PROCESS FOR THE PRODUCTION OF GRAIN ORIENTED ELECTRICAL STEEL STRIPS

摘要

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 600cm<-1> < Iz <1500 cm<-1> and Iy = 1.9 Fv/r (cm<-1>), Fv being the volume fraction of second phases stable at temperatures of less than 800 DEG 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 DEG 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 DEG 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.