ASTM G204-21

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Designation: G204 − 15 G204 − 21
Standard Test Method for
Damage to Contacting Solid Surfaces under Fretting
Conditions
This standard is issued under the fixed designation G204; 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.
INTRODUCTION
Fretting is small amplitude oscillating motion usually in the range of 1010 μm to 300 μm.
Contacting solid surfaces subjected to this type of motion can develop significant damage in the form
of mass loss, pitting, and debris generation, etc. generation. Frequently, pitting damage caused by
fretting creates stress concentrations that contribute to mechanical failures. Most material couples are
susceptible to fretting damage and this This test method is intended to assess a tribocouple’s relative
susceptibility to damage under fretting conditions.
When tribocouples experience oscillating relative motion less than about 10 μm, gross slip (all
points in a contact experience relative slip over a complete cycle) may not occur. The elastic behavior
of the real contacts may accommodate this motion and fretting damage may not occur.The onset of
fretting wear in a given tribocouple depends on factors such as the critical amplitude of slip, frequency
of oscillation, contact pressure, environment, cumulative cycles of oscillation, state of lubrication, and
contact geometry.
When metal couples are subjected to fretting motion, there is a potential for chemical reaction with
the ambient environment to be a component of the damage. In metals rubbing in air, oxidation of
freshly fractured surfaces can occur. When chemical reaction is conjoint with the mechanical damage
produced by fretting, it is called fretting corrosion. When most plastic (polymer) couples are damaged
by fretting motion, the fractured surfaces may not react with the environment and fretting wear occurs
as opposed to fretting corrosion.
1. Scope
1.1 This test method covers the studying or ranking the susceptibility of candidate materials to fretting corrosion or fretting wear
for the purposes of material selection for applications where fretting corrosion or fretting wear can limit serviceability.may be used
for either fundamental or applications-oriented studies of fretting damage. Accordingly, data from these tests may be used to rank
the wear resistance of candidate material couples for certain types of machine components whose service life is limited by fretting.
1.2 This test method uses a tribological bench test apparatus with a mechanism or device that will produce the necessary relative
motion between a contacting hemispherical rider and a flat counterface. The rider is pressed against the flat counterface with a
loading mass. The test method is intended for use in room temperature air, but future editions could include air. Other
configurations or test parameters may be needed to investigate fretting in the presence of lubricants or other environments.
1.3 The purpose of this test method is to rub two solid surfaces together under controlled fretting conditions and to quantify the
damage to both surfaces in units of volume loss for the test method.loss.
This test method is under the jurisdiction of ASTM Committee G02 on Wear and Erosion and is the direct responsibility of Subcommittee G02.40 on Non-Abrasive Wear.
Current edition approved Nov. 15, 2015June 1, 2021. Published December 2015July 2021. Originally approved in 2010. Last previous edition approved in 20102015 as
G204–10. DOI:10.1520/G0204–15.–15. DOI:10.1520/G0204-21.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G204 − 21
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 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:
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
G40 Terminology Relating to Wear and Erosion
G99 Test Method for Wear Testing with a Pin-on-Disk Apparatus
G117 Guide for Calculating and Reporting Measures of Precision Using Data from Interlaboratory Wear or Erosion Tests
(Withdrawn 2016)
G133 Test Method for Linearly Reciprocating Ball-on-Flat Sliding Wear
3. Terminology
3.1 Definitions:
3.1.1 fretting, n—in tribology, small amplitude oscillating motion usually tangential between two solid surfaces in contact. G40
3.1.2 fretting corrosion, n—form of fretting wear in which corrosion plays a significant role. G40
3.1.3 fretting wear, n—wear arising as a result of fretting. G40
3.2 Definitions of Terms Specific to This Standard:
3.2.1 coeffıcient of variation (COV), n—test standard deviation divided by the test mean.mean, sometimes expressed as a percent.
3.2.2 counterface, n—flat surface that the rider rubs on in this test.
3.2.3 crater, n—counterface damage in a fretting test from a hemispherical or spherical rider characterized by loss of material in
the form of a surface depression.
