1、Designation: B 820 09Standard Test Method forBend Test for Determining the Formability of Copper andCopper Alloy Strip1This standard is issued under the fixed designation B 820; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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 pro
3、ductformability 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 0.7
4、9 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 UnitsThe values stated in inch-pound units are to beregarded as standard. The values given in parentheses aremathematical conversions to SI units that are provided f
5、orinformation 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
6、regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 846 Terminology for Copper and Copper AlloysB 950 Guide for Editorial Procedures and Form of ProductSpecifications for Copper and Copper AlloysE6 Terminology Relating to Methods of Mechanical Test-ingE 290 Test Methods
7、for Bend Testing of Material forDuctility3. Terminology3.1 DefinitionsFor definitions of terms related to copperand copper alloys, refer to Terminology B 846, and fordefinitions of terms relating to mechanical testing, refer toTerminology E6.3.2 Description of Terms Specific to This Standard:3.2.1 b
8、end, longitudinal (or good way bend)a bend withan axis perpendicular to the direction of rolling, drawing orextrusion (see Fig. 1).3.2.2 bend, transverse (or bad way bend)a bend with anaxis on a plane parallel to the direction of rolling, drawing orextrusion (see Fig. 1).NOTE 1The usage of these two
9、 terms is consistent with Test MethodE 290.4. 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 bendin
10、g 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 t
11、est 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
12、-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,a
13、nd other material properties are known.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 April 1, 2009. Published May 2009. Originallyapproved in 1992. Last p
14、revious edition approved in 1998 as B 820 041.2For 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.1*A Summary of
15、Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Various devices are suitable for 90 or 180 bendtesting. The apparatus shall provide these features:6.1.1 90 Bend Test
16、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
17、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 better are necessary to accu
18、rately position thetwo supports.6.1.2.1 To prevent breaking the punch, it is recommendednot to use a radius smaller than12 the thickness of the materialbeing tested and in no case should the punch size be less than.005 in. (0.127 mm).6.2 The radius of the single pin, mandrel, or punch applyingthe be
19、nd force at the mid-length shall differ not more than 65 % from the nominal value of the radius.6.3 The length of all pins, rolls, mandrels, and radius flatsmust exceed the width of the specimen; they must be strongenough and sufficiently rigid to resist significant deformation.7. Test Specimens7.1
20、Five specimens are required for this test.7.2 The test specimens may be prepared by cutting, shear-ing, or stamping.7.3 The test specimens shall have a width of12 6116 in.(12.7 6 1.57 mm) and of any convenient length greater than12in. (12.7 mm) unless specified otherwise by purchaser.7.4 Direction o
21、f Specimen:7.4.1 The bending characteristics of a metal vary with theorientation of the bends to the direction of rolling. A longitu-dinal or good way bend will take a sharper bend radius than atransverse bend. This characteristic becomes more pronouncedas the metal thickness increases.7.4.2 In a lo
22、ngitudinal (good way bend) specimen, its lengthshall be parallel to the direction of rolling as indicated in Fig.1.7.4.3 In a transverse bend (bad way bend) specimen, itslength shall be perpendicular to the direction of rolling asindicated in Fig. 1.7.4.4 Unless stated otherwise, the length and widt
23、h ofrectangular specimens shall be in the plane of the two majordimensions of the product.7.5 The specimen thickness shall be measured using amicrometer with a precision of 0.0001 in. (0.00254 mm).8. Procedure8.1 Direction of TestAll tests shall be performed with theaxis of the bend at 90 to the spe
24、cimen length.8.2 90 Bend Test:8.2.1 Place the specimen between the supports and applythe bend force until the angle of bend reaches 90. Release theforce and examine the specimen.8.3 180 Bend Test:8.3.1 Adjust the specimen supports using the dial indicators.Move each support away from the test punch
25、center-line (fullyclosed position) by a distance equal to the strip thickness plusthe punch radius, plus 0.0005 in. (0.013 mm).8.3.2 Place the specimen between the supports and applythe bend force until an the angle of bend reaches 180. Releasethe force and examine the specimen.8.4 Pass/Fail Criteri
26、onTo pass either the 90 or 180bend test, all five specimens shall not exhibit any cracks whenexamined at a magnification of 303. (The appearance oforange peel or roughened surface does not constitute a crack.)Metallographic cross-section shall be used as a referee method,examining at 1503 magnificat
27、ion.9. Report9.1 The results shall be reported as a minimum bend ratio(smallest passing bend test radius/strip thickness). It shall bereferenced with the degree of bend (90 or 180) and testdirection (longitudinal or transverse).10. Retest10.1 If one out of the five test specimens fails, a retest isp
28、ermitted. If more than one specimen fails, no retesting ispermitted.10.2 A retest requires an additional five test specimens. Allof these specimens must pass the bend test.FIG. 1 Direction of BendingFIG. 2 V-Block and Punch for 90 Bend TestFIG. 3 Fixture for 180 Bend TestB82009211. Precision and Bia
29、s11.1 No information is presented about either precision orbias of Test Method B 820 for measuring formability of copperalloy spring material since the test result is nonquantitative.12. Keywords12.1 bend radius; bend test; copper and copper alloy strip;formability test; fracture; longitudinal bend;
30、 mandrel; trans-verse bendSUMMARY OF CHANGESCommittee B05 has identified the location of selected changes to this standard since the last issue(B 820 041) that may impact the use of this standard. (Approved April 1, 2009.)(1) The specification was revised in many sections to complywith the selected
31、wording in Guide B 950.(2) Minor editorial changes to 1.4, 2.1 (changed 2.2 to 2.1).(3) Added 6.1.2.1 which recommends how to avoid tool(punch) breakage.(4) Clarification in 6.2 on the radius tolerance of the mandrelor punch.(5) Reworded 8.3.1 from double the strip thickness to a singlestrip thickne
32、ss.ASTM International takes no position respecting the validity of 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,
33、are entirely their own responsibility.This standard is subject to revision 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 stan
34、dardsand should be addressed to ASTM International Headquarters. Your 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 Comm
35、ittee on Standards, at the address shown below.This standard is copyrighted 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).B820093
