1、Designation: G204 10Standard 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 last rev
2、ision. 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 to this
3、 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 method i
4、s 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 behaviorof the r
5、eal 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 surfaces can
6、 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 corrosion.1. S
7、cope1.1 This test method covers the studying or ranking thesusceptibility of candidate materials to fretting corrosion orfretting wear for the purposes of material selection for appli-cations where fretting corrosion or fretting wear can limitserviceability.1.2 This test method uses a tribological b
8、ench test apparatuswith a mechanism or device that will produce the necessaryrelative motion between a contacting hemispherical rider and aflat counterface. The rider is pressed against the flat counter-face with a loading mass. The test method is intended for usein room temperature air, but future
9、editions could includefretting in the presence of lubricants or other environments.1.3 The purpose of this test method is to rub two solidsurfaces together under controlled fretting conditions and toquantify the damage to both surfaces in units of volume loss forthe test method.1.4 The values stated
10、 in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and h
11、ealth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2G40 Terminology Relating to Wear and ErosionG99 Test Method for Wear Testing with a Pin-on-DiskApparatusG133 Test Method for Linearly Reciprocating Ball-on-FlatSliding W
12、ear3. Terminology3.1 Definitions:3.1.1 fretting, nin tribology, small amplitude oscillatingmotion usually tangential between two solid surfaces in con-tact. G403.1.2 fretting corrosion, nform of fretting wear in whichcorrosion plays a significant role. G401This test method is under the jurisdiction
13、of ASTM Committee G02 on Wearand Erosion and is the direct responsibility of Subcommittee G02.40 on Non-Abrasive Wear.Current edition approved April 1, 2010. Published April 2010. DOI:10.1520/G020410.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
14、e at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.3 fretting wear, nwear arising as a result
15、 of fretting.G403.2 Definitions of Terms Specific to This Standard:3.2.1 coeffcient of variation (COV), ntest standard devia-tion divided by the test mean.3.2.2 counterface, nflat surface that the rider rubs on inthis test.3.2.3 crater, ncounterface damage in a fretting test froma hemispherical or s
16、pherical rider characterized by loss ofmaterial in the form of a surface depression.3.2.4 fretting amplitude, nsliding distance between direc-tion reversals (for example, if a dial indicator is used tomeasure stroke, the amplitude is the indicator movement on thedial).3.2.5 rider, nball or hemispher
17、e that oscillates on anothersurface to produce fretting damage.3.2.6 scar, ndamage to either rider or counterface in afretting test.4. Summary of Test Method4.1 This test method rubs a spherical or hemispherical solidrider on a solid flat under prescribed conditions to producefretting damage on one
18、or both surfaces. If damage occurs, it isquantified as a wear volume on each member and as systemwear, the sum of 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, isoptional.5. Significance and Use5.1
19、 Fretting wear and corrosion are potential serviceabilityfactors in many machines. They have always been factors inshipping finished goods by truck or rail. Packing materialsrubbing on a product in transit can make the product unsalable.Beverage cans and food cans can lose their trade dress andconsu
20、mers often equate container damage to content damage.5.2 Clamping surfaces on injection molds are damaged byfretting motions on clamping. This damage is a significantcause for mold replacement.5.3 Machines in shipment are subject to fretting damage inthe real area of contact of the bearings on the m
21、achines.5.4 Operating vibration and movement of mechanicallyclamped components, like screwed assemblies, can producedamage on the clamped faces and other faces that affectsmachine function or use. Many times fretting damage appearsin the form of pits, which are stress concentrators that can leadto m
22、echanical fractures.5.5 Electrical contacts in any device that is subject tovibration are susceptible to failure (open circuit) due to frettingdamage at real areas of contact.5.6 This test method is intended to be used to identifymating couples that may be less prone to fretting damage thanothers. T
23、his information in turn is used to select materials ofconstruction or surface treatments that are less prone to frettingdamage for applications where fretting conditions are known orperceived to exist.6. Apparatus6.1 Fig. 1 is a schematic of the test apparatus showingnecessary features. The schemati
24、c shows the counterfacemoving laterally with respect to the rider. The rider couldreciprocate with respect to the counterface as long as it still canmove in the downward direction to accommodate wear.6.2 The rider or counterface holder can be instrumented tosense friction force, but the device canno
25、t interfere withachieving the required relative motion between the rider andFIG. 1 Schematic of a Suitable Fretting Testing Riga = loading arm pivotb = counterface test specimenc = rider test specimend = device to measure rider movemente = device to measure counterface movementG204 102counterface. T
26、est rigs need instrumentation or a system toverify that the amplitude of oscillation is the test value of 50 62 m at test frequency.6.3 The test specimens must be affixed to the test rig in sucha manner that their movement in specimen clamps is less than1 m during testing.6.4 Wear in the specified t
27、est can be such that verticalmotion of the rider as wear occurs can be hundreds ofmicrometers. Thus, the test rig should be designed such that therider can move into the counterface at least 500 6 20 m.6.5 The test specimens should be protected from environ-mental contamination during testing and te
28、sting should be donein an atmosphere that stays consistent in nature throughout thetest. The standard test is performed in ordinary laboratory air at20C, 50 to 70% RH.6.6 The test rig shall be capable of an oscillating frequencyof 13 6 0.8 Hz (see Note 1). Most test rigs have variablefrequency capab