3.2.4 fretting amplitude, n—sliding distance between direction reversals (for example, if a dial indicator is used to measure stroke,
the amplitude is the indicator movement on the dial).
3.2.5 rider, n—ball or hemisphere that oscillates on another surface to produce fretting damage.
3.2.6 scar, n—damage to either rider or counterface in a fretting test.
3.2.7 system wear volume, n—the sum of the wear volume losses of the rider and the flat specimen.
4. Summary of Test Method
4.1 This test method rubs a spherical or hemispherical solid rider on a solid flat under prescribed conditions to produce fretting
damage on one or both surfaces. If damage occurs, it is quantified as a wear volume on each member and as system wear, the sum
of the rider and counterface wear.
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volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
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4.2 Friction forces can be measured during the fretting test, but these measurements, as well as reporting these data, is optional.
5. Significance and Use
5.1 Fretting wear and corrosion are potential serviceability factors in many machines. They have always been factors in shipping
finished goods by truck or rail. Packing materials rubbing on a product in transit can make the product unsalable. Beverage cans
and food cans can lose their trade dress and consumers often equate container damage to content damage.
5.2 Clamping surfaces on injection molds are damaged by fretting motions on clamping. This damage is a significant cause for
mold replacement.
5.3 Machines in shipment are subject to fretting damage in the real area of contact of the bearings on the machines.
5.4 Operating vibration and movement of mechanically clamped components, like screwed assemblies, can produce damage on
the clamped faces and other faces that affects machine function or use. Many times fretting damage appears in the form of pits,
which are stress concentrators that can lead to mechanical fractures.
5.5 Electrical contacts in any device that is subject to vibration are susceptible to failure (open circuit) due to fretting damage at
real areas of contact.
5.6 This test method is intended to be used to identify mating couples that may be less prone to fretting damage than others. This
information in turn is used to select materials of construction or surface treatments that are less prone to fretting damage for
applications where fretting conditions are known or perceived to exist.
5.7 When using this test method to screen candidate material pairs for a specific application, the user should ensure that the
prescribed geometry and test conditions described in Sections 6 – 8 adequately simulate the intended end use. The rationale for
any deviations from the prescribed test conditions, if any, shall be explained in the test report and, accordingly, the user shall report
that they used a modified version of the standard.
6. Apparatus
6.1 Fig. 1 is a schematic of the test apparatus showing necessary features. The schematic shows the counterface moving laterally
with respect to the rider. The rider could reciprocate with respect to the counterface as long as it still can move in the downward
direction to accommodate wear.
6.2 The rider or counterface holder can be instrumented to sense friction force, but the device cannot interfere with achieving the
required relative motion between the rider and counterface. Test rigs need instrumentation or a system to verify that the amplitude
of oscillation is the test value of 5050 μm 6 2 μm at test frequency.
6.3 The test specimens must be affixed to the test rig in such a manner that their movement in specimen clamps is less than 1 μm
during testing.
6.4 Wear in the specified test can be such that vertical motion of the rider as wear occurs can be hundreds of micrometers. Thus,
the test rig should be designed such that the rider can move into the counterface at least 500500 μm 6 20 μm.
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a = loading arm pivot
b = counterface test specimen
c = rider test specimen
d = device to measure rider movement
e = device to measure counterface movement
FIG. 1 Schematic of a Suitable Fretting Testing Rig
6.5 The test specimens should be protected from environmental contamination during testing and testing should be done in an
atmosphere that stays consistent in nature throughout the test. The standard test is performed in ordinary laboratory air at 20°C,
5020 °C, 50 % to 70%70 % RH.
6.6 The test rig shall be capable of an oscillating frequency of 1313 Hz 6 0.8 Hz (see Note 1). Most test rigs have variable
frequency capability, and it is not usual to design a rig for a wide frequency range. Mechanical actuators are usually adequate for
frequencies in the range of 11 Hz to 50 Hz. Higher test frequencies usually require piezocrystals o
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