ASTM A720/A720M-02 (R2021) pdf free download.Standard Test Method for Ductility of Nonoriented Electrical Steel.
1.1 This test method covers determination of ductility utilizing 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. 10.25 to 0.79 mmj. 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 tesL method.
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 1800 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 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 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. 15 mmj 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(ions in each test lot or lift.
6. 1 . 1 The test specimens may he cut from samples used for the core loss or other tests in accordance with the practice in Practice A34/A34M.ASTM A720/A720M pdf download.