29、ility, and it is not usual to design a rig for awide frequency range. Mechanical actuators are usually ad-equate for frequencies in the range of 1 to 50 Hz. Higher testfrequencies usually require piezocrystals or the like as a sourceof oscillation. The standard test was developed using mechani-cal a
30、ctivation (electric motor driven crank).NOTE 1This frequency was chosen for convenience. It produces 106cycles in about 21.4 h. Users can do a test a day.7. Test Specimens7.1 The test specimens used in this test method can vary inshape as long as the rider has a 3.17 mm radius at the point ofcontact
31、 and the counterface is flat within 1 m per cm at thepoint of contact. The test specimens used in the development ofthis test method are shown in Fig. 2.7.2 Measuring wear scars with surface analysis instrumentscan be very challenging. The standard test was developed withsurface roughnesses on both
32、rider and counterface of less than0.1 m Ra. Surface finish can play a role in susceptibility tofretting damage. Polished surfaces produce the most succinctwear scars. Very rough surfaces ( 1 m Ra) may producehard-to-measure scars. Sometimes, only the rider wears; some-times only the counterface wear
33、s; sometimes both memberswear. Test Method G99 and G133 describe wear scar measure-ment in detail.7.3 Some surfaces of interest, like thermal spray deposits,are often incapable of being ground and lapped to thisroughness. They can be tested, but the users need to establishthe effect of excessive rou
34、ghness on repeatability. The COVmay be high for these test couples.7.4 The surface lay of the test specimens can affect resultsand care should be taken to produce non-directional lay in thecounterface and accurate curvature (no centerline protuberancegreater than 1 m on the rider). If test surfaces
35、have a distinctlay, the relationship of the rubbing to the lay (parallel orperpendicular) should be kept the same for each test couple.7.5 Grain direction can be a factor in both counterface andrider in crystalline materials. It is acceptable to ignore grainorientation in ground balls, but the grain
36、 orientation in thecounterface should simulate the application. The test wasdeveloped with counterfaces produced as flat-rolled steel andtesting was performed on the flat surfaces as opposed to endgrain.FIG. 2 Fretting Test SpecimensA = counterfaceB = rider (a ball may be adhered to a pin to make th
37、e rider)Surface roughness of both specimens = 0.1 m RaG204 1038. Procedure8.1 Clean test specimens of all films and particles. Ultra-sonic degreasing for 1 min in 100 mL of fresh acetone for eachspecimen has been determined to be adequate for metals. Cleanplastics and ceramics with techniques that d
38、o not contaminateor attack the test surface.8.2 Assemble specimens into the test rig after cleaningusing procedures that do not contaminate the testing surfaces.Affix the rider to the rider arm and the counterface to thecounterface holder. Gently lower the rider onto the counterfaceso there is no da
39、mage from this initial contact. Do not drop therider on the 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 similarsuch that the relative movement between the rider and coun-terface can be measured. Adjust the machine so that t
40、hisrelative motion is 50 6 2 m.8.4 When the required amplitude is achieved, commencetesting at 13 Hz (780 cycles/minute) and continue untilreciprocating 106cycles are completed (21.36 h) Use ultrason-ics or other processes to clean the debris from the frettingdamaged surfaces (for example, inhibited
41、 acid etch).8.5 Measure the wear volumes on both members. If a flat isworn on the spherical-shaped rider, the flat diameter can beused to calculate a wear volume using the formulas in the G99procedure for pin-on-disk testing. Counterface wear can usu-ally be measured by profilometer traces through t
42、he wearcrater; establish the cross-section area of the crater andcalculate the volume swept by revolution of this area or bysuitable other calculations. It is possible that one member ofthe test couple will not wear. It is also possible that onemember will adhere to the other such that the wear volu
43、me isreally a mass increase. Most often, both members wear.8.6 Use mass change to calculate specimen wear andconverted to volume using material densities, but the masschanges are usually so small that this technique may lead to ahigh COV, which is the test standard deviation divided by thetest mean.
44、 Volume calculation from scar dimensions is thepreferred technique.8.7 Calculate system friction coefficients for the test. Theywill likely vary during the test and the friction coefficientaveraging technique should be stated. The total friction energydissipated in the test (in joules) may be useful
45、, but it is anoptional test metric. This standard was developed withoutfriction measurement, since force measurement devices usuallydeflect to in order to sense force. Thus, this deflection must beconsidered in its effect on fretting amplitude. Three testreplicates are a minimum for each test couple
46、.9. Report9.1 See Fig. 3 for a sample test report. Be sure to include thewear volume of each member and the system wear volume.10. Precision and Bias10.1 There is no established absolute magnitude for thefretting wear value that occurs with a specific mating couple,so it is not possible to state a b
47、ias, but the following factorscould create a bias between different labs testing the samecouple under the same conditions:10.1.1 Specimens moved during testing, so the rubbingamplitude is different than planned.10.1.2 The dynamic fretting amplitude may be different thanthe amplitude measured at star
48、tup in jog mode.10.1.3 Specimens are contaminated in handling.10.1.4 Systemic errors in calculating wear volumes.10.1.5 Not adequately removing wear debris when measur-ing scar depths and dimensions.10.2 The repeatability of one lab using one material coupleis shown below:Test Rider Wear Volume Coun
49、terface Wear#8 24.27 3 10-122.36 3 10-12#9 24.27 3 10-122.11 3 10-12#11 24.27 3 10-121.57 3 10-12#12 26.68 3 10-121.65 3 10-12Rider average = 24.97 3 10-12,s+1.213 10-12, COV = 0.048Counterface average = 1.92 3 10-12,s=0.373 10-12,COV=0.1910.3 All volume losses are in cubic metres. The test couplewas Type 52100 steel rider at 60 HRC versus Type A2 toolsteel at 60 HRC counterface. The normal force was 10N; thefrequency was 11.66 Hz; the test amplitude was 50 m; therider radius was 3.17 mm. Rider wear was measured from scardiameter; counterface wear was measu
