1、Designation: G40 15Standard Terminology Relating toWear and Erosion1This standard is issued under the fixed designation G40; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates
2、 the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 The terms and their definitions given herein representterminology relating to wear and erosion of solid bodies due tomechanical interactions such as occur with cavitati
3、on, im-pingement by liquid jets or drops or by solid particles, orrelative motion against contacting solid surfaces or fluids. Thisscope interfaces with but generally excludes those processeswhere material loss is wholly or principally due to chemicalaction and other related technical fields as, for
4、 instance,lubrication.1.2 This terminology is not exhaustive; the absence of anyparticular term from this collection does not necessarily implythat its use within this scope is discouraged. However, theterms given herein are the recommended terms for the conceptsthey represent unless otherwise noted
5、.1.3 Certain general terms and definitions may be restrictedand interpreted, if necessary, to make them particularly appli-cable to the scope as defined herein.1.4 The purpose of this terminology is to encourage unifor-mity and accuracy in the description of test methods anddevices and in the report
6、ing of test results in relation to wearand erosion.NOTE 1All terms are listed alphabetically. When a subsidiary term isdefined in conjunction with the definition of a more generic term, analphabetically-listed cross-reference is provided.2. Referenced Documents2.1 ASTM Standards:2C242 Terminology of
7、 Ceramic Whitewares and RelatedProducts3. Terminologyabradant, na material that is producing, or has produced,abrasive wear.abrasion, nin tribology, the process by which relativemotion between a surface and hard particles or protuber-ances on an opposing surface produces abrasive wear of thatsurface
8、. (See also abrasive wear.)abrasive wear, nwear due to hard particles or hard protu-berances forced against and moving along a solid surface.abrasion-corrosion, na synergistic process involving bothabrasive wear and corrosion in which each of these processesis affected by the simultaneous action of
9、the other and, inmany cases, is thereby accelerated.abrasivity, nthe ability of a material or substance to causeabrasive wear.absolute impact velocitySee impact velocity.acceleration period, nin cavitation and liquid impingementerosion, the stage following the incubation period duringwhich the erosi
10、on rate increases from near zero to amaximum value. (See also erosion rate-time pattern.)accumulation period, nin cavitation and liquid impinge-ment erosion, a less-preferred term for acceleration period.adhesive wear, nwear due to localized bonding betweencontacting solid surfaces leading to materi
11、al transfer be-tween the two surfaces or loss from either surface.angle of attack, nin impingement erosion, the angle betweenthe direction of motion of an impinging liquid or solidparticle and the tangent to the surface at the point of impact.angle of incidence, nin impingement erosion, the anglebet
12、ween the direction of motion of an impinging liquid orsolid particle and the normal to the surface at the point ofimpact.apparent area of contact, nin tribology, the area of contactbetween two solid surfaces defined by the boundaries of theirmacroscopic interface. (Contrast with real area of contact
13、.)asperity, nin tribology, a protuberance in the small-scaletopographical irregularities of a solid surface.attenuation period, nin cavitation and liquid impingementerosion, a less-preferred term for deceleration period.average erosion rate, na less preferred term for cumulativeerosion rate. (See al
14、so interval erosion rate.)1This terminology is under the jurisdiction of ASTM Committee G02 on Wearand Erosion and is the direct responsibility of Subcommittee G02.91 on Terminol-ogy.Current edition approved Nov. 1, 2015. Published November 2015. Originallyapproved in 1973. Last previous edition app
15、roved in 2013 as G40 13. DOI:10.1520/G0040-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM
16、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Beilby layer, nan altered surface layer of supposedly amor-phous material formed on a crystalline solid during mechani-cal polishing, whose existence was proposed in Sir GeorgeBeilbys writings. The exi
17、stence of such a layer is notsupported by recent research, and the use of this term istherefore considered archaic and is strongly discouraged.bio-tribocorrosion, nin the field of medical devices anddental restoratives, a form of tribocorrosion in which bio-logical substances make up one or more of
18、the triboelementsor are present in the contact region between them.break-in, nSee run-in.break in, vSee run in.brinelling, ndamage to a solid bearing surface characterizedby one or more plastically formed indentations caused bystatic or impulsive overloads, especially as found in rollingcontact bear
