ASTM_A_721_-_A_721M_-_02_2016.pdf

Designation:A721/A721M02(Reapproved 2016)Standard Test Method forDuctility of Oriented Electrical Steel1This standard is issued under the fixed designation A721/A721M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year 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.1.Scope1.1 This test method covers determination of the ductility ofgrain-oriented silicon steel by use of an apparatus knownvariously 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 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 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 Documents2.1 ASTM Standards:2A34/A34M Practice for Sampling and Procurement Testingof Magnetic MaterialsA876 Specification for Flat-Rolled,Grain-Oriented,Silicon-Iron,Electrical Steel,Fully Processed TypesE290 Test Methods for Bend Testing of Material for Ductil-ity3.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 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 E290.4.2 This test is applicable to grain-oriented silicon steel suchas covered in Specification A876 in commercial thicknessesand 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 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 Two specimens are required and they shall be selectedfrom the same general location as that of the magnetic testspecimens in accordance with Practice A34/A34M.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 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 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 160.7.4 Remove the specimen from the machine and withoutstraightening the bend,examine the outside face of the bend forsurface breaks,without magnification.7.5 Count the breaks and measure for length.1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility 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 A721/A721M 02(2011).DOI:10.1520/A0721_A0721M-02R16.2For 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 standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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 RatingCondition of BendClass 1no breaksClass 2not more than two breaks with totallength not exceeding 0.5 in.12.7 mmClass 3three to eight breaks,all sizes or fewerbreaks with a total length exceed-ing 0.5 in.12.7 mmClass 4nine to fifteen breaks,all sizesClass 5more than fifteen breaks,all sizes8.2 The class ratings shown are based on strip widths of 24to 36 in.610 to 910