ASTM_B_820_-_14a.pdf

Designation:B82014aStandard Test Method forBend Test for Determining the Formability of Copper andCopper Alloy Strip1This standard is issued under the fixed designation B820;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method describes the technique of bend testingcopper and copper alloy strip samples to determine productformability or the ability to resist cracking when forming abend around a specific radius.The criterion for failure is theoccurrence of cracks on the outer radius of curvature(convex).1.2 This bend test is limited to strip from 0.003 to andincluding 0.031 in.thick(0.076 to and including 0.79 mm).1.3 The size of the forming radii used in this test shall be0.005 to and including 0.250 in.(0.127 to and including 6.35mm).1.4 UnitsValues stated in inch-pound units are to beregarded as standard.The values given in parentheses aremathematical conversions to SI units which are provided forinformation only and are not considered standard.1.5 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:2B846 Terminology for Copper and Copper AlloysB950 Guide for Editorial Procedures and Form of ProductSpecifications for Copper and Copper AlloysE6 Terminology Relating to Methods of Mechanical TestingE290 Test Methods for Bend Testing of Material for Ductil-ity3.Terminology3.1 For definitions of terms related to copper and copperalloys,refer to Terminology B846.3.2 For definitions of terms related to mechanical testing,refer to Terminology E6.3.3 Description of Terms Specific to This Standard:3.3.1 bend,longitudinal(or good way bend)a bend withan axis perpendicular to the direction of rolling,drawing orextrusion(see Fig.1).3.3.2 bend,transverse(or bad way bend)a bend with anaxis on a plane parallel to the direction of rolling,drawing orextrusion(see Fig.1).NOTE1The usage of these two terms is consistent with Test MethodsE290.4.Summary of Test Method4.1 The bend test is made by applying a force transverselyto the length of the specimen in the portion being bent,usuallyat mid-length.The 90 bending forces are applied through anarrangement illustrated in Fig.2,while 180 bending forces areapplied through an arrangement illustrated in Fig.3.Whencomplete fracture does not occur,the convex surface of thespecimen is examined for cracks.In general,the test using a180 bend angle is a more severe test than the test using a 90bend angle.5.Significance and Use5.1 This bend test provides information as to the formabilityor the ability of copper and copper alloy strip to resist crackingwhen being formed.5.2 This test method can be used as a quality control tool todetermine if material will form to a given radius.5.3 This test method is also useful in research and develop-ment to provide data for use in selecting a spring material thatwill safely form to the geometry of a given part.5.4 The results are suitable for direct application in designand manufacturing,only when all factors such as the geometryof the part,punch and die design,lubrication,stamping speed,and other material properties are known.6.Apparatus6.1 Various devices are suitable for 90 or 180 bendtesting.The apparatus shall provide these features:1This test method is under the jurisdiction of ASTM Committee B05 on Copperand Copper Alloys and is the direct responsibility of Subcommittee B05.06 onMethods of Test.Current edition approved Sept.1,2014.Published September 2014.Originallyapproved in 1992.Last previous edition approved in 2014 as B820 14.DOI:10.1520/B0820-14A.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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.1.1 90 Bend Test FixtureAn illustration of this testfixture is shown in Fig.2.A specimen rests on a pair of pins,rollers,or radiused flat supports;a pin,mandrel,or 90 V-blockpunch of a given bend radius for applying the bending forcedirectly at the mid-length.6.1.2 180 Bend Test FixtureAn illustration of this testfixture is shown in Fig.3.A specimen rests on a pair of pins,rollers,or radiused flat supports;a pin,mandrel,or 180 punchof a given bend radius for applying the bending force directlyat the mid-length.Dial indicators with a precision of 0.0005 in.(0.013 mm)or be