1、Designation: G204 10G204 15Standard Test Method forDamage to Contacting Solid Surfaces under FrettingConditions1This standard is issued under the fixed designation G204; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONFretting is small amplitude oscillating motion usually in the range of 10 to 300 m. Contacting solidsurfaces subjected
3、to this type of motion can develop significant damage in the form of mass loss,pitting, debris generation, etc. Frequently, pitting damage caused by fretting creates stress concentra-tions that contribute to mechanical failures. Most material couples are susceptible to fretting damageand this test m
4、ethod is intended to assess a tribocouples relative susceptibility to damage underfretting conditions.When tribocouples experience oscillating relative motion less than about 10 m, gross slip (allpoints in a contact experience relative slip over a complete cycle) may not occur. The elastic behavioro
5、f the real contacts may accommodate this motion and fretting damage may not occur.When metal couples are subjected to fretting motion, there is a potential for chemical reaction withthe ambient environment to be a component of the damage. In metals rubbing in air, oxidation offreshly fractured surfa
6、ces can occur. When chemical reaction is conjoint with the mechanical damageproduced by fretting, it is called fretting corrosion. When most plastic couples are damaged by frettingmotion, the fractured surfaces may not react with the environment and fretting wear occurs as opposedto fretting corrosi
7、on.1. Scope1.1 This test method covers the studying or ranking the susceptibility of candidate materials to fretting corrosion or fretting wearfor the purposes of material selection for applications where fretting corrosion or fretting wear can limit serviceability.1.2 This test method uses a tribol
8、ogical bench test apparatus with a mechanism or device that will produce the necessary relativemotion between a contacting hemispherical rider and a flat counterface. The rider is pressed against the flat counterface with aloading mass. The test method is intended for use in room temperature air, bu
9、t future editions could include fretting in the presenceof 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 thedamage to both surfaces in units of volume loss for the test method.1.4 The va
10、lues 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 responsibilityof the user of this standard to establish appropriate
11、 safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of
12、a Test Method1 This test method is under the jurisdiction ofASTM Committee G02 on Wear and Erosion and is the direct responsibility of Subcommittee G02.40 on Non-Abrasive Wear.Current edition approved April 1, 2010Nov. 15, 2015. Published April 2010December 2015. DOI:10.1520/G020410.Originally appro
13、ved in 2010. Last previous editionapproved in 2010 as G20410. DOI:10.1520/G020415.2 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
14、 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 to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that us
15、ers 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1G40 Terminology Relating to
16、 Wear and ErosionG99 Test Method for Wear Testing with a Pin-on-Disk ApparatusG117 Guide for Calculating and Reporting Measures of Precision Using Data from Interlaboratory Wear or Erosion TestsG133 Test Method for Linearly Reciprocating Ball-on-Flat Sliding Wear3. Terminology3.1 Definitions:3.1.1 f
17、retting, nin tribology, small amplitude oscillating motion usually tangential between two solid surfaces in contact. G403.1.2 fretting corrosion, nform of fretting wear in which corrosion plays a significant role. G403.1.3 fretting wear, nwear arising as a result of fretting. G403.2 Definitions of T
18、erms Specific to This Standard:3.2.1 coeffcient of variation (COV), ntest standard deviation divided by the test mean.3.2.2 counterface, nflat surface that the rider rubs on in this test.3.2.3 crater, ncounterface damage in a fretting test from a hemispherical or spherical rider characterized by los
19、s of materialin the form of a surface depression.3.2.4 fretting amplitude, nsliding distance between direction reversals (for example, if a dial indicator is used to measurestroke, the amplitude is the indicator movement on the dial).3.2.5 rider, nball or hemisphere that oscillates on another surfac
20、e to produce fretting damage.3.2.6 scar, ndamage to either rider or counterface in a fretting test.4. Summary of Test Method4.1 This test method rubs a spherical or hemispherical solid rider on a solid flat under prescribed conditions to produce frettingdamage on one or both surfaces. If damage occu
21、rs, it is quantified as a wear volume on each member and as system wear, the sumof the rider and counterface wear.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 Use5.1 Fretting wear and corrosion
22、are potential serviceability factors in many machines.They have always been factors in shippingfinished goods by truck or rail. Packing materials rubbing on a product in transit can make the product unsalable. Beverage cansand food cans can lose their trade dress and consumers often equate container
23、 damage to content damage.5.2 Clamping surfaces on injection molds are damaged by fretting motions on clamping. This damage is a significant cause formold 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 vib
24、ration and movement of mechanically clamped components, like screwed assemblies, can produce damage onthe 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.