19、ings. (See also false brinelling.)brittle erosion behavior, nerosion behavior having charac-teristic properties that can be associated with brittle fractureof the exposed surface; that is, little or no plastic flow occurs,but cracks form that eventually intersect to create erosionfragments. (See als
20、o ductile erosion behavior.)DISCUSSIONIn solid impingement an easily observable aspect oferosion helps to distinguish brittle from ductile behavior. This is themanner in which volume removal varies with the angle of attack. Withbrittle erosion the maximum volume removal occurs at an angle near90, in
21、 contrast to approximately 25 for ductile erosion behavior.carrier fluid, nin impingement or slurry erosion, fluidmedium that transports impinging solid or liquid particlesand that gives the particles their momentum relative to thesolid surface on which they are impinging.catastrophic period, nin ca
22、vitation or liquid impingementerosion, a stage during which the erosion rate increases sodrastically that continued exposure threatens or causes grossdisintegration of the exposed surface. This stage is notinevitable; it is observed most commonly with some brittlematerials. When it does occur, it ma
23、y begin during any stageof the more common erosion rate-time pattern.catastrophic wear, nrapidly occurring or accelerating sur-face damage, deterioration, or change of shape caused bywear to such a degree that the service life of a part isappreciably shortened or its function is destroyed.cavitating
24、 disk device (or apparatus), na flow cavitationtest device in which cavitating wakes are produced by holesin, or protuberances on, a disk rotating within a liquid-filledchamber. Erosion test specimens are attached flush with thesurface of the disk, at the location where the bubbles arepresumed to co
25、llapse.cavitating jet, na continuous liquid jet (sometimes sub-merged) in which cavitation is induced by the nozzle design,or sometimes by an obstruction placed in the center of theflow passage.cavitating wake, nSee flow cavitation.cavitation, nthe formation and subsequent collapse, within aliquid,
26、of cavities or bubbles that contain vapor or a mixtureof vapor and gas.DISCUSSIONCavitation originates from a local decrease in hydro-static pressure in the liquid, usually produced by motion of the liquid(see flow cavitation) or of a solid boundary (see vibratory cavitation).It is distinguished in
27、this way from boiling, which originates from anincrease in liquid temperature.DISCUSSIONThe term cavitation, by itself, should not be used todenote the damage or erosion of a solid surface that can be caused byit; this effect of cavitation is termed cavitation damage or cavitationerosion. To erode a
28、 solid surface, bubbles or cavities must collapse onor near that surface.cavitation cloud, na collection of a large number of cavita-tion bubbles. The bubbles in a cloud are small, typically lessthan 1 mm (0.04 in.) in cross section. A surface that is beingeroded by cavitation is usually obscured by
29、 a cavitationcloud.cavitation damage, nSee damage.cavitation erosion, nprogressive loss of original materialfrom a solid surface due to continued exposure to cavitation.cavitation erosion test, na procedure whereby the surface ofa solid is subjected to cavitation attack under specified, ormeasurable
30、, or at least repeatable conditions.DISCUSSIONSuch tests can be divided into two major classesdepending on whether flow cavitation or vibratory cavitation isgenerated.cavitation number, , na dimensionless number that mea-sures the tendency for cavitation to occur in a flowing streamof liquid, and th
31、at is computed from the equation: 5Po2 Pv!/12Vo2(1)where:Pv= vapor pressure,Po= static pressure in the stream in an undisturbed state,Vo= undisturbed stream velocity, and = liquid density.DISCUSSIONThe cavitation number and the net positive suction head(NPSH) are related by the equation:NPSH 5 11!Vo
32、2/2g (2)where g is the acceleration due to gravity.cavitation tunnel, na flow cavitation test facility in whichliquid is pumped through a pipe or tunnel, and cavitation isinduced in a test section by conducting the flow through aconstriction, or around an obstacle, or a combination ofthese.coefficie
33、nt of friction orf, nin tribology, the dimensionlessratio of the friction force (F) between two bodies to thenormal force (N) pressing these bodies together. (See alsostatic coefficient of friction and kinetic coefficient offriction.) 5 F/N! (3)collection efficiency, nin impingement erosion and part
34、icu-late flows, the cross-sectional area of undisturbed fluidcontaining particles that will all ultimately impinge on agiven solid surface, divided by the projected area of the solidsurface, where these two areas are perpendicular to theG40152direction of relative motion between the solid surface an
