A grain-oriented electrical steel sheet has a steel sheet and an insulating coating which is formed on a surface of the steel sheet. In the insulating coating, a metal phosphate and a colloidal silica are contained, the colloidal silica is contained in an amount of 20 to 150 parts by mass with respect to 100 parts by mass of the metal phosphate, one or more kinds of fine particles selected from the group consisting of silicon carbide, silicon nitride, aluminum nitride, boron nitride, sialon, and cordierite are further contained in an amount of 0.5 to 7 parts by mass with respect to 100 parts by mass of the metal phosphate, an average particle size of the fine particles is 0.3 to 7.0 μm, crystallized ratio of the metal phosphate is 2% to 40%, and chromium is not contained.

A grain-oriented electrical steel sheet has a steel sheet and an insulating coating which is formed on a surface of the steel sheet. In the insulating coating, a metal phosphate and a colloidal silica are contained, the colloidal silica is contained in an amount of 20 to 150 parts by mass with respect to 100 parts by mass of the metal phosphate, one or more kinds of fine particles selected from the group consisting of silicon carbide, silicon nitride, aluminum nitride, boron nitride, sialon, and cordierite are further contained in an amount of 0.5 to 7 parts by mass with respect to 100 parts by mass of the metal phosphate, an average particle size of the fine particles is 0.3 to 7.0 μm, crystallized ratio of the metal phosphate is 2% to 40%, and chromium is not contained.

A non-oriented electrical steel sheet with an average magnetostriction λ.sub.p-p at 400 Hz and 1.0 T of not more than 4.5×10.sup.−6, and area ratio of recrystallized grains at a section in rolling direction of steel sheet of 40 to 95% and an average grain size of 10 to 40 μm is obtained by subjecting a steel slab containing, in mass %, C: not more than 0.005%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005% and Nb: not more than 0.005% and satisfying Si—2Al—Mn≥0 to hot rolling, hot-band annealing, cold rolling and finish annealing under adequate cold rolling and finish annealing conditions, and a motor core is manufactured by such a steel sheet.

An annealing separator for an oriented electrical steel sheet includes: a first component including a Mg oxide or a Mg hydroxide; and a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof.

An annealing separator for an oriented electrical steel sheet includes: a first component including a Mg oxide or a Mg hydroxide; and a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof.

Grain-oriented electrical steel sheet excellent in magnetic properties and excellent in adhesion of a primary coating to the steel sheet is provided. The grain-oriented electrical steel sheet is provided with a base steel sheet having a chemical composition containing C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.050 to 1.000%, a total of S and Se: 0.005% or less, sol. Al: 0.005% or less, and N: 0.005% or less and having a balance of Fe and impurities and a primary coating having Mg.sub.2 SiO.sub.4 as a main constituent formed on a surface of the base steel sheet. A peak position of Al emission intensity obtained when conducting elemental analysis by glow discharge spectrometry from a surface of the primary coating in a thickness direction is present in a range of 2.0 to 12.0 μm from a surface of the primary coating to the thickness direction. A sum of perimeters of the Al oxides at the peak position of Al emission intensity is 0.20 to 1.00 μm/μm.sup.2, and a number density of Al oxides is 0.02 to 0.20/μm.sup.2.

Grain-oriented electrical steel sheet excellent in magnetic properties and excellent in adhesion of a primary coating to the steel sheet is provided. The grain-oriented electrical steel sheet is provided with a base steel sheet having a chemical composition containing C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.050 to 1.000%, a total of S and Se: 0.005% or less, sol. Al: 0.005% or less, and N: 0.005% or less and having a balance of Fe and impurities and a primary coating having Mg.sub.2 SiO.sub.4 as a main constituent formed on a surface of the base steel sheet. A peak position of Al emission intensity obtained when conducting elemental analysis by glow discharge spectrometry from a surface of the primary coating in a thickness direction is present in a range of 2.0 to 12.0 μm from a surface of the primary coating to the thickness direction. A sum of perimeters of the Al oxides at the peak position of Al emission intensity is 0.20 to 1.00 μm/μm.sup.2, and a number density of Al oxides is 0.02 to 0.20/μm.sup.2.

A method for manufacturing a hot-dip galvanized steel sheet according to one aspect of the present invention includes an annealing step of reduction-annealing a steel sheet having a Si content of 1.0% by mass or more and 3.0% by mass or less at a temperature equal to or higher than an A3 point of the steel sheet in an atmosphere having a dew point of −20° C. or higher; and a hot-dip galvanizing step of making the annealed steel sheet enter into a galvanizing bath to form a galvanized layer on a surface of the steel sheet, wherein a temperature of the steel sheet entering into the galvanizing bath is set to 390° C. or lower.

An annealing separator for an oriented electrical steel sheet including: a first component includes a Mg oxide or a Mg hydroxide; and a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof.

An annealing separator for an oriented electrical steel sheet including: a first component includes a Mg oxide or a Mg hydroxide; and a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof.