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GB/T 2521.2-2016 (GB/T2521.2-2016)

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GB/T 2521.2-2016English145 Add to Cart 0--3 minutes. Auto-delivery. Cold-rolled electrical steel delivered in the fully-processed state -- Part 2: Grain-oriented steel strip (sheet) Valid


GB/T 2521.2-2016: PDF in English (GBT 2521.2-2016)
GB/T 2521.2-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.40
H 53
Partially replacing GB/T 2521-2008
Cold-rolled Electrical Steel Delivered in the Fully-
processed State - Part 2: Grain-oriented Steel Strip (sheet)
(IEC 60404-8-7:2008, Magnetic Materials - Part 8-7: Specifications for Individual
Materials - Cold-rolled Grain-oriented Electrical Steel Strip and Sheet Delivered in the
Fully-processed State, MOD)
ISSUED ON: JUNE 14, 2016
IMPLEMENTED ON: MAY 1, 2017
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration Committee of the People’s
Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative References ... 5 
3 Terms and Definitions ... 6 
4 Classification ... 6 
5 Symbols and Designations ... 7 
6 General Requirements ... 8 
7 Technical Requirements ... 9 
8 Test and Inspection ... 15 
9 Determination and Re-inspection Rules ... 19 
10 Packaging, Mark and Quality Certificate ... 19 
11 Content of Order ... 19 
Appendix A (Normative) Repeated Bending Test Method ... 20 
Appendix B (Normative) Test Method of Coating Insulation Resistance ... 22 
Appendix C (Informative) Properties and Main Purposes of Various
Designations ... 23 
Appendix D (Informative) Comparison Table of Designations in this Part and
IEC 60404-8-7:2008 ... 25 
Appendix E (Informative) Comparison Table of Chapter Number in this Part and
IEC 60404-8-7:2008 ... 26 
Appendix F (Informative) Technical Differences and Reasons in this Part and
IEC 60404-8-7:2008 ... 28 
Cold-rolled Electrical Steel Delivered in the Fully-
processed State - Part 2: Grain-oriented Steel Strip (sheet)
1 Scope
This Part of GB/T 2521 specifies the terms, definitions, classification, symbols and
designations, general requirements, technical requirements, test and inspection,
determination and re-inspection rules, packaging, mark, quality certificate and content
of order of grain-oriented electrical steel strip (sheet) with the nominal thickness of 0.23
mm, 0.27 mm, 0.30 mm and 0.35 mm.
This Standard is applicable to grain-oriented electrical steel strip (sheet) [hereinafter
referred to as steel strip (sheet)] that is applied to magnetic circuit structure under fully-
processed cold-rolled delivered state.
2 Normative References
The following documents are indispensable to the application of this Standard. In terms
of references with a specified date, only versions with a specified date are applicable
to this Standard. The latest version (including all the modifications) of references
without a specified date is also applicable to this Standard.
GB/T 247 General Rule of Acceptance, Package, Mark and Certification for Steel
Plates (sheets) and Strips
GB/T 2522-2007 Methods of Test for the Determination of Surface Insulation
Resistance and Lamination Factor of Electric Sheet and Strip (IEC 60404-11:1999,
MOD)
GB/T 2900.60 Electrotechnical Terminology - Electromagnetism (GB/T 2900.60-
2002, eqv IEC 60050 (121):1998)
GB/T 3655 Methods of Measurement of the Magnetic Properties of Electrical Steel
Sheet and Strip by Means of an Epstein Frame (GB/T 3655-2008, IEC 60404-
2:1996, IDT)
GB/T 9637 Electrotechnical Terminology - Magnetic Materials and Components
[GB/T 9637-2001, eqv IEC 60050 (221):1990]
GB/T 13789 Methods of Measurement of the Magnetic Properties of Magnetic
Sheet and Strip by Means of a Single Sheet Tester (GB/T 13789-2008, IEC 60404-
3:2002, IDT)
GB/T 17505 Steel and Steel Products - General Technical Delivery Requirements
(GB/T 17505-2016, ISO 404:2013: MOD)
GB/T 18253 Steel and Steel Products - Types of Inspection Documents (GB/T
18253-2000, eqv ISO 10474:1991)
GB/T 19289 Methods of Measurement of Density, Resistivity and Stacking Factor
of Electrical Steel Sheet and Strip (GB/T 19289-2003, IEC 404-13:1995, MOD)
YB/T 4292 Methods of Determination of the Geometrical Characteristics of Electric
Steel Sheet and Strip (YB/T 4292-2012, IEC 60404-9:1987, MOD)
3 Terms and Definitions
Those defined in GB/T 2900.60, GB/T 9637 and YB/T 4292, and the following terms
and definitions are applicable to this Standard.
3.1 Number of Bends
Number of bends refers to the maximum number of repeated bends before substrate
manifests crack (or emits the sound of crack-generating) under visual observation.
