1、Designation: B820 09B820 14Standard 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 determi
3、ne 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. (0.076 to and inclu
4、ding 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 UnitsThe values Values stated in inch-pound units are to be regarded as standard. The values given in parentheses aremathematical conversions to SI units t
5、hatwhich 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 determin
6、e the applicability 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 Testin
7、gE290 Test Methods for Bend Testing of Material for Ductility3. Terminology3.1 DefinitionsFor definitions of terms related to copper and copper alloys, refer to Terminology B846, and for definitions ofterms relating to mechanical testing, refer to Terminology E6.3.2 For definitions of terms related
8、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 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
9、a plane parallel to the direction of rolling, drawing orextrusion (see Fig. 1).NOTE 1The usage of these two terms is consistent with Test MethodMethods 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, us
10、ually atmid-length. The 90 bending forces are applied through an arrangement illustrated in Fig. 2, while 180 bending forces are applied1 This test method is under the jurisdiction of ASTM Committee B05 on Copper and Copper Alloys and is the direct responsibility of Subcommittee B05.06 on Methodsof
11、Test.Current edition approved April 1, 2009April 1, 2014. Published May 2009May 2014. Originally approved in 1992. Last previous edition approved in 19982009 asB820 04B820 09. 1. DOI: 10.1520/B0820-09.10.1520/B0820-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactAST
12、M Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This 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
13、 to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Su
14、mmary 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 States1through an arrangement illustrated in Fig. 3. When complete fracture does not occur, the convex surface of the specimen isexam
15、ined for cracks. In general, the test using a 180 bend angle is a more severe test than the test using a 90 bend angle.5. 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 tes
16、t method can be used as a quality control tool to determine if material will form to a given radius.5.3 This 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
17、 for direct application in design and manufacturing, only when all factors such as the geometry ofthe 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 bend testing. The apparatus shall provide
18、these features:6.1.1 90 Bend Test FixtureAn illustration of this test fixture is shown in Fig. 2. A specimen 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
19、Test FixtureAn illustration of this test fixture is shown in Fig. 3. A specimen rests on a pair of pins, rollers,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.
20、013 mm) or better are necessary to accurately position the twosupports.6.1.2.1 To prevent breaking the punch, 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).FIG. 1 DirectionDirectio
21、n of BendingFIG. 2 V-BlockV-Block and Punch for 90 Bend TestFIG. 3 FixtureFixture for 180 Bend TestB820 1426.2 The radius of the single pin, mandrel, or punch applying the bend force at the mid-length shall differ not more than 6 5 %65 % from the nominal value of the radius.6.3 The length of all pin
22、s, rolls, mandrels, and radius flats must exceed the width of the specimen; they must be strong enoughand 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, shearing, or stamping.7.3 T
23、he 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 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 ro
24、lling. A longitudinal orgood way bend will take a sharper bend radius than a transverse bend. This characteristic becomes more pronounced 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.
25、7.4.3 In a transverse bend (bad way bend) specimen, its length shall be perpendicular to the direction of rolling as indicated inFig. 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 thickn
26、ess shall be measured using a micrometer with a precision of 0.0001 in. (0.00254 mm).8. Procedure8.1 Direction of TestAll tests shall 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
27、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 dial 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 0.0
28、005 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. Release 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
29、 magnification of 30. (The appearance of orange peel or roughened surface does not constitute a crack.) Metallographiccross-section shall 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/
30、strip thickness). It shall bereferenced with the degree of bend (90 or 180) and test direction (longitudinal or transverse).10. Retest10.1 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 addition
31、al five test specimens. All of these specimens must pass the bend test.11. Precision and Bias11.1 No information is presented about either precision or bias of Test Method B820 for measuring formability of copper alloyspring material since the test result is nonquantitative.12. Keywords12.1 bend rad
32、ius; bend test; copper and copper alloy strip; formability test; fracture; longitudinal bend; mandrel; transverse bendB820 143SUMMARY OF CHANGESCommittee B05 has identified the location of selected principal changes to this standard since the last issue(practice that have been incorporated since the
33、 B820 04B820 09 1) that may impact the use of this standard.issue as follows (Approved April 1, 2009.)2014):(1) The specificationSection 1.4 was revised in many sectionsof the Scope and Section 3to comply with the selected wording in, Terminology Section, has been revised to reflect Guide B950.(2) M
34、inor 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 mandrel or punch.(5) Reworded 8.3.1 from double the strip thickness to a single strip thickness.ASTM International tak
35、es 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, are entirely their own re
36、sponsibility.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 standardsand should be address
37、ed 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 Committee on Standards, at the
38、 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).B820 144
