Abstract: An elastic matrix determination method and a vibration analysis method for a laminated iron core, with which it is possible to optimally determine an elastic modulus of a laminated iron core. When a vibration analysis of a laminated iron core obtained by laminating steel sheets is performed by using a configuration expression indicating a relationship between stress and strain in a matrix display by using an elastic matrix, a shear modulus in two surfaces including a laminating direction of the laminated iron core included in the elastic matrix in the configuration expression is determined in consideration of slip between laminated steel sheets.

Abstract: An elastic matrix determination method and a vibration analysis method for a laminated iron core, with which it is possible to optimally determine an elastic modulus of a laminated iron core. When a vibration analysis of a laminated iron core obtained by laminating steel sheets is performed by using a configuration expression indicating a relationship between stress and strain in a matrix display by using an elastic matrix, a shear modulus in two surfaces including a laminating direction of the laminated iron core included in the elastic matrix in the configuration expression is determined in consideration of slip between laminated steel sheets.

Abstract: According to the present invention, a grain oriented electrical steel sheet in which iron loss has been further reduced can be obtained by carrying out decarburization annealing as continuous annealing including: (1) heating the steel sheet to a temperature in the range of 700° C. to 750° C. at heating rate of 50° C./second or higher at least in a temperature range of 500° C. to 700° C. in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or lower than 0.05; (2) then cooling the steel sheet to a temperature range below 700° C. in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or lower than 0.05; and (3) reheating the steel sheet to a temperature in the range of 800° C. to 900° C. and retaining the steel sheet at the temperature for soaking in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or higher than 0.3.

Abstract: A directional electromagnetic steel sheet with a coating includes a directional electromagnetic steel sheet; and a coating that is formed on the surface of the directional electromagnetic steel sheet and contains elements P, Si, Cr and O as well as at least one element that is selected from the group consisting of Mg, Al, Ni, Co, Mn, Zn, Fe, Ca and Ba, with 5% by mass or more thereof being composed of a crystalline phase of a phosphate salt.

Abstract: According to the present invention, a grain oriented electrical steel sheet in which iron loss has been further reduced can be obtained by carrying out decarburization annealing as continuous annealing including: (1) heating the steel sheet to a temperature in the range of 700° C. to 750° C. at heating rate of 50° C./second or higher at least in a temperature range of 500° C. to 700° C. in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or lower than 0.05; (2) then cooling the steel sheet to a temperature range below 700° C. in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or lower than 0.05; and (3) reheating the steel sheet to a temperature in the range of 800° C. to 900° C. and retaining the steel sheet at the temperature for soaking in an atmosphere having oxidation potential P(H2O)/P(H2) equal to or higher than 0.3.