NOTE: number of bends is utilized to signify the extensibility of a material.
3.2 Nominal Thickness Tolerance
Nominal thickness tolerance refers to the allowable tolerance of nominal thickness in
the same acceptance batch.
3.3 Longitudinal Thickness Tolerance
Longitudinal thickness tolerance refers to the thickness tolerance that is parallel to the
rolling direction of the previous steel sheet or on a certain length of steel strip.
3.4 Transverse Thickness Tolerance
Transverse thickness tolerance refers to the thickness tolerance that is vertical to the
rolling direction.
4 Classification
4.1 In this Part, the grade of steel strip (sheet) can be classified in accordance with the
maximum total loss ratio P1.7/50 under the magnetic polarization intensity of 1.7 T and
the frequency of 50 Hz, and the nominal thickness (0.23 mm, 0.27 mm, 0.30 mm and
0.35 mm) of steel strip (sheet). In addition, in accordance with the maximum total loss
as possible;
e) Strip slicing, or welding line might be generated by the elimination of defects.
Such strip slicing, or welding line shall be indicated; strip slicing, or welding line
shall be constituted of the same designation of steel. The number of strip slicing,
or welding line shall not exceed 2; the length of steel strip between 2 welding
lines shall be not less than 200 m;
f) The welding area shall be smooth and shall not affect the subsequent processing
of materials.
6.3 Conditions of Delivery
Generally speaking, steel strip (sheet) shall be delivered in trimmed condition. When
users have any special requirement, untrimmed condition of delivery is also allowable
through negotiation. Before delivery, steel strip (sheet) shall have insulated coating on
both sides. The type of insulating coating shall be determined by the supply side and
the demand side through negotiation.
6.4 Surface Quality
6.4.1 The surface of steel strip (sheet) shall be smooth and clean; there shall be no
corrosion. Scattered defects, such as scratch, bubble and crack, are allowed to exist
when they are within the range of thickness tolerance and do not affect the normal
utilization of the material.
6.4.2 The insulating coating on the surface of steel strip (sheet) shall be favorably
attached; the color of the coating shall be even, which guarantees that the coating will
not be stripped during the shearing operation and annealing under the stress relieving
and annealing conditions recommended by the manufacturer.
NOTE: if it is stipulated in the agreement that products shall be soaked in liquid, the
compatibility between the liquid and the coating needs to be guaranteed.
6.5 Shear Adaptability
It shall be convenient to shear steel strip. Steel strip shall be able to be sheared into a
normal shape in any position.
7 Technical Requirements
7.1 Magnetic Properties
7.1.1 The magnetic properties of steel strip (sheet) provided under the condition of 6.3
shall comply with the stipulation in Table 2, Table 3 and Table 4. Timeliness-based
sample shall also comply with these properties. In terms of products with coating, the
quality of the insulating coating shall be included in the calculation.
7.3.2 Stacking coefficient
The minimum stacking coefficient of steel strip (sheet) shall comply with the stipulation
in Table 2, Table 3 and Table 4.
7.3.3 Number of bends
The minimum number of bends of steel strip (sheet) that is parallel to the rolling
direction shall be not less than 1 time.
7.3.4 Tolerance of sheared edge triggered by internal stress
Internal stress on steel strip (sheet) shall be minimized. In accordance with the demand
side’s demand, and it shall be indicated in the contract, the tolerance test of sheared
edge that is triggered by internal stress can be conducted on steel strip (sheet) (after
longitudinal slitting) whose width is not less than 500 mm. The measured value of
welding seam shall not exceed 1 mm.
7.3.5 Insulation resistance of coating
In accordance with the demand side’s demand, and through the negotiation between
the demand side and the supply side, the test on the insulation resistance of coating
can be conducted. In addition, the minimum value of insulation resistance of the
coating surface or interlayer resistance shall be indicated in the contract. If steel strip
(sheet) needs thermal treatment, it shall be conducted in accordance with the
conditions appointed by the manufacturer. Furthermore, it shall be indicated in the
contract that insulation resistance of coating shall be tested before or after the thermal
treatment.
NOTE: insulation resistance of coating shall be divided into surface insulation resistance
and interlayer resistance.
8 Test and Inspection
8.1 General Requirements
8.1.1 When an agreement of ordering is signed in accordance with this Part, users can
conduct stipulated test and inspection in accordance with the stipulation in GB/T 17505,
or unstipulated test and inspection. However, in terms of unstipulated test and
inspection, the manufacturer shall provide the total loss ratio and magnetic polarization
intensity of steel strip (sheet).
8.1.2 When the ordered products are tested and inspected in accordance with the
stipulation, users shall be clear and definite about the type of inspection files in GB/T
18253.
8.1.3 Steel strip shall be batched in accordance with coil. Generally speaking, a coil
shall constitute a batch for acceptance.
