1、Designation: A 721/A 721M 02Standard 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 of last revision.
2、 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 knownvariously as a ti
3、nners 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 exactequivalents; therefore,
4、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 of this standard
5、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:A 34/A 34M Practice for Sampling and Procurement Test-ing of Magnetic Materials2A 876/A 876M Specification for Flat-Rolled, Grain-Or
6、iented, Silicon-Iron, Electrical Steel, Fully ProcessedTypes2E 290 Test Methods for Bend Testing of Material forDuctility33. 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. The number
7、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 covered
8、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 approxim
9、ately 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 Two specim
10、ens 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 dimension of 3 i
11、n. 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 to the no
12、se 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 jurisdiction of ASTM
13、 Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A06.01 on TestMethods.Current edition approved Oct. 10, 2002. Published November 2002. Originallypublished as A 721 75. Last previous edition A 721 97.2Annual Book of ASTM Standards, Vol 03.04.3Annual Book of ASTM
14、Standards, Vol 03.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.4 Remove the specimen from the machine and withoutstraightening the bend, examine the outside face of the bend forsurface breaks, without magnification.7.5 Count
15、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 the larger number of breaks and poorer ductility.Class Rating C
16、ondition 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 breaks, all sizesClass 5 more than fifteen breaks, all sizes8.2
17、 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 converted number ofbreaks will then determine the class rating.8.
18、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 aclassification (not a numeric value). The procedure in this
19、 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 any patent rights asserted in connection with any item mentio
20、nedin 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 at any time by the responsible technical committee an
21、d 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 comments will receive careful consideration at a meeting o
22、f 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 by ASTM International, 100 Barr Harbor Drive, PO Box
23、 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 022