25、5 Electrical contacts in any device that is subject to vibration are susceptible to failure (open circuit) due to fretting damageat 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 t
26、urn is used to select materials of construction or surface treatments that are less prone to fretting damage forapplications where fretting conditions are known or perceived to exist.6. Apparatus6.1 Fig. 1 is a schematic of the test apparatus showing necessary features. The schematic shows the count
27、erface moving laterallywith respect to the rider. The rider could reciprocate with respect to the counterface as long as it still can move in the downwarddirection to accommodate wear.6.2 The rider or counterface holder can be instrumented to sense friction force, but the device cannot interfere wit
28、h achievingthe required relative motion between the rider and counterface. Test rigs need instrumentation or a system to verify that theamplitude of oscillation is the test value of 50 6 2 m at test frequency.6.3 The test specimens must be affixed to the test rig in such a manner that their movement
29、 in specimen clamps is less than 1m 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 500 6 20 m.G204 1526.5 The te
30、st specimens should be protected from environmental contamination during testing and testing should be done in anatmosphere that stays consistent in nature throughout the test. The standard test is performed in ordinary laboratory air at 20C,50 to 70% RH.6.6 The test rig shall be capable of an oscil
31、lating frequency of 13 6 0.8 Hz (see Note 1). Most test rigs have variable frequencycapability, and it is not usual to design a rig for a wide frequency range. Mechanical actuators are usually adequate for frequenciesin the range of 1 to 50 Hz. Higher test frequencies usually require piezocrystals o
32、r the like as a source of oscillation. The standardtest was developed using mechanical activation (electric motor driven crank).NOTE 1This frequency was chosen for convenience. It produces 106 cycles in about 21.4 h. Users can do a test a day.7. Test Specimens7.1 The test specimens used in this test
33、 method can vary in shape as long as the rider has a 3.17 mm radius at the point of contactand the counterface is flat within 1 m per cm at the point of contact. The test specimens used in the development of this testmethod are shown in Fig. 2.7.2 Measuring wear scars with surface analysis instrumen
34、ts can be very challenging. The standard test was developed withsurface roughnesses on both rider and counterface of less than 0.1 m Ra. Surface finish can play a role in susceptibility to frettingdamage. Polished surfaces produce the most succinct wear scars. Very rough surfaces ( 1 m Ra) may produ
35、ce hard-to-measurescars. Sometimes, only the rider wears; sometimes only the counterface wears; sometimes both members wear. Test Method G99and G133 describe wear scar measurement in detail.7.3 Some surfaces of interest, like thermal spray deposits, are often incapable of being ground and lapped to
36、this roughness.They can be tested, but the users need to establish the effect of excessive roughness on repeatability. The COV may be high forthese test couples.7.4 The surface lay of the test specimens can affect results and care should be taken to produce non-directional lay in thecounterface and
37、accurate curvature (no centerline protuberance greater than 1 m on the rider). If test surfaces have a distinct lay,the relationship of the rubbing to the lay (parallel or perpendicular) should be kept the same for each test couple.7.5 Grain direction can be a factor in both counterface and rider in
38、 crystalline materials. It is acceptable to ignore grainorientation in ground balls, but the grain orientation in the counterface should simulate the application.The test was developed withcounterfaces produced as flat-rolled steel and testing was performed on the flat surfaces as opposed to end gra
39、in.8. Procedure8.1 Clean test specimens of all films and particles. Ultrasonic degreasing for 1 min in 100 mLof fresh acetone for each specimenhas been determined to be adequate for metals. Clean plastics and ceramics with techniques that do not contaminate or attack thetest surface.8.2 Assemble spe
40、cimens into the test rig after cleaning using procedures that do not contaminate the testing surfaces. Affix therider to the rider arm and the counterface to the counterface holder. Gently lower the rider onto the counterface so there is nodamage from this initial contact. Do not drop the rider on t
41、he flat.8.3 Load the rider on the flat with a normal force of 10 N. Cycle the test rig in “jog mode” for up to 100 cycles or similar suchthat the relative movement between the rider and counterface can be measured. Adjust the machine so that this relative motion is50 6 2 m.G204 1538.4 When the requi
42、red amplitude is achieved, commence testing at 13 Hz (780 cycles/minute) and continue until reciprocating106 cycles are completed (21.36 h) Use ultrasonics or other processes to clean the debris from the fretting damaged surfaces (forexample, inhibited acid etch).8.5 Measure the wear volumes on both
43、 members. If a flat is worn on the spherical-shaped rider, the flat diameter can be usedto calculate a wear volume using the formulas in the G99 procedure for pin-on-disk testing. Counterface wear can usually bemeasured by profilometer traces through the wear crater; establish the cross-section area
44、 of the crater and calculate the volumeswept by revolution of this area or by suitable other calculations. It is possible that one member of the test couple will not wear.It is also possible that one member will adhere to the other such that the wear volume is really a mass increase. Most often, bot
45、hmembers wear.8.6 Use mass change to calculate specimen wear and converted to volume using material densities, but the mass changes areusually so small that this technique may lead to a high COV, which is the test standard deviation divided by the test mean. Volumecalculation from scar dimensions is
46、 the preferred technique.8.7 Calculate system friction coefficients for the test. They will likely vary during the test and the friction coefficient averagingtechnique should be stated. The total friction energy dissipated in the test (in joules) may be useful, but it is an optional test metric.This
47、 standard was developed without friction measurement, since force measurement devices usually deflect to in order to senseforce. Thus, this deflection must be considered in its effect on fretting amplitude. Three test replicates are a minimum for each testcouple.9. Report9.1 See Fig. 3 for a sample
48、test report. Be sure to include the wear volume of each member and the system wear volume.10. Precision and Bias (Provisional)310.1 There is no established absolute magnitude The precision of this test method is based on an interlaboratory study ofG204for the fretting wear value that occurs with a s
49、pecific mating couple, so it is not possible to state a bias, but the followingfactors could create a bias between, Standard Test Method for Damage to Contacting Solid Surfaces under Fretting Conditions,conducted in 2013. Four laboratories participated in this study. Each of the labs reported three replicate test results for a single testcouple in light mineral oil. Every “test result” reported represents an individual determination. Except for the use of only fourlaboratories, Practice E691 different labs testingand Guide G117 the same couple under the s
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