Acciai Speciali Terni, S.p.a.

Centro Sviluppo Materiali S.p.a.

Thyssenkrupp Acciai Speciali Terni S.p.a.

Acciali Speciali Terni S.p.a.

Centro Svilippo Materiali S.p.a.

Stefano Cicale'

Stefano Fortunati

Giuseppe Abbruzzese

Claudia Rocchi

A process for the production of a grain oriented magnetic strip, made of steel containing 2.3 to 5.0% of silicon, obtained by producing a hot-rolled sheet containing a distribution of second phases capable of controlling the secondary recrystallization by means of a two-step hot-rolling with an intermediate annealing, and by changing it into the final product.

Process for the production of a grain oriented magnetic strip

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&#x3c;Iz&#x3c;1500 cmand Iy=1.9 Fv/r (cm), Fv being the volume fraction of second phases stable at temperatures of less than 800&#xb0; 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&#xb0; 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&#xb0; 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.

Process for the production of grain oriented electrical steel strips

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.

Process for the production of oriented-grain electrical steel sheet with high magnetic characteristics

The production of grain-oriented electrical steel sheets is disclosed wherein grain growth in the steel is inhibited by a method comprising the regulation of the content of sulfur and manganese in the steel strp and the cold rolled strip is continuously nitrided at high temperature.

Process for the inhibition control in the production of grain-oriented electrical sheets

In the production of high permeability electrical steel, the control of condition of thin slab continuous casting allows to obtain advantageous solidification structures and precipitates. This, in turn, allows to decritize the process for controlling the grain dimensions and to add nitrogen to the cold rolled sheet, such as to immediately form aluminum nitride.

Process for the production of grain oriented electrical steel strip having high magnetic characteristics, starting from thin slabs

In the production of grain oriented electrical steel sheet, controlling the condition of thin slab continuous casting results in advantageous solidification structures and precipitates. The steel has an initial content of carbon less than 300 ppm and an initial content of acid-soluble aluminum higher than that normally used for said type of steel. During the final processing steps, the annealed sheet is nitrided through a limited amount of nitrogen. This, in turn, renders the process for controlling the grain dimensions much less critical and results in a constant quality product.

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Rome, Italy

Stefano Cicale'