1、Designation: A 720/A 720M 02Standard Test Method forDuctility of Nonoriented Electrical Steel1This standard is issued under the fixed designation A 720/A 720M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revisi
2、on. 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. Scope1.1 This test method covers determination of ductility uti-lizing Epstein test strips and a bending device for bending thestrip over
3、 a predetermined radius. It is intended for commercialsilicon-bearing steel sheet or strip of nonoriented types in thethickness 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-emuand inch-pound) or SI units are to be regarded separately a
4、sstandard. Within this test method, SI units are shown inbrackets. The values stated in each system may not be exactequivalents; therefore, each system shall be used independentlyof the other. Combining values from the two systems mayresult in nonconformance with this test method.1.3 This standard d
5、oes not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility 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 Documents2.1 ASTM St
6、andards:A 34/A 34M Practice for Sampling and Procurement Test-ing of Magnetic Materials2A 677/A 677M Specification for Nonoriented ElectricalSteel Fully Processed Types2A 683/A 683M Specification for Nonoriented ElectricalSteel, Semiprocessed Types2E 290 Test Methods for Bend Testing of Material for
7、Ductility33. Summary of Test Method3.1 A test strip is placed in the special test apparatusdesigned to clamp one end of the specimen securely while theother end is free to move, but held in tension by a spring. Thespecimen is repeatedly bent through 180 reversals until acrack appears at the bend or
8、until sudden failure occurs bycomplete rupture. The number of reversals until failure is takenas a measure of the ductility.4. Significance and Use4.1 This is a specialized bend test for nonoriented electricalsteel not covered under the provisions of Test Methods E 290.4.2 This test is applicable to
9、 nonoriented silicon steel suchas 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 consideredinherently ductile.5. Apparatus5.1 The apparatus, Fig. 1, consists of a set of stationary jawsand a movable arm to which is a
10、ttached another set of jaws anda spring.5.1.1 The stationary jaws shall have working edges withradii of approximately 0.2 in. 5 mm over which the testspecimen is bent. Stationary jaws shall be of the quick-clamping type.5.1.2 The jaws attached to the movable arm shall allow thespecimen to move freel
11、y during bending.5.1.3 The spring clamped to the free end of the specimenshall provide sufficient tension in the specimen to localize thebend.5.1.4 Design of the movable arm shall permit a rotation ofapproximately 180.6. Sampling6.1 Select samples from at least two well separated loca-tions in each
12、test lot or lift.6.1.1 The test specimens may be cut from samples used forthe core loss or other tests in accordance with the practice inPractice A 34/A 34M.6.1.2 Cut test specimens from near each end of each samplecoil and from the middle and the end of each sample sheet.7. Test Specimen7.1 The tes
13、t specimens shall be about 1.2 in. 30 mm inwidth and not less than 6 in. 150 mm in length.7.2 The number of test specimens representing each test lotshall not be less than ten.1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of
14、Subcommittee A06.01 on TestMethods.Current edition approved Oct. 10, 2002. Published November 2002. Originallypublished as A 720 75. Last previous edition A 720 97.2Annual Book of ASTM Standards, Vol 03.04.3Annual Book of ASTM Standards, Vol 03.01.1Copyright ASTM International, 100 Barr Harbor Drive
15、, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.2.1 The long axis of at least five test specimens shall be inthe direction of rolling and at least five at right angles to thedirection of rolling.7.2.2 When width of the material prevents cutting speci-mens at right angles to the dire
16、ction of rolling, all specimensshall be cut in the direction of rolling, and this shall be reportedwith the test results.7.3 Edges of the test specimens shall be practically free ofburrs; filing or machining to remove burrs is permissible.8. Procedure8.1 The specimen strips shall be at a temperature
17、 of 25 65C at the start of the test.8.2 Clamp the specimen tightly in the stationary jaws of thebend test machine, Fig. 1, and place in tension by stretching thespring during clamping.8.3 Bend the specimen through 90 by use of the movablearm and jaws, Fig. 2; then bend it through 180 in the reversed
18、irection. Again bend the specimen through 180 in the firstdirection and continually through 180 reversals until a crackappears at the bend or until sudden failure occurs by completerupture.8.4 Each full 180 bend, including the first 90 bend, shallbe counted as one bend in determining the number of b
19、endswithstood by the specimen.9. Calculations9.1 Express the ductility of the test lot or lift as the averageof the number of bends withstood by the test specimens fromthat test lot or lift.10. Precision and Bias10.1 The procedure in this test method has no bias becausethe ductility rating determine
20、d is defined only in terms of thismethod. Although no rigorous interlaboratory comparisons ofthis test method have been conducted, it is estimated that thereproducibility standard deviation would not exceed 1 bend.11. Keywords11.1 ductility; electrical; nonoriented; silicon; steelASTM International
21、takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own
22、 responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be add
23、ressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at
24、 the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 1 Apparatus for Bend TestFIG. 2 Diagram Illustrating Method of Making BendsA 720/A 720M 022
