1、Designation: A720/A720M 02 (Reapproved 2016)1Standard Test Method forDuctility of Nonoriented Electrical Steel1This standard is issued under the fixed designation A720/A720M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year
2、 of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorially corrected designation in 2.1 in April 2016.1. Scope1.1 This test method covers determination of ductility uti
3、-lizing Epstein test strips and a bending device for bending 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 cus
4、tomary (cgs-emuand inch-pound) or SI units are to be regarded 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 sys
5、tems mayresult in nonconformance with this test method.1.3 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
6、 of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A34/A34M Practice for Sampling and Procurement Testingof Magnetic MaterialsA677 Specification for Nonoriented Electrical Steel FullyProcessed TypesA683 Specification for Nonoriented Electrical Steel, Semi-processed Ty
7、pesE290 Test Methods for Bend Testing of Material for Ductil-ity3. 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 thro
8、ugh 180 reversals until acrack appears at the 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 provision
9、s of Test Methods E290.4.2 This test is applicable to nonoriented silicon steel suchas described in Specifications A677 and A683 in commercialthicknesses.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
10、 jawsand a movable arm to which 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 s
11、hall allow thespecimen to move 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 tw
12、o well separated loca-tions 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 A34/A34M.1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct res
13、ponsibility of Subcommittee A06.01 on TestMethods.Current edition approved April 1, 2016. Published April 2016. Originallyapproved in 1975. Last previous edition approved in 2011 as A720/A720M 02(2011). DOI: 10.1520/A0720_A0720M-02R16E01.2For referenced ASTM standards, visit the ASTM website, www.as
14、tm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.1.2 Cut
15、 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 test 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
16、 than ten.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 direction of rolling, all specimensshall be cut in the di
17、rection 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 of 25 65C at the start of the test.8.2 Clamp the spe
18、cimen 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 reversedirection. Again bend the specimen through 180 in the
19、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 bendswithstood by the specimen.9. Calculations9.1 Expr
20、ess 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 determined is defined only in terms of thismethod. Although no
21、 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 takes no position respecting the validity of any pate
22、nt 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 responsibility.This standard is subject to revision
23、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 addressed to ASTM International Headquarters. Your comme
24、nts 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 the address shown below.This standard is copyrighted
25、 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-ma
26、il); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 1 Apparatus for Bend TestFIG. 2 Diagram Illustrating Method of Making BendsA720/A720M 02 (2016)12
