1、Designation: A 720/A 720M 02 (Reapproved 2007)Standard 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 y
2、ear 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. Scope1.1 This test method covers determination of ductility uti-lizing Epstein test strips and a bending device for ben
3、ding thestrip over 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 reg
4、arded separately asstandard. 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
5、.3 This standard does 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 Do
6、cuments2.1 ASTM Standards:2A 34/A 34M Practice for Sampling and Procurement Test-ing of Magnetic MaterialsA 677 Specification for Nonoriented Electrical Steel FullyProcessed TypesA 683/A 683M Specification for Nonoriented ElectricalSteel, Semiprocessed TypesE 290 Test Methods for Bend Testing of Mat
7、erial forDuctility3. 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
8、bend or 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 appli
9、cable to 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 wh
10、ich is attached 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 mo
11、ve freely 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
12、in each 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
13、 The test specimens shall be about 1.2 in. 30 mm inwidth and not less than 6 in. 150 mm in length.1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of SubcommitteeA06.01 on TestMethods.Current edition approved Nov. 1, 2007. Publi
14、shed January 2008. Originallyapproved in 1975. Last previous edition approved in 2002 as A 720/A 720M02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standard
15、s Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.2 The number of test specimens representing each test lotshall not be less than ten.7.2.1 The long axis of at least five test specimens shal
16、l 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 direction of rolling, all specimensshall be cut in the direction of rolling, and this shall be reportedwith the test result
17、s.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 of 25 65C at the start of the test.8.2 Clamp the specimen tightly in the stationary jaws of thebend test machine, Fig.
18、 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 reversedirection. Again bend the specimen through 180 in the firstdirection and continually through 180 reversals until a crack
19、appears 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 bendswithstood by the specimen.9. Calculations9.1 Express the ductility of the test lot or lift as the averageof the num
20、ber 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 determined is defined only in terms of thismethod. Although no rigorous interlaboratory comparisons ofthis test method have been
21、 conducted, it is estimated that thereproducibility standard deviation would not exceed 1 bend.11. Keywords11.1 ductility; electrical; nonoriented; silicon; steelASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this st
22、andard. 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 responsibility.This standard is subject to revision at any time by the responsible technical committee and must be rev
23、iewed 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 addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsi
24、ble 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 the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
25、onshohocken, 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 02 (2007)2
