Production manner null of the directivity silicon steel sheet which is not the iron loss degradation with the strain taking annealing and is superior in coat

摘要

PURPOSE: To secure the superior characteristics of a film forming on the surface of a steel sheet and further to prevent iron loss deterioration due to stress relief annealing in the case of producing a grain-oriented silicon steel sheet. ;CONSTITUTION: In the case of applying a separation agent at annealing composed essentially of MgO to the surface of a silicon steel sheet after decarburizing annealing and then subjecting the steel sheet to secondary recrystallization annealing and to purification annealing, Ti oxide or Ti compound forming into Ti oxide by heating is incorporated into the separation agent at annealing by 1.0-40 pts.wt. expressed in terms of TiO₂. for 100 pts.wt. MgO and purification annealing is done at 1150-1250°C in a nonoxidizing atmosphere of ≥10vol.% nitrogen concentration from the beginning to at least the time (t (min)) given by the undermentioned equation and then in a hydrogen atmosphere of 3vol.% nitrogen atmosphere: t(min)=668-19.1x+0.171x²-4.42×10^-4x³, where (x) means nitrogen concentration (vol.%) in the atmosphere.;COPYRIGHT: (C)1993,JPO&Japio