Patent ID: 9328396
Filing Date: 2016-05-03
CPC Classification: B21B,C21D,C22C,H01F

Claim Text:
1. A process for the production of oriented grain magnetic strip, wherein a steel slab consisting of, in weight percentage, C 0.010-0.100%, Si 2.0-4.5%, Al 0.005-0.050%, N plus S<0.030%, and as a first optional component Se may be present such that S plus (32/79) Se is in the range of 0.005-0.025%, and as a second optional component at least an element selected from Al, Ti, V, Nb, Zr, B, W may be present for a total weight percentage not higher than 0.035%, and as a third optional component at least one of the elements in the series Mn, Cu for a total weight percentage not higher than 0.300% may be present and as a fourth optional component at least one of the elements in the series of Sn, As, Sb, P, Bi for a total weight percentage not higher than 0.150%, may be present the remainder being iron apart from impurities, undergoes, after casting and solidification, a thermo-mechanical cycle comprising the following operations: a) heating at a temperature value in the range of 1100-1300° C.; b) hot roughcast rolling, in a first roughcast rolling mill, in at least two subsequent rolling steps, until the obtaining of a bar having a thickness not higher than 40 mm, with a reduction rate of the total thickness higher than 75% and with a rolling temperature higher than 950° C., c) transfer of the so produced bar from the first roughcast rolling mill to a second finishing rolling mill in a time in the range of 5 to 60 s, d) hot finishing rolling, in a second finishing rolling mill, in at least two steps of subsequent rolling, the first rolling step with a thickness reduction higher than 40% and temperatures in the range of 900° C. to 1100° C., and the second and last rolling step with a thickness reduction rate lower than 25% and temperatures not higher than 850° C., e) being the hot rolled sheet subjected, during said hot finishing rolling, between the first step and at least one of the subsequent step of rolling, to at least a thermal treatment in the temperature range of 800° C. to 1100° C. and in the time range comprised between 10 and 900 s wherein wherein the hot rolled sheet undergoes a thermal treatment in the temperature range of 800-1000° C. for a whole permanence minimum time set according to the following scheme: t minimum=10 s for heating temperature 1050° C.<T<1100° C. t minimum=20 s for heating temperature 1000° C.<T<1050° C. t minimum=60 s for heating temperature 950° C.<T<1000° C. t minimum=100 s for heating temperature 900° C.<T<950° C. t minimum=300 s for heating temperature 800° C.<T<900° C.