ASTM E2948-16
(Test Method)Standard Test Method for Conducting Rotating Bending Fatigue Tests of Solid Round Fine Wire
Standard Test Method for Conducting Rotating Bending Fatigue Tests of Solid Round Fine Wire
SIGNIFICANCE AND USE
5.1 A method for obtaining fatigue strain (stress) at a specific life is of interest to the wire manufacturer, designer and consumer. The method is useful in production control, material acceptance and determination of the fatigue strain (stress) of the wire at a specific fatigue life, that is, fatigue strength. Rotating bending fatigue testing of small diameter solid round wire is possible by looping a specimen of predetermined length through an arc of 90° to 180°. The bending strain (stress) is determined from the geometry of the loop thusly formed. The methodology is capable of high frequency testing provided the temperature of the test article is constant and there is no adiabatic heating of the wire. A constant temperature can be maintained by immersing the specimen in a constant temperature fluid bath or test media. This makes it practical to quickly test a sufficient number of specimens to provide a statistical frequency distribution or survival probability distribution of fatigue life at a given strain (stress). Fatigue life information is useful to ascertain wire in-service durability and to assess, for example, the effects of melt practice and cold work processing.
SCOPE
1.1 This test method is intended as a procedure for the performance of rotating bending fatigue tests of solid round fine wire to obtain the fatigue strength of metallic materials at a specified life in the fatigue regime where the strains (stresses) are predominately and nominally linear elastic. This test method is limited to the fatigue testing of small diameter solid round wire subjected to a constant amplitude periodic strain (stress). The methodology can be useful in assessing the effects of internal material structure, such as inclusions, in melt technique and cold work processing studies. However, there is a caveat. The strain, due to the radial strain gradient imposed by the test methodology, is a maximum at the surface and zero at the centerline. Thus the test method may not seek out the “weakest link,” largest inclusions, that govern uniaxial high cycle fatigue life where the strain is uniform across the cross section and where fatigue damage initiates at a subsurface location (1-5).2 Also, pre-strain, which can influence fatigue life, is not included in this test method.
Note 1: The following documents, although not specifically mentioned, are considered sufficiently important to be listed in this test method:
ASTM STP 566 Handbook of Fatigue Testing
ASTM STP 588 Manual on Statistical Planning and Analysis for Fatigue Experiments
ASTM STP 731 Tables for Estimating Median Fatigue Limits (6-8)
1.2 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.
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Designation: E2948 − 16
StandardTest Method for
Conducting Rotating Bending Fatigue Tests of Solid Round
1
Fine Wire
This standard is issued under the fixed designation E2948; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
3
1.1 This test method is intended as a procedure for the 2.1 ASTM Standards:
E177Practice for Use of the Terms Precision and Bias in
performance of rotating bending fatigue tests of solid round
ASTM Test Methods
fine wire to obtain the fatigue strength of metallic materials at
E468Practice for Presentation of Constant Amplitude Fa-
aspecifiedlifeinthefatigueregimewherethestrains(stresses)
tigue Test Results for Metallic Materials
are predominately and nominally linear elastic. This test
E691Practice for Conducting an Interlaboratory Study to
method is limited to the fatigue testing of small diameter solid
Determine the Precision of a Test Method
round wire subjected to a constant amplitude periodic strain
F562 Specification for Wrought 35Cobalt-35Nickel-
(stress).Themethodologycanbeusefulinassessingtheeffects
20Chromium-10Molybdenum Alloy for Surgical Implant
of internal material structure, such as inclusions, in melt
Applications (UNS R30035)
technique and cold work processing studies. However, there is
E739PracticeforStatisticalAnalysisofLinearorLinearized
a caveat. The strain, due to the radial strain gradient imposed
Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
by the test methodology, is a maximum at the surface and zero
E1823TerminologyRelatingtoFatigueandFractureTesting
at the centerline. Thus the test method may not seek out the
4
2.2 ANSI Standard:
“weakest link,” largest inclusions, that govern uniaxial high
ANSI B4.1Standard Limits and Fits
cycle fatigue life where the strain is uniform across the cross
section and where fatigue damage initiates at a subsurface
3. Terminology
2
location (1-5). Also, pre-strain, which can influence fatigue
3.1 Definitions:
life, is not included in this test method.
