Disclosed are an oriented electrical steel sheet and a manufacturing method thereof. An exemplary embodiment of the present invention provides a method of manufacturing an oriented electrical steel sheet, including: providing a slab including Si at 1.0 to 4.0 wt %, C at 0.1 to 0.4 wt %, and the remaining portion including Fe and other inevitably incorporated impurities; reheating the slab; producing a hot rolled steel sheet by hot rolling the slab; performing annealing of the hot rolled steel sheet; cold rolling the annealed hot rolled steel sheet; decarburizing and annealing the cold rolled steel sheet; cold rolling the decarburized and annealed steel sheet; and final annealing the cold rolled steel sheet.

Disclosed are an oriented electrical steel sheet and a manufacturing method thereof. An exemplary embodiment of the present invention provides a method of manufacturing an oriented electrical steel sheet, including: providing a slab including Si at 1.0 to 4.0 wt %, C at 0.1 to 0.4 wt %, and the remaining portion including Fe and other inevitably incorporated impurities; reheating the slab; producing a hot rolled steel sheet by hot rolling the slab; performing annealing of the hot rolled steel sheet; cold rolling the annealed hot rolled steel sheet; decarburizing and annealing the cold rolled steel sheet; cold rolling the decarburized and annealed steel sheet; and final annealing the cold rolled steel sheet.

A cold-rolled sheet is provided. The cold-rolled sheet includes a steel substrate with a carbon content C.sub.0 between 0.07% and 0.5%, expressed by weight, and a metal pre-coating on at least the two principal faces of the steel substrate. The substrate has a decarburized area on the surface of each of the two principal faces. The depth p.sub.50% of the decarburized area is between 6 and 30 micrometers, and p.sub.50% is the depth at which the carbon content is equal to 50% of the content C.sub.0. The sheet does not contain a layer of iron oxide between the substrate and the metal pre-coating.

When a steel material is processed to produce a grain-oriented electrical steel sheet, conditions of a decarburization annealing process and conditions of a process before the decarburization annealing are adjusted so that a difference in concentration of O, Si, Al, Mn and P between the front and back surfaces of the steel sheet after the decarburization annealing is within a given range with respect to an average concentration between the front and back surfaces, and hence the difference in concentration of each of O, Si and Mg between the front and back surfaces of the product sheet is within ±5%, the difference in concentration of one or more of Al, Mn and P between the front and back surfaces is within ±15% and the difference in the concentration of one or more of Ca and Ti between the front and back surfaces is within ±20%.

This grain-oriented electrical steel sheet includes a base steel sheet, a forsterite-based primary film disposed on a surface of the base steel sheet, and a phosphate-based tension-imparting film containing no chromium, which is disposed on a surface of the primary film. In a case where a Ti content and a S content are respectively expressed as XTi and XS, by mass %, the forsterite-based primary film satisfies Expression (1) and Expression (2). A strain-introduced magnetic domain control is performed on the grain-oriented electrical steel sheet.

0.10≤XTi/XS≤10.00   Expression (1)

XTi+XS≥0.10 mass %.   Expression (2)

This grain-oriented electrical steel sheet includes a base steel sheet, a forsterite-based primary film disposed on a surface of the base steel sheet, and a phosphate-based tension-imparting film containing no chromium, which is disposed on a surface of the primary film. In a case where a Ti content and a S content are respectively expressed as XTi and XS, by mass %, the forsterite-based primary film satisfies Expression (1) and Expression (2). A strain-introduced magnetic domain control is performed on the grain-oriented electrical steel sheet.

0.10≤XTi/XS≤10.00   Expression (1)

XTi+XS≥0.10 mass %.   Expression (2)

A joint structure, includes: a first member including a high tensile strength steel; a second member including a high tensile strength steel and superposed on the first member; a surface soft layer formed on at least one of a superposition surface of the first member, on which the second member is superposed, and a superposition surface of the second member, on which the first member is superposed; a molten-solidified portion formed by melting and solidifying the first member and the second member; and a heat affected zone formed around the molten-solidified portion, in which the surface soft layer has a total thickness of 5 μm to 200 μm, and the molten-solidified portion has a carbon amount of 0.21 mass % or more, and a maximum Vickers hardness of the surface soft layer in the heat affected zone is 100 Hv to 500 Hv.

A joint structure, includes: a first member including a high tensile strength steel; a second member including a high tensile strength steel and superposed on the first member; a surface soft layer formed on at least one of a superposition surface of the first member, on which the second member is superposed, and a superposition surface of the second member, on which the first member is superposed; a molten-solidified portion formed by melting and solidifying the first member and the second member; and a heat affected zone formed around the molten-solidified portion, in which the surface soft layer has a total thickness of 5 μm to 200 μm, and the molten-solidified portion has a carbon amount of 0.21 mass % or more, and a maximum Vickers hardness of the surface soft layer in the heat affected zone is 100 Hv to 500 Hv.

Coated grain oriented electrical steel plates and methods of producing the same are provided. In an exemplary embodiment, a method includes producing molten steel with from about 2.5 to about 4 weight percent silicon, from about 0.005 to about 0.1 weight percent carbon, and from about 90 to about 97.5 weight percent iron. The molten steel is cast into a slab and then cold rolled into a plate having a surface. The plate is decarbonized using a decarbonization anneal, and then recrystallized using a recrystallization anneal to produce grain oriented electrical steel. A coating is applied overlying the surface, where the coating includes an organic radiation curable crosslinking agent and a photo-initiator. The coating is cured by exposing it to a radiation source.

Coated grain oriented electrical steel plates and methods of producing the same are provided. In an exemplary embodiment, a method includes producing molten steel with from about 2.5 to about 4 weight percent silicon, from about 0.005 to about 0.1 weight percent carbon, and from about 90 to about 97.5 weight percent iron. The molten steel is cast into a slab and then cold rolled into a plate having a surface. The plate is decarbonized using a decarbonization anneal, and then recrystallized using a recrystallization anneal to produce grain oriented electrical steel. A coating is applied overlying the surface, where the coating includes an organic radiation curable crosslinking agent and a photo-initiator. The coating is cured by exposing it to a radiation source.