1、Designation: A 721/A 721M 02 (Reapproved 2007)Standard Test Method forDuctility of Oriented Electrical Steel1This standard is issued under the fixed designation A 721/A 721M; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the ductility ofgrain-oriented silicon steel by use of an apparatus know
3、nvariously as a tinners brake, hand folder, or an apron brake.1.2 The values and equations stated in customary (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 exactequiva
4、lents; 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 does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user
5、 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 Standards:2A 34/A 34M Practice for Sampling and Procurement Test-ing of Magnetic MaterialsA 876 Specification for Flat-Rolle
6、d, Grain-Oriented,Silicon-Iron, Electrical Steel, Fully Processed TypesE 290 Test Methods for Bend Testing of Material forDuctility3. Summary of Test Method3.1 A test specimen representing the full width of grain-oriented steel to be tested is bent through an angle of about160 in a tinners brake. Th
7、e number of breaks, or fractures,occurring along the bend determines the ductility class rating.4. Significance and Use4.1 This is a specialized bend test for grain-oriented steelnot covered under the provisions of Test Methods E 290.4.2 This test is applicable to grain-oriented silicon steel suchas
8、 covered in Specifications A 876/A 876M in commercialthicknesses and widths up to 36 in. 910 mm.5. Apparatus5.1 The machine required to perform this test is knownvariously as a tinners brake, hand folder, or an apron brake.5.2 The brake shall be at least 36 in. 910 mm wide with anopening capacity of
9、 approximately 0.035 in. 0.9 mm.5.2.1 The nose bar shall have a 0.031-in. 0.8-mm radius.5.2.2 The bending bar must be movable through an angle ofat least 160.5.2.3 The movable table or apron shall move around the endof the nose bar at a distance of approximately 0.25 in. 6.35mm.6. Test Specimen6.1 T
10、wo specimens are required and they shall be selectedfrom the same general location as that of the magnetic testspecimens in accordance with Practice A 34/A 34M.6.2 The specimens shall be cut transversely to the rollingdirection and have a length equal to the sheet or strip width anda minimum dimensi
11、on of 3 in. 80 mm in the direction ofrolling.6.3 The specimens shall be free of rust, ripples, andscratches.7. Procedure7.1 The test specimen shall be at a temperature of 25 6 5Cat the start of the test.7.2 Insert the test specimen into the brake and clamp withthe direction of rolling perpendicular
12、to the nose bar and 0.5 to1.5 in. 12 to 40 mm under the nose bar thereby allowing thebalance of the specimen width to rest against the bending bar.7.3 Bend the specimen around the nose bar at a uniform rateby rotating the bending bar through an angle of 160.1This test method is under the jurisdictio
13、n of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of SubcommitteeA06.01 on TestMethods.Current edition approved Nov. 1, 2007. Published January 2008. Originallyapproved in 1975. Last previous edition approved in 2002 as A 721/A 721M02.2For referenced ASTM standards, visi
14、t the ASTM website, www.astm.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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-29
15、59, United States.Copyright by ASTM Intl (all rights reserved); Thu Jun 12 03:37:59 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.7.4 Remove the specimen from the machine and withoutstraightening the bend, examine the outside face of
16、 the bend forsurface breaks, without magnification.7.5 Count the breaks and measure for length.8. Interpretation of Results8.1 Classify each test specimen according to length ofnumber of breaks as shown in the following table which isbased on giving a larger numerical class rating correspondingto th
17、e larger number of breaks and poorer ductility.Class Rating Condition of BendClass 1 no breaksClass 2 not more than two breaks with totallength not exceeding 0.5 in.12.7 mmClass 3 three to eight breaks, all sizes or fewerbreaks with a total length exceed-ing 0.5 in. 12.7 mmClass 4 nine to fifteen br
18、eaks, all sizesClass 5 more than fifteen breaks, all sizes8.2 The class ratings shown are based on strip widths of 24to 36 in. 610 to 910 mm.8.3 When the evaluating steel narrower than 24 in. 610mm, the number of breaks should be multiplied by the ratio of24 over the strip width in inches. This conv
19、erted number ofbreaks will then determine the class rating.8.4 The class rating assigned to a test lot shall be the highernumerical class number of the two specimens.9. Precision and Bias9.1 It is not practicable to specify the precision of theprocedure in this test method because the test result is
20、 aclassification (not a numeric value). The procedure in this testmethod has no bias because the ductility classification isdefined only in terms of this test method.10. Keywords10.1 ductility; electrical; grain-oriented; silicon; steelASTM International takes no position respecting the validity of
21、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 responsibility.This standard is subject to r
22、evision 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. Yo
23、ur 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 the address shown below.This standard is cop
24、yrighted 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).A 721/A 721M 02 (2007)2Copyright by ASTM Intl (all rights reserved); Thu Jun 12 03:37:59 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.