35、d theparticles in the undisturbed fluid.DISCUSSION“Undisturbed fluid” means fluid that is sufficientlyahead of the solid surface to be undisturbed by the flow around the solidsurface. For example, the particles could be carried in a stream of fluidmoving toward a solid surface that is stationary, or
36、 the solid surfacecould be moving through a suspension of particles. Not all of theparticles that move in the direction of the solid surface or lie in its pathwill impinge upon it, since some will be carried away in the fluid as itflows around the surface.DISCUSSIONA variety of terms having the same
37、 meaning can befound in the literature. These include “collision efficiency,” “captureefficiency,” “catchment efficiency,” “impaction ratio,” and others. Theterm “collection efficiency,” being perhaps the most widely used, ispreferred.continuous jet, nSee liquid jet.corrosive wear, nwear in which ch
38、emical or electrochemicalreaction with the environment is significant.cumulative erosion, nin cavitation and impingementerosion, the total amount of material lost from a solid surfaceduring all exposure periods since it was first exposed tocavitation or impingement as a newly-finished surface.(More
39、specific terms that may be used are cumulative massloss, cumulative volume loss,orcumulative mean depth oferosion. See also cumulative erosion-time curve.)DISCUSSIONUnless otherwise indicated by the context, it is impliedthat the conditions of cavitation or impingement have remained thesame througho
40、ut all exposure periods, with no intermediate refinishingof the surface.cumulative erosion rate, nthe cumulative erosion at aspecified point in an erosion test divided by the correspond-ing cumulative exposure duration; that is, the slope of a linefrom the origin to the specified point on the cumula
41、tiveerosion-time curve. (Synonym: average erosion rate)cumulative erosion-time curve, nin cavitation and im-pingement erosion, a plot of cumulative erosion versuscumulative exposure duration, usually determined by peri-odic interruption of the test and weighing of the specimen.This is the primary re
42、cord of an erosion test. Most othercharacteristics, such as the incubation period, maximumerosion rate, terminal erosion rate, and erosion rate-timecurve, are derived from it.cutting wear, nin solid impingement erosion, the erosivewear associated with the dissipation of kinetic energy ofimpact arisi
43、ng from the tangential component of the velocityof the impacting particles.DISCUSSIONSince erosion due to oblique particle impact inevitablyinvolves deformation wear as well as cutting wear, the magnitude of thecutting wear can be experimentally determined by conducting aseparate test at normal impa
44、ct to determine the deformation wear, andsubtracting that from the total wear at any angle of impact, where bothtests are conducted with the same normal component of impact velocityand both results are normalized to the mass of impacting particles. Seealso related terms deformation wear, ductile ero
45、sion behavior, andbrittle erosion behavior.damage, nin cavitation or impingement, any effect on a solidbody resulting from its exposure to these phenomena. Thismay include loss of material, surface deformation, or anyother changes in microstructure, properties, or appearance.DISCUSSIONThis term as h
46、ere defined should normally be used withthe appropriate modifier, for example, “cavitation damage,” “liquidimpingement damage,” “single-impact damage,” and so forth.debris, nin tribology, particles that have become detached ina wear or erosion process.deceleration period, nin cavitation or liquid im
47、pingementerosion, the stage following the acceleration period or themaximum rate period (if any) during which the erosion ratehas an overall decreasing trend although fluctuations may besuperimposed on it. (See also erosion rate-time pattern.)deformation wear, nin solid impingement erosion, theerosi
48、ve wear of a material associated with the dissipation ofkinetic energy of impact arising from the normal componentof the velocity of the impacting particles. It is therefore thesole component of wear for particles impacting at a 90angle of attack.DISCUSSIONThis term is used for the erosion of brittl
49、e materials,even though plastic deformation is lacking. See also related termsbrittle erosion behavior, ductile erosion behavior, and cutting wear.distributed impact test, nin impingement erosion testing,anapparatus or method that produces a spatial distribution ofimpacts by liquid or solid bodies over an exposed surface ofa specimen.DISCUSSIONExamples of such tests are those employing liquidsprays or simulated rainfields. If the impacts are distributed uniformlyover the surface, the term “uniformly distributed
