1、Designation: B820 14B820 14aStandard 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,
2、 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 testing copper and copper alloy strip samples to determ
3、ine productformability or the ability to resist cracking when forming a bend around a specific radius. The criterion for failure is the occurrenceof cracks on the outer radius of curvature (convex).1.2 This bend test is limited to strip from 0.003 to and including 0.031 in. thick.thick (0.076 to and
4、 including 0.79 mm).1.3 The size of the forming radii used in this test shall be 0.005 to and including 0.250 in. (0.127 to and including 6.35 mm).1.4 UnitsValues stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units which
5、are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the app
6、licability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B846 Terminology for Copper and Copper AlloysB950 Guide for Editorial Procedures and Form of Product Specifications for Copper and Copper AlloysE6 Terminology Relating to Methods of Mechanical TestingE290 Tes
7、t Methods for Bend Testing of Material for Ductility3. Terminology3.1 For definitions of terms related to copper and copper alloys, 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 b
8、end, longitudinal (or good way bend)a bend with an axis perpendicular to the direction of rolling, drawing or extrusion(see Fig. 1).3.3.2 bend, transverse (or bad way bend)a bend with an axis on a plane parallel to the direction of rolling, drawing orextrusion (see Fig. 1).NOTE 1The usage of these t
9、wo terms is consistent with Test Methods E290.4. Summary of Test Method4.1 The bend test is made by applying a force transversely to the length of the specimen in the portion being bent, usually atmid-length. The 90 bending forces are applied through an arrangement illustrated in Fig. 2, while 180 b
10、ending forces are appliedthrough an arrangement illustrated in Fig. 3. When complete fracture does not occur, the convex surface of the specimen isexamined for cracks. In general, the test using a 180 bend angle is a more severe test than the test using a 90 bend angle.1 This test method is under th
11、e jurisdiction of ASTM Committee B05 on Copper and Copper Alloys and is the direct responsibility of Subcommittee B05.06 on Methodsof Test.Current edition approved April 1, 2014Sept. 1, 2014. Published May 2014September 2014. Originally approved in 1992. Last previous edition approved in 20092014 as
12、B820 09.B820 14. DOI: 10.1520/B0820-14.10.1520/B0820-14A.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This
13、 document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior edition
14、s as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*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. U
15、nited States15. Significance and Use5.1 This bend test provides information as to the formability or 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 to determine if material will form to a given radius.5.3 Th
16、is test method is also useful in research and development to provide data for use in selecting a spring material that willsafely form to the geometry of a given part.5.4 The results are suitable for direct application in design and manufacturing, only when all factors such as the geometry ofthe part
17、, punch and die design, lubrication, stamping speed, and other material properties are known.6. Apparatus6.1 Various devices are suitable for 90 or 180 bend testing. The apparatus shall provide these features:6.1.1 90 Bend Test FixtureAn illustration of this test fixture is shown in Fig. 2. A specim
18、en rests on a pair of pins, rollers,or radiused flat supports; a pin, mandrel, or 90 V-block punch of a given bend radius for applying the bending force directly atthe mid-length.6.1.2 180 Bend Test FixtureAn illustration of this test fixture is shown in Fig. 3. A specimen rests on a pair of pins, r
19、ollers,or radiused flat supports; a pin, mandrel, or 180 punch of a given bend radius for applying the bending force directly at themid-length. Dial indicators with a precision of 0.0005 in. (0.013 mm) or better are necessary to accurately position the twosupports.6.1.2.1 To prevent breaking the pun
20、ch, it is recommended not to use a radius smaller than 12 the thickness of the material beingtested 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 applying the bend force at the mid-length shall differ not more than 65 %from
21、the nominal value of the radius.FIG. 1 Direction of BendingFIG. 2 V-Block and Punch for 90 Bend TestFIG. 3 Fixture for 180 Bend TestB820 14a26.3 The length of all pins, rolls, mandrels, and radius flats must exceed the width of the specimen; they must be strong enoughand sufficiently rigid to resist
22、 significant deformation.7. Test Specimens7.1 Five specimens are required for this test.7.2 The test specimens may be prepared by cutting, shearing, or stamping.7.3 The test specimens shall have a width of 12 6 116 in. (12.7 6 1.57 mm) and of any convenient length greater than 12 in.(12.7 mm) unless
23、 specified otherwise by purchaser.7.4 Direction of Specimen:7.4.1 The bending characteristics of a metal vary with the orientation of the bends to the direction of rolling. A longitudinal orgood way bend will take a sharper bend radius than a transverse bend. This characteristic becomes more pronoun
24、ced as the metalthickness increases.7.4.2 In a longitudinal (good way bend) specimen, its length shall be parallel to the direction of rolling as indicated in Fig. 1.7.4.3 In a transverse bend (bad way bend) specimen, its length shall be perpendicular to the direction of rolling as indicated inFig.
25、1.7.4.4 Unless stated otherwise, the length and width of rectangular specimens shall be in the plane of the two major dimensionsof the product.7.5 The specimen thickness shall be measured using a micrometer with a precision of 0.0001 in. (0.00254 mm).8. Procedure8.1 Direction of TestAll tests shall
26、be performed with the axis of the bend at 90 to the specimen length.8.2 90 Bend Test:8.2.1 Place the specimen between the supports and apply the bend force until the angle of bend reaches 90. Release the forceand examine the specimen.8.3 180 Bend Test:8.3.1 Adjust the specimen supports using the dia
27、l indicators. Move each support away from the test punch center-line (fullyclosed position) by a distance equal to the strip thickness plus the punch radius, plus 0.0005 in. (0.013 mm).8.3.2 Place the specimen between the supports and apply the bend force until an the angle of bend reaches 180. Rele
28、ase theforce and examine the specimen.8.4 Pass/Fail CriterionTo pass either the 90 or 180 bend test, all five specimens shall not exhibit any cracks when examinedat a magnification of 30. (The appearance of orange peel or roughened surface does not constitute a crack.) Metallographiccross-section sh
29、all be used as a referee method, examining at 150 magnification.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 test direction (longitudinal or transverse).10. Retest
30、10.1 If one out of the five test specimens fails, a retest is permitted. If more than one specimen fails, no retesting is permitted.10.2 A retest requires an additional five test specimens. All of these specimens must pass the bend test.11. Precision and Bias11.1 No information is presented about ei
31、ther precision or bias of Test Method B820 for measuring formability of copper alloyspring material and copper alloy strip since the test result is nonquantitative.12. Keywords12.1 bend radius; bend test; copper and copper alloy strip; formability test; fracture; longitudinal bend; mandrel; transver
32、se bendB820 14a3SUMMARY OF CHANGESCommittee B05 has identified the principal changes to this standard test method that have been incorporatedsince the B820 14 issue as follows (Approved Sept. 1, 2014):(1) In Section 11.1 the addition of the words “copper and” before the words “copper alloy,” and rep
33、lace “spring material” with theterm “strip.”SUMMARY OF CHANGESCommittee B05 has identified the principal changes to this standard practice test method that have beenincorporated since the B820 09 issue as follows (Approved April 1, 2014):(1) Section 1.4 of the Scope and Section 3, Terminology Sectio
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