ASTM-A720/A720M:02(R2021) pdf free download – Standard Test Method for Ductility of Nonoriented Electrical Steel.
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 he less than tell.
7.2.1 The long axis of at least live test specimens shall he 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 specimens at right angles to the direction of rolling, all specimens shall be cut in the direction of rolling, 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 ± 5°C at the start of the Lest.
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 00 by use of the movable arm and jaws, Fig. 2; then bend it through 1 80° 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.
9. Calculations
9. 1 Express the ductility of the test lot or lift as the average of the number of bends withstood by the test specimens from that test lot or lift.
10. Precision and Bias
10.1 The procedure in this test method has no bias because the ductility rating determined is defined only in terms of this method. Although no rigorous interlaboratory comparisons of this test method have been conducted, it is estimated that the reproducibility standard deviation would not exceed 1 bend.
11. Keywords
11. 1 ductility; electrical: nonoriented: silicon; steel.