ASTM B593-21

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it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: B593 − 20 B593 − 21
Standard Test Method for
Bending Fatigue Testing for Copper-Alloy Spring Materials
This standard is issued under the fixed designation B593; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This test method establishes the requirements for the determination of the reversed or repeated bending fatigue properties of
copper alloy flat sheet,sheet or strip of spring materials by fixed cantilever, constant deflection (that is, constant amplitude of
displacement)-type testing machines. This method is limited to flat sheet or strip ranging in thickness from 0.005 in. to 0.062 in.
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(0.13 mm to 1.57 mm), to a fatigue life range of 10 to 10 cycles, and to conditions where no significant change in stress-strain
relations occurs during the test.
NOTE 1—This implies that the load-deflection characteristics of the material do not change as a function of the number of cycles within the precision of
measurement. There is no significant cyclic hardening or softening.
1.2 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.3 The following safety hazard caveat pertains only to the test methods(s) described in this test method.
1.3.1 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
B846 Terminology for Copper and Copper Alloys
B950 Guide for Editorial Procedures and Form of Product Specifications for Copper and Copper Alloys
E468 Practice for Presentation of Constant Amplitude Fatigue Test Results for Metallic Materials
E1823 Terminology Relating to Fatigue and Fracture Testing
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 Methods
of Test.
Current edition approved April 1, 2020Jan. 1, 2021. Published April 2020January 2021. Originally approved in 1973. Last previous edition approved in 20142020 as
ε1
B593–96 (2014)–20. . DOI: 10.1520/B0593–20.10.1520/B0593-21.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
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B593 − 21
2.2 Other ASTM Document:
ASTM STP 91-A91A A Guide for Fatigue Testing and the Statistical Analysis of Fatigue Data
3. Terminology
3.1 For definition of terms relating to this test method, refer to Terminology E1823 and Practice E468.
3.2 For definitions of terms related to copper and copper alloys, refer to Terminology B846.
4. Summary of Test Method
4.1 A prepared test specimen of a specific wrought copper alloy flat sheet or strip of spring material is mounted into a fixed
cantilever, constant-deflection type fatigue testing machine. The specimen is held at one end, acting as a cantilever beam, and
cycled by flexure followed by reverse flexure until complete failure. The number of cycles to failure is recorded as a measure of
fatigue life.
5. Significance and Use
5.1 The bending fatigue test described in this test method provides information on the ability of a copper alloy flat sheet and strip
of spring material to resist the development of cracks or general mechanical deterioration as a result of a relatively large number
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of cycles (generally in the range 10 to 10 ) under conditions of constant displacement.
5.2 This test method is primarily a research and development tool which may be used to determine the effect of variations in
materials on fatigue strength and also to provide data for use in selecting copper alloy spring materials for service under conditions
of repeated strain cycling.
5.3 The results are suitable for direct application in design only when all design factors such as loading, geometry of part,
frequency of straining, and environmental conditions are known. The test method is generally unsuitable for an inspection test or
a quality control test due to the amount of time and effort required to collect the data.
6. Apparatus
6.1 Testing Machine—The fatigue testing machine is a fixed-cantilever, constant-deflection type machine. In this machine (Fig. 1)
the test specimen shall be held as a cantilever beam in a clamp at one end and deflected by a concentrated load applied near the
other end of the apex of the tapered section (Fig. 2). Either the clamp or the loading member may be adjusted so that the deflection
of the free end of the cantilever is either completely reversed (mean displacement equal to zero) or greater in one direction of
bending (mean displacement not equal to zero).
6.2 A suitable counter and monitoring circuit is required to provide a direct readout of the number of cycles to complete failure;
thatfailure (that is, separation into two pieces.pieces).
7. Test Specimen
7.1 The test specimen shall be of the fixed-cantilever type. Examples of specimens that are typically used are shown in Fig. 2.
7.2 It is important, therefore, that care be exercised in the preparation of test specimens, particularly in machining, to
assureminimizing effects such as work hardening or induced stress. Conventional milling, blanking, or photochemical machining
can be used to ensure good workmanship. Improperly prepared test specimens cause unsatisfactory test results.
7.2.1 TheMilled specimens are best preparedmachined by cross milling a stack, approximately 0.75 in. (19.05 mm) thick,
including back-up plates, for which 0.12 in. (3.05 mm) thick brass sheet stock may be used.
7.2.1.1 It is necessary to ensure that any cutting or machining operation required to either rough cut the test specimen from the
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B593 − 21
FIG. 1 Fatigue Machines
blank, or to machine it to size does not appreciably alter the metallurgical structure or properties of the material. All cuts taken
in machining should be such as to minimize work hardening of the test specimen.
7.2.1.2 In selecting cutting speeds and feed rates, due regard should be paid to the test specimen material, and for finishing cuts,
to the quality of the surface finish required.
NOTE 2—It is not practicable to recommend a single procedure for feeds, speeds, and depth of cut, since this will vary with the material tested. The
procedure used, however, should be noted in reporting test results, since differences in procedure may produce variability in test results among different
laboratories.
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NOTE 1—All dimensions are in inches: in. × 25.4 = mm.
FIG. 2 Sheet or Strip Fatigue Test Specimens
7.2.2 Ph
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