3.1.1 Terms used in this practice shall be as defined in
NOTE 1—The following documents, although not specifically
Terminology E1823.
mentioned, are considered sufficiently important to be listed in this test
method:
4. Summary of Test Method
ASTM STP 566 Handbook of Fatigue Testing
4.1 Thistestmethodologydescribesameanstocharacterize
ASTM STP 588 Manual on Statistical Planning andAnalysis for Fatigue
Experiments the fatigue response of small diameter solid round wire using
ASTM STP 731 Tables for Estimating Median Fatigue Limits (6-8)
a rotating bending test. Small diameter wire, to be consistent
withSpecificationF562definitionof“finewire”,islessthanor
1.2 The values stated in inch-pound units are to be regarded
equal to a diameter of 0.063 in. (1.60 mm). The wire is
as standard. The values given in parentheses are mathematical
subjected to a constant-amplitude bending strain (stress) while
conversions to SI units that are provided for information only
it rotates at a fixed speed. This creates a fully reversed, R =
and are not considered standard.
(minimum strain (stress)/ maximum strain (stress))= –1, bend-
ing strain at any point on the circumference of the wire. The
number of revolutions or cycles is counted until a failure
1
This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
3
Deformation and Fatigue Crack Formation. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2016. Published June 2016. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2014. Last previous edition approved in 2014 as E2948–14. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E2948-16 the ASTM website.
2 4
The boldface numbers in parentheses refer to a list of references at the end of Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
this standard. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E2948 − 16
(fracture into two or more distinct pieces) is detected. Surface 6. Methods
effects due to environmental factors (for example corrosion or
6.1 Non-guidedorguidedrotatingbendingtests,orbothare
cavitation) can be extremely important in assessing fatigue
includedinthistestmethod.Typicaltestfrequencyrangesfrom
performance. Such
...
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 to the previous version. Because
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: E2948 − 14 E2948 − 16
Standard Test Method for
Conducting Rotating Bending Fatigue Tests of Solid Round
1
Fine Wire
This standard is issued under the fixed designation E2948; 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.
1. Scope
1.1 This test method is intended as a procedure for the performance of rotating bending fatigue tests of solid round fine wire
to obtain the fatigue strength of metallic materials at a specified life in the fatigue regime where the strains (stresses) are
predominately and nominally linear elastic. This test method is limited to the fatigue testing of small diameter solid round wire
subjected to a constant amplitude periodic strain (stress). The methodology can be useful in assessing the effects of internal
material structure, such as inclusions, in melt technique and cold work processing studies. However, there is a caveat. The strain,
due to the radial strain gradient imposed by the test methodology, is a maximum at the surface and zero at the centerline. Thus
the test method may not seek out the “weakest link,” largest inclusions, that govern uniaxial high cycle fatigue life where the strain
2
is uniform across the cross section and where fatigue damage initiates at a subsurface location (1-5). Also, pre-strain, which can
influence fatigue life, is not included in this test method.
NOTE 1—The following documents, although not specifically mentioned, are considered sufficiently important to be listed in this test method:
ASTM STP 566 Handbook of Fatigue Testing
ASTM STP 588 Manual on Statistical Planning and Analysis for Fatigue Experiments
ASTM STP 731 Tables for Estimating Median Fatigue Limits (6-8)
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the given in parentheses are mathematical conversions to SI units that are
provided for information only and are not considered standard.
2. Referenced Documents
3
2.1 ASTM Standards:
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E468 Practice for Presentation of Constant Amplitude Fatigue Test Results for Metallic Materials
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
F562 Specification for Wrought 35Cobalt-35Nickel-20Chromium-10Molybdenum Alloy for Surgical Implant Applications
(UNS R30035)
E739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (ε-N) Fatigue Data
E1823 Terminology Relating to Fatigue and Fracture Testing
4
2.2 ANSI Standard:
ANSI B4.1 Standard Limits and Fits
3. Terminology
3.1 Definitions:
3.1.1 Terms used in this practice shall be as defined in Terminology E1823.
1
This test method is under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
Deformation and Fatigue Crack Formation.
Current edition approved May 1, 2014May 1, 2016. Published July 2014June 2016. Originally approved in 2014. Last previous edition approved in 2014 as E2948–14.
DOI: 10.1520/E2948-1410.1520/E2948-16
2
The boldface numbers in parentheses refer to a list of references at the end of this standard.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
4
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E2948 − 16
4. Summary of Test Method
4.1 This test methodology describes a means to characterize the fatigue response of small diameter solid round wire using a
rotating bending test. Small diameter wire, to be consistent with Specification F562 definition of “fine wire”, is less than or equal
to a diameter of 0.063 in. (1.60 mm). The wire is subjected to a constant-amp
...
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