Abstract: A wound core is formed by laminating a plurality of bent bodies formed from a grain-oriented electrical steel sheet having a coating containing phosphorus formed on a surface, in a sheet thickness direction of the grain-oriented electrical steel sheet, in which the bent body is formed in a rectangular shape by having four flat portions and four corner portions adjacent to the flat portions, the corner portion has a bent region having a total bending angle of approximately 90° in a side view, the number of deformation twins present in the bent region in the side view is five or less per 1 mm of a length of a center line in the bent region in the sheet thickness direction, and the amount of phosphorus eluted from the corner portion in a case of being boiled in water for 30 minutes is 6.0 mg or less per 1 m2 of a surface area of the corner portion.

Abstract: A wound core is formed by laminating a plurality of bent bodies formed from a grain-oriented electrical steel sheet having a coating containing phosphorus formed on a surface, in a sheet thickness direction of the grain-oriented electrical steel sheet, in which the bent body is formed in a rectangular shape by having four flat portions and four corner portions adjacent to the flat portions, the corner portion has a bent region having a total bending angle of approximately 90° in a side view, the number of deformation twins present in the bent region in the side view is five or less per 1 mm of a length of a center line in the bent region in the sheet thickness direction, and the amount of phosphorus eluted from the corner portion in a case of being boiled in water for 30 minutes is 6.0 mg or less per 1 m2 of a surface area of the corner portion.

Abstract: There is provided a method for manufacturing a grain-oriented electromagnetic steel sheet whose iron losses are reduced by laser beam irradiation, capable of improving the iron losses in both the L-direction and the C-direction while easily ensuring high productivity. The method for manufacturing a grain-oriented electromagnetic steel sheet reduces iron losses by scanning and irradiating a grain-oriented electromagnetic steel sheet with a continuous-wave laser beam condensed into a circular or elliptical shape at constant intervals in a direction substantially perpendicular to a rolling direction of the grain-oriented electromagnetic steel sheet, wherein when an average irradiation energy density Ua is defined as Ua=P/(Vc×PL) (mJ/mm2), where P (W) is average power of the laser beam, Vc (m/s) is a beam scanning velocity, and PL (mm) is an irradiation interval in a rolling direction, PL and Ua are in the following ranges: 1.0 mm?PL?3.0 mm, 0.8 mJ/mm2?Ua?2.0 mJ/mm2.

Abstract: There is provided a method for manufacturing a grain-oriented electromagnetic steel sheet whose iron losses are reduced by laser beam irradiation, capable of improving the iron losses in both the L-direction and the C-direction while easily ensuring high productivity. The method for manufacturing a grain-oriented electromagnetic steel sheet reduces iron losses by scanning and irradiating a grain-oriented electromagnetic steel sheet with a continuous-wave laser beam condensed into a circular or elliptical shape at constant intervals in a direction substantially perpendicular to a rolling direction of the grain-oriented electromagnetic steel sheet, wherein when an average irradiation energy density Ua is defined as Ua=P/(Vc×PL) (mJ/mm2), where P (W) is average power of the laser beam, Vc (m/s) is a beam scanning velocity, and PL (mm) is an irradiation interval in a rolling direction, PL and Ua are in the following ranges: 1.0 mm?PL?3.0 mm, 0.8 mJ/mm2?Ua?2.0 mJ/mm2.

Abstract: The present invention provides an electrical steel sheet core for a low-noise transformer capable of effectively lowering noise by suppressing vibration perpendicular to the surfaces of the steel sheets and reducing vibration, and relates to an electrical steel sheet for a low-noise transformer characterized by randomly inserting viscoelastic layers with both viscosity and elasticity into the gaps of the steel sheet lamination layers, and a low-noise transformer formed by using said electrical steel sheet.

Abstract: The present invention provides an electrical steel sheet core for a low-noise transformer capable of effectively lowering noise by suppressing vibration perpendicular to the surfaces of the steel sheets and reducing vibration, and relates to an electrical steel sheet for a low-noise transformer characterized by randomly inserting viscoelastic layers with both viscosity and elasticity into the gaps of the steel sheet lamination layers, and a low-noise transformer formed by using said electrical steel sheet.

Abstract: The present invention provides an electrical steel sheet core for a low-noise transformer capable of effectively lowering noise by suppressing vibration perpendicular to the surfaces of the steel sheets and reducing vibration, and relates to an electrical steel sheet for a low-noise transformer characterized by randomly inserting viscoelastic layers with both viscosity and elasticity into the gaps of the steel sheet lamination layers, and a low-noise transformer formed by using said electrical steel sheet.

Abstract: The present invention provides a wound core having a low core loss and not susceptible to a disappearance of the core loss lowering effect due to a magnetic domain refining even when stress-relief annealing is conducted after fabrication of a steel strip into a wound core, through a process which comprises, fabricating a very thin silicon steel strip comprising by 6.5% weight or less of silicon with the balance consisting essentially of iron and having a sheet thickness of 100 .mu.m or less and a magnetic flux density (B.sub.8 value) of 1.80T or more into a wound core, subjecting the wound core to stress-relief annealing, unwinding the very thin silicon steel strip from the core, introducing into the very thin silicon steel strip a linear or dotted local strain in a direction at an angle of 45.degree. to 90.degree. to the rolling direction of the thin strip, and rewinding the thin strip onto the core.