ASTM A720-02(R2021) pdf free download

ASTM A720-02(R2021) pdf free download.Standard Test Method for Ductility of Nonoriented Electrical Steel
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, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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 ofreversals 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 E290. 4.2 This test is applicable to nonoriented silicon steel such as described in Specifications A677 and A683 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 ofa set ofstationary jaws and a movable arm to which is attached another set ofjaws 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 A34/A34M.
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 the direction of rolling and at least five at right angles to the direction of rolling. 7.2.2 When width of the material prevents cutting speci- mens at right angles to the direction of rolling, all specimens shall be cut in the direction ofrolling, and this shall be reported with the test results. 7.3 Edges of the test specimens shall be practically free of burrs; filing or machining to remove burrs is permissible.
8. Procedure
8.1 The specimen strips shall be at a temperature of 25 6 5°C at the start of the test. 8.2 Clamp the specimen tightly in the stationary jaws of the bend test machine, Fig. 1, and place in tension by stretching the spring during clamping. 8.3 Bend the specimen through 90° by use of the movable arm and jaws, Fig. 2; then bend it through 180° in the reverse direction. Again bend the specimen through 180° in the first direction and continually through 180° reversals until a crack appears at the bend or until sudden failure occurs by complete rupture. 8.4 Each full 180° bend, including the first 90° bend, shall be counted as one bend in determining the number of bends withstood by the specimen.