A grain-oriented electrical steel plate of an exemplary embodiment of the present invention has a groove formed on a surface, wherein a curvature radius RBb at a position where a depth of the groove is maximum is 0.2 μm to 100 μm, and a curvature radius RSb on the groove surface from the position where the depth of the groove is maximum to a quarter-way position of the depth D of the groove is 4 μm to 130 μm.

Provided is a method for manufacturing a steel sheet, the method including: reheating a steel slab at a temperature of 1200° C. to 1350° C., the steel slab including, by weight%, carbon (C): 0.05% to 0.14%, silicon (Si): 0.01% to 1.0%, manganese (Mn): 1.5% to 2.5%, aluminum (Al): 0.01% to 0.1%, chromium (Cr): 0.005% to 1.0%, phosphorus (P): 0.001% to 0.05%, sulfur (S): 0.001% to 0.01%, nitrogen (N): 0.001% to 0.01%, niobium (Nb): 0.005% to 0.06%, titanium (Ti): 0.005% to 0.11%, and a balance of iron (Fe) and inevitable impurities; finish hot rolling the reheated steel slab under predetermined conditions to obtain a hot-rolled steel sheet; cooling the hot-rolled steel sheet at a cooling rate of 10° C./s to 100° C./s to a temperature of 400° C. to 500° C. after the finish hot rolling; and coiling the steel sheet at a temperature of 400° C. to 500° C. after the cooling.

The present invention is directed at a method of production gain oriented Fe—Si steel sheet presenting an induction value at 800 A/m above 1.870 Tesla and a core power loss lower than 1.3 W/kg at a specific magnetic induction of 1.7 Tesla (T). The steel chemical composition comprises, in weight percentage: 2.8≦Si≦4, 0.20≦Cu≦0.6, 0.05≦Mn≦0.4, 0.001≦Al≦0.04, 0.025≦C≦0.05, 0.005≦N≦0.02, 0.005≦Sn≦0.03, S≦0.015 and optionally Ti, Nb, V or B in a cumulated amount below 0.02, the following relationships being respected: Mn/Sn≦40, 2.0≦C/N≦5.0, Al/N≦1.20, and the balance being Fe and other inevitable impurities.

Provided is a linear groove formation pattern with which both an effect of reducing the building factor and a high magnetic flux density can be obtained. In a grain-oriented electrical steel sheet having a plurality of linear grooves extending in a direction crossing a rolling direction of the steel sheet on a surface of the steel sheet, a surface of the steel sheet between the linear grooves has a recessed defect that is recessed from the surface, a volume fraction of the recessed defect in the steel sheet is 0.0025 vol % or more and 0.01 vol % or less of a steel sheet without the recessed defect, and discontinuous portions that disrupt the extension of the linear grooves are provided at a frequency of 30 or more and 200 or less per square meter of the steel sheet.

This grain-oriented electrical steel sheet is a grain-oriented electrical steel sheet including a base steel sheet and a tension coating, in which, when an average coating thickness of a flat surface coating portion is referred to as t1 (μm), a minimum coating thickness of a groove forming surface coating portion is referred to as t2.sub.Min (μm), and a maximum coating thickness of the groove forming surface coating portion is referred to as t2.sub.Max (μm), Expressions (1) and (2) are satisfied, and when a value of 0.95 times a distance D of the tension coating along a sheet thickness direction from a bottom surface position of the groove forming surface coating portion to a bottom surface position of the flat surface coating portion is referred to as an effective depth d (μm), Expression (3) is satisfied.

t2.sub.Min/t1≥0.4  (1)

t2.sub.Max/t1≤3.0  (2)

t2.sub.Max≤d/2  (3)

An oriented electrical steel sheet includes Ba at about 0.005 wt % to about 0.5 wt % inclusive, Y at about 0.005 wt % to about 0.5 wt % inclusive, or a composite of Ba and Y at about 0.005 wt % to about 0.5 wt % inclusive, the remainder including Fe and impurities, based on 100 wt % of a total composition of a base steel sheet thereof.

Provided are high-strength steel having superior brittle crack arrestability and a production method therefor. The high-strength steel comprises 0.05-0.1 wt % of C, 0.9-1.5 wt % of Mn, 0.8-1.5 wt % of Ni, 0.005-0.1 wt % of Nb, 0.005-0.1 wt % of Ti, 0.1-0.6 wt % of Cu, 0.1-0.4 wt % of Si, at most 100 ppm of P, and at most 40 ppm of S with the remainder being Fe and other inevitable impurities, and has microstructures including one structure selected from the group consisting of a single-phase structure of ferrite, a single-phase structure of bainite, a complex-phase structure of ferrite and bainite, a complex-phase structure of ferrite and pearlite, and a complex-phase structure of ferrite, bainite, and pearlite. The high-strength steel has high yield strength and superior brittle crack arrestability.

The invention concerns a method for accentuating the orientation of the grains of a continuous steel sheet (1), in particular for producing electrical sheet steel, said method involving, during the movement of the steel sheet (1) in the longitudinal direction of same, a longitudinal stretching of the steel sheet (1) in a stretch region (1d) in which the steel sheet (1) moves at a temperature of between approximately 750° C. and approximately 900° C. The invention also concerns a device for implementing said method in which the stretching is carried out by two tensioning blocks (41, 42) comprising traction rollers arranged to move and guide the steel sheet (1). The invention further concerns a facility for producing electrical sheet steel comprising a line comprising a rolling mill and on which said method and said device are implemented downstream from the rolling mill.

A steel sheet for cans has a chemical composition containing, by mass %, C: 0.015% or more and 0.150% or less, Si: 0.04% or less, Mn: 1.0% or more and 2.0% or less, P: 0.025% or less, S: 0.015% or less, Al: 0.01% or more and 0.10% or less, N: 0.0005% or more and less than 0.0050%, Ti: 0.003% or more and 0.015% or less, B: 0.0010% or more and 0.0040% or less, and the balance being Fe and inevitable impurities. The steel sheet has a microstructure including a ferrite phase as a main phase and at least one of a martensite phase and a retained austenite phase as a second phase, the total area fraction of the second phase being 1.0% or more, and the sheet has a tensile strength of 480 MPa or more, a total elongation of 12% or more, and a yield elongation of 2.0% or less.

Provided is a high-strength hot-rolled steel sheet containing, by mass %, C: 0.050 to 0.200%, Si: 0.01 to 1.5%, Mn: 1.0 to 3.0%, B: 0.0002 to 0.0030%, Ti: 0.03 to 0.20%, P: limited to 0.05% or less, S: limited to 0.005% or less, Al: limited to 0.5% or less, N: limited to 0.009% or less, and one or more of Nb: 0.01 to 0.20%, V: 0.01 to 0.20%, and Mo: 0.01 to 0.20%, with the balance being composed of Fe and inevitable impurities. In the high-strength hot-rolled steel sheet, a ratio of a length of small-angle crystal grain boundaries that are boundaries having a crystal orientation angle of 5° or more but less than 15° to a length of large-angle crystal grain boundaries that are boundaries having a crystal orientation angle of 15° or more is 1:1 to 1:4, an total segregation amount of C and B in the large-angle grain boundaries is 4 to 20 atoms/nm.sup.2, tensile strength is 850 MPa or higher, and a hole expansion ratio is 25% or more.