8.1.4 Unless it is otherwise stipulated in an agreement, the stipulation in 8.1.3 is
applicable to the tolerance of sheared edge triggered by internal stress, shear
adaptability, insulation resistance of coating, geometrical characteristics and tolerance
inspection.
8.1.5 When products are delivered in the form of separated coils, the test result of the
original acceptance batch is applicable to the separated coils.
8.2 Sampling
8.2.1 General requirements
8.2.1.1 Sampling shall be taken from each acceptance batch.
8.2.1.2 The innermost ring and outermost ring of steel coil shall be deemed as
packaging material and shall not represent the quality of the whole steel coil. Sampling
shall not be taken from this part. Sampling shall avoid welding seam and splicing area.
8.2.1.3 Through reasonable arrangement of the test sequence, the same sub-sample
can be adopted for the test of multiple properties.
8.2.2 Magnetic properties
8.2.2.1 The sample for magnetic properties test shall be taken longitudinally that is
parallel to the rolling direction. Please see the specific requirements below:
a) When 25 cm Epstein square is adopted in the test, a set of samples shall be
constituted of 4 times of test pieces. The recommended weight is around 0.50
kg. The sampling method, dimension and allowable tolerance of sample shall
comply with the stipulation in GB/T 3655; before the test, stress relieving and
annealing shall be conducted on the sample under the conditions provided by
the manufacturer.
b) When single sheet tester is adopted, the sampling method, dimension and
allowable tolerance of the sample shall comply with the stipulation in GB/T
13789.
8.2.2.2 When the maximum total loss ratio of timeliness-based sample of steel strip
(sheet) is tested, the timeliness-based sample shall receive continuous heat
preservation at 225 °C ± 5 °C for 24 h, then, air-cooled to the ambient temperature.
8.2.3 Geometrical characteristics and tolerance
8.2.3.1 The sample for the test of thickness, width, unevenness and camber of steel
strip (sheet) shall be steel strip whose length is 2,000 mm or a steel sheet.
8.3.3.1 Thickness
The thickness of steel strip (sheet) shall be tested in any position that is at a distance
of not less than 30 mm from the edges of steel strip or steel sheet. In terms of material
whose width is less than 80 mm, the measurement of thickness shall be conducted on
the vertical axis of steel strip. The test of thickness shall adopt micrometer whose
division value is 0.001 mm.
8.3.3.2 Width
The width of steel strip (sheet) shall be tested along the vertical axis of vertical steel
strip or steel sheet.
8.3.3.3 Camber
The camber of steel strip (sheet) shall be tested in accordance with YB/T 4292.
8.3.3.4 Unevenness
The unevenness of steel strip (sheet) shall be tested in accordance with YB/T 4292.
8.3.3.5 Residual curvature
The residual curvature of steel strip (sheet) shall be tested in accordance with YB/T
4292.
8.3.3.6 The height of sheared burr
The height of sheared burr of steel strip (sheet) shall be tested in accordance with YB/T
4292.
8.3.4 Technical properties
8.3.4.1 Stacking coefficient
The stacking coefficient of steel strip (sheet) shall be tested in accordance with GB/T
19289.
8.3.4.2 Number of bends
The number of bends of steel strip (sheet) shall be tested in accordance with Appendix
A.
8.3.4.3 Tolerance of sheared edge triggered by internal stress
The tolerance of sheared edge triggered by internal stress of steel strip (sheet) shall
be tested in accordance with YB/T 4292.
8.3.4.4 Insulation resistance of coating
Appendix A
(Normative)
Repeated Bending Test Method
A.1 Sample
Along the rolling direction and avoid the edges of the base material, take a rectangular
sample whose minimum width is 20 mm (general width: 30 mm) and whose length is
250 mm ~ 300 mm. The number of the samples shall be not less than 2. The samples
shall be kept smooth.
A.2 Test Method
A.2.1 The test shall be conducted at the temperature of 23 °C ± 5 °C.
A.2.2 The sample shall be fixated with a lower clamp whose corner radius is 5 mm, as
it is shown in Figure A.1.
A.2.3 The method of counting repeated bends: bending to 90° from the initial position
and returning to the initial position shall be counted as a bend; bending 90° from the
initial position towards the other direction and returning to the initial position shall be
counted as another bend. Count the number of bends in turn.
A.2.4 Continuously bend the sample, until crack emerges (or the sample emits the
sound of crack-generating) for the first time under visual inspection, then, stop the test.
The last bend shall not be counted into the number of bends.
A.3 Test Device
In order to guarantee that the sample can be bended in a fixed position, impose certain
tension on the sample. The recommended tension is approximately 70 N. Please refer
to Figure A.2 for the repeated bending test device.
A.4 Test Result
The minimum value of several test results shall be considered as the ultimate test
result.
......
 
(Above excerpt was released on 2018-10-26, modified on 2022-10-12, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT2521.2-2016