This standard specifies the methods used for determining the resistivity, density and stacking factor of grain-oriented and non-oriented electrical steel strip and sheet. These quantities are necessary to establish the physical characteristics of the material. Moreover, the density is necessary to allow specified values of the magnetic polarization, resistivity and stacking factor to be determined.
Since these properties are functions of temperature, the measurements will be made at an ambient temperature of 23℃±5℃ except when specified in this document.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1183-3 Plastics - Methods for determining the density of non-cellular plastics - Part 3: Gas pyknometer method
IEC 60050-121 International electrotechnical vocabulary - Part 121: Electromagnetism
IEC 60050-221 International electrotechnical vo-cabulary - Part 221: Magnetic materials and components
IEC 60404-2 Magnetic materials - Part 2: Methods of measurement of the magnetic properties of electrical steel strip and sheet by means of an Epstein flame
IEC 60404-3 Magnetic materials - Part 3：Methods of measurement of the magnetic properties of electrical steel strip and sheet by means of a single sheet tester
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in IEC 60050-121, IEC 60050-221 and ISO 1183-3 apply.
4 Determination of the resistivity
4.1 General
Two methods for the determination of the resistivity of a test specimen are described in this clause; Method R1 using an Epstein strip specimen, and Method R2 using a rectangular sheet specimen.
Note: Method R2 is based on the van-der-Pauw (VDP) method [1] which is based on the theory of conformal mapping of two-dimensional fields. For a body of uniform thickness and arbitrary shape, an exact mathematical formula exists for the resistivity determined from the voltage to current ratio obtained using four contacts. The formula is simplified when specimens and contact positions are highly symmetrical. Method R2 is particularly appropriate for rectangular sheet specimens.
The method of determination of the resistivity ρ, based on the measurement of the geometric dimensions of the test specimen including the thickness, can be applied to all types of material specimens. However, the method for further use to determine the density ρm in accordance with 5.2 is restricted to the materials as specified in 5.1.
4.2 Principles of measurement
4.2.1 Method of determining ρ for an Epstein strip specimen (Method R1)
The circuit for the measurement of the resistance of an Epstein strip specimen shall be connected as shown in Figure 1. Two electrical contacts A and B shall be arranged on either end of the shorter sides of the test specimen to supply a homogeneous current through the test specimen in the longitudinal direction. Two electrical contacts, C and D, located inside the contacts A and B shall be arranged on a longer side edge of the test specimen to measure the voltage over the length le. It is not necessary to remove the oxide layer or other insulating coatings because the contacts are made at the cut edges of the specimen.
GB/T 19289-2019 The following standards are cited：
