FeCo alloy, FeSi alloy or Fe sheet or strip and production method thereof, magnetic transformer core produced from said sheet or strip, and transformer comprising same

Sheet or strip of cold rolled and annealed ferrous alloy, wherein its composition consists of, in weight percentages:

• 0<C≤0.2%;
• 0<Co≤40%;
• if Co≥35%, 0<Si≤1.0%;
• if 0<Co<35%, 0<Si≤3.5%;
• if 0<Co<35%, Si(wt %)+0.6·Al(wt %)≤4.5(wt %)−0.1·Co(wt %);
• 0<Cr≤10%;
• 0<V+W+Mo+Ni≤4%;
• 0<Mn≤4%;
• 0<Al≤3%;
• 0<S≤0.005%;
• 0<P≤0.007%;
• 0<Ni≤3%;
• 0<Cu≤0.5%;
• 0<Nb≤0.01%;
• 0<Zr≤0.1%;
• 0<Ti≤0.2%;
• 0<N≤0.01%;
• 0<Ca≤0.01%;
• 0<Mg≤0.01%;
• 0<Ta≤0.01%;
• 0<B≤0.005%;
• 0<O≤0.01%;
• the remainder being iron and impurities resulting from the preparation, wherein, for an induction of 1.8 T, the magnetic losses at 400 Hz are of at most 130 W/kg, and the maximum difference (Max Δλ) between the magnetostriction deformation amplitudes λ, measured parallel to the magnetic field (Ha) applied (λ//H) and perpendicular to the magnetic field (Ha) applied (λ⊥H) on three rectangular samples of the said sheet or strip, whose long sides are respectively parallel to the direction of rolling (DL) of the said sheet or strip, parallel to the transverse direction (DT) of the said sheet or strip, and parallel to the direction forming an angle of 45° with the said rolling direction (DL), and with the said transverse direction (DT), is at most 25 ppm, and in that its recrystallization rate is 80 to 100%, and
• wherein each texture component {h0k0l0}<u0v0w0> of the material is not more than 30% by volume of the volumetric fraction of the grains of the material, said texture component being defined by all the grains showing a crystallographic orientation {hkl } [uvw] having an angular disorientation of less than 15° from the specific {h0k0l0}<u0v0w0> orientation that defines said texture component.