METHOD OF PRODUCING GRAIN ORIENTED ELECTRICAL STEEL SHEET

摘要

Provides is a method of producing a grain oriented electrical steel sheet by heating a steel slab having a predetermined composition, then subjecting the slab to hot rolling to obtain a hot rolled sheet, then optionally subjecting the hot rolled sheet to hot band annealing and subsequent cold rolling once, or twice or more with intermediate annealing performed therebetween to obtain a cold rolled sheet with final sheet thickness, then subjecting the cold rolled sheet to primary recrystallization annealing and subsequent secondary recrystallization annealing, in which the aging index AI of the steel sheet before final cold rolling is set to 70 MPa or less to effectively grow Goss-oriented grains to thereby obtain a grain-oriented electrical steel sheet with good magnetic properties, without the restriction of containing a relatively large amount of C.

主权项

1. A method of producing a grain oriented electrical steel sheet, the method comprising:
heating a steel slab having a composition containing by mass %
C: 0.0005% to 0.005%,Si: 2.0% to 4.5%,Mn: 0.005% to 0.3%,S and/or Se (in total): 0.05% or less,sol.Al: 0.010% to 0.04%,N: 0.005% or less, andthe balance being Fe and incidental impurities; then subjecting the slab to hot rolling to obtain a hot rolled sheet; then optionally subjecting the hot rolled sheet to hot band annealing; then subjecting the hot rolled sheet to cold rolling once, or twice or more with intermediate annealing performed therebetween to obtain a cold rolled sheet with final sheet thickness; and then subjecting the cold rolled sheet to primary recrystallization annealing; then subjecting the cold rolled sheet to secondary recrystallization annealing, wherein a solute C content parameter X calculated from the following formula (1) is used, and an average cooling rate R (° C./s) between 800° C. and 200° C. after a heating process right before final cold rolling is set to or lower than an upper limit average cooling rate RH calculated from the following formula (2) to achieve an aging index AI of the steel sheet before the final cold rolling of 70 MPa or less,
X=[% Si]/28.09+100[% C]/12.01  (1)RH=10/X  (2) where [% M] in formula (1) represents the content of element M (mass %).