Designation: A 720/A 720M – 02
Standard Test Method for
Ductility of Nonoriented Electrical Steel
1
This standard is issued under the fixed designation A 720/A 720M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers determination of ductility uti-
lizing Epstein test strips and a bending device for bending the
strip over a predetermined radius. It is intended for commercial
silicon-bearing steel sheet or strip of nonoriented types in the
thickness range from 0.010 to 0.031 in. [0.25 to 0.79 mm],
inclusive.
1.2 The values and equations stated in customary (cgs-emu
and inch-pound) or SI units are to be regarded separately as
standard. Within this test method, SI units are shown in
brackets. The values stated in each system may not be exact
equivalents; therefore, each system shall be used independently
of the other. Combining values from the two systems may
result in nonconformance with this test method.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
A 34/A 34M Practice for Sampling and Procurement Test-
ing of Magnetic Materials
2
A 677/A 677M Specification for Nonoriented Electrical
Steel Fully Processed Types
2
A 683/A 683M Specification for Nonoriented Electrical
Steel, Semiprocessed Types
2
E 290 Test Methods for Bend Testing of Material for
Ductility
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3. Summary of Test Method
3.1 A test strip is placed in the special test apparatus
designed to clamp one end of the specimen securely while the
other end is free to move, but held in tension by a spring. The
specimen is repeatedly bent through 180° reversals until a
crack appears at the bend or until sudden failure occurs by
complete rupture. The number of reversals until failure is taken
as a measure of the ductility.
4. Significance and Use
4.1 This is a specialized bend test for nonoriented electrical
steel not covered under the provisions of Test Methods E 290.
4.2 This test is applicable to nonoriented silicon steel such
as described in Specifications A 677/A 677M and A 683/
A 683M in commercial thicknesses.
4.3 It is not intended to be applied to steels considered
inherently ductile.
5. Apparatus
5.1 The apparatus, Fig. 1, consists of a set of stationary jaws
and a movable arm to which is attached another set of jaws and
a spring.
5.1.1 The stationary jaws shall have working edges with
radii of approximately 0.2 in. [5 mm] over which the test
specimen is bent. Stationary jaws shall be of the quick-
clamping type.
5.1.2 The jaws attached to the movable arm shall allow the
specimen to move freely during bending.
5.1.3 The spring clamped to the free end of the specimen
shall provide sufficient tension in the specimen to localize the
bend.
5.1.4 Design of the movable arm shall permit a rotation of
approximately 180°.
6. Sampling
6.1 Select samples from at least two well separated loca-
tions in each test lot or lift.
6.1.1 The test specimens may be cut from samples used for
the core loss or other tests in accordance with the practice in
Practice A 34/A 34M.
6.1.2 Cut test specimens from near each end of each sample
coil and from the middle and the end of each sample sheet.
7. Test Specimen
7.1 The test specimens shall be about 1.2 in. [30 mm] in
width and not less than 6 in. [150 mm] in length.
7.2 The number of test specimens representing each test lot
shall not be less than ten.
7.2.1 The long axis of at least five test specimens shall be in
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This test method is under the jurisdiction of ASTM Committee A06 on
Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test
Methods.
Current edition approved Oct. 10, 2002. Published November 2002. Originally
published as A 720 – 75. Last previous edition A 720 – 97.
2
Annual Book of ASTM Standards, Vol 03.04.
3
Annual Book of ASTM Standards, Vol 03.01.
1
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