Cold-rolled steel strip with silicon content of at least 3.2 wt and used for electromagnetic purposes

摘要

The present invention relates to a cold-rolled steel strip or sheet in thicknesses of ≦0.70 mm for electromagnetic applications, consisting of a steel containing (in % by weight) C: 0.01%, Si: 3.2-7%, Al: 2%, Mn: ≦1%, the remainder being iron and usual impurities, which after smelting has been cast to form a base material, such as a slab, a thin slab, or a thin strip, which has then been heated through to temperature T_R1000° C. and has been final hot-rolled at a hot-rolling final temperature T_F800° C. to form a hot strip, which has then been cooled, starting from a temperature T_C of the hot strip amounting to at least 750° C. but less than 850° C., at a cooling speed ΔT/Δt of at least 400° C./min. to a temperature of less than 300° C., subjected after cooling to a surface treatment such as mechanical descaling and/or pickling, after the surface treatment has been cold-rolled at a temperature amounting to maximum 500° C., and has finally been final-annealed.