlo Borgianni

Antonio Mascanzoni

Sandro C Basevi

Giuseppe Cumino

Gianni Songini

Giorgio Porcu

Roberto Ricci-Bitti

Ivan Nembrini

Carlo Santafe

In the thermal treatment of continuous-cast or hot-rolled steel strip, by using particular solutions regarding the choice of the strip rolling temperatures, the transfer times from the coiler to the furnace, as well as specific process steps in annealing, it is possible to treat any type of steel by sending the coils of strip, still at a high temperature, directly to the annealing furnace, at the same time maintaining the mechanical and microstructural characteristics obtainable in traditional cold-strip annealing.

Process for thermal treatment of steel strip

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&plus;0.5(Nb&plus;Ta)>6C-3S with proviso that Ti>6S, or NB&plus;Ta>1C with the proviso that TI<6S; being in any case Nb&plus;Ti&plus;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&equals;(Creq/Nieq&minus;0.728)&times;500/3 wherein: Creq/Nieq&equals;&lsqb;Cr&plus;Mo&plus;1.5Si&plus;)0.5Nb&plus;0.25Ta&plus;2.5(Al&plus;Ti)&plus;18&rsqb;/&lsqb;Ni&plus;30(C&plus;N)&plus;0.5Mn&plus;36&rsqb;; and, possibly, heating the strip at a temperature between 900 to 1200&deg; C. for a period of time less than 5 minutes. Subject of the invention is also the stainless steel strip obtained with the process and the use thereof for manufactured welded products, i.e. welded tubes.

Austenitic stainless steel strips having good weldability as cast

Martensitic stainless steel having high mechanical strength and

A properly balanced chemical composition and the choice of a heat treatment (annealing and quenching) under controlled conditions allow to obtain uperduplex stainless steel manufactures which, in the hot-worked form, are excellent in resistance to corrosion and have unit tensile yield strength at room temperature of 90 ksi min.

Highly mechanical and corrosion resistant stainless steel and relevant

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.

Process for manufacturing silicon-aluminum steel sheet with oriented

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Rome, Italy

Massimo Barteri