1、Designation: B 820 04e1Standard 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
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEAn editorial change was made to subsection 1.3 in October 2004.1. Scope*1.1 This test method describes the techniq
3、ue 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
4、 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 UnitsThe values stated in inch-pounds are to beregarded as standard. The values given in pare
5、ntheses aremathematical conversions to SI units that 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-pria
6、te safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 The following documents in the current issue of theBook of Standards form a part of this specification to the extentreferenced herein:2.2 ASTM Standards:2B 846 Terminolog
7、y for Copper and Copper AlloysE 6 Terminology Relating to Methods of Mechanical Test-ingE 290 Test Method for Semi-Guided Bend Test for Ductilityof Metallic Materials3. Terminology3.1 DefinitionsFor definitions of terms related to copperand copper alloys, refer to Terminology B 846, and fordefinitio
8、ns of terms relating to mechanical testing, refer toTerminology E 6.3.2 Description of Terms Specific to This Standard:3.2.1 bend, 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 b
9、end with anaxis on a plane parallel to the direction of rolling, drawing orextrusion (see Fig. 1).NOTE 1The usage of these two 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 bei
10、ng bent, usuallyat midlength. 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, t
11、he 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
12、 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.1This test method is under the jurisdiction of ASTM Committee
13、 B05 on Copperand Copper Alloys and is the direct responsibility of Subcommittee B05.06 onMethods of Test.Current edition approved May 1, 2004. Published May 2004. Originallyapproved in 1992. Last previous edition approved in 1998 as B 820 98.2For referenced ASTM standards, visit the ASTM website, w
14、ww.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 Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive
15、, PO Box C700, West Conshohocken, PA 19428-2959, United States.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. Apparatus
16、6.1 Various devices are suitable for 90 or 180 bendtesting. The apparatus shall provide these features: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 give
17、n 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
18、 force directlyat the mid-length. Dial indicators with a precision of 0.0005 in.(0.013 mm) or better are necessary to accurately position thetwo supports.6.2 The radius of the single pin, mandrel, or punch applyingthe bend force at the mid-length shall differ not more than+5 % from the nominal value
19、.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 Five specimens are required for this test.7.2 The test specimens may be prepared by cutting, sh
20、ear-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 of Specimen:7.4.1 The bending characteristics of a metal vary with theorientation of the bends t
21、o 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 longitudinal (good way bend) specimen, its lengthshall be parallel to the direction of rolling as
22、 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 width ofrectangular specimens shall be in the plane of the two majordimensions of the product.7.5 T
23、he 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 specimen length.8.2 90 Bend Test:8.2.1 Place the specimen between the supports and applythe bend f
24、orce 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 center line (fullyclosed position) by a distance equal to twice the strip thicknessplus the pun
25、ch 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 CriterionTo pass either the 90 or 180bend test, all five specimens shall not exhibit any cracks
26、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 magnification.9. Report9.1 The results shall be reported as a minimum bend ratio(smallest passing b
27、end test radius/strip thickness). It shall bereferenced with the degree of bend (90 or 180) and testdirection (longitudinal or transverse).FIG. 1 Direction of BendingFIG. 2 V-Block and Punch for 90 Bend TestFIG. 3 Fixture for 180 Bend TestB82004e1210. Retest10.1 If one out of the five test specimens
28、 fails, a retest ispermitted. 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.11. Precision and Bias11.1 No information is presented about either precision orbias of Test Method B 820 fo
29、r 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; mandrel; trans-verse bendSUMMARY OF CHANGESCommittee B05 has identified the location o
30、f selected changes to this standard since the last issue (B 820 98)that may impact the use of this standard. (Approved May 1, 2004.)(1) Changed title and scope.(2) Increased the microscopes magnification from 10 to 303when examining the test specimens.(3) Added more keywords.(4) Made editorial chang
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34、our 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 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).B82004e13
