1、Designation: G40 12Standard 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.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 bothabras
8、ive wear and corrosion in which each of these processesis affected by the simultaneous action of 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 cavitati
9、on and liquid impingementerosion, the stage following the incubation period duringwhich the erosion 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
10、.adhesive wear, nwear due to localized bonding betweencontacting solid surfaces leading to material 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 tangen
11、t to the surface at the point of impact.angle of incidence, nin impingement erosion, the anglebetween 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 surf
12、aces defined by the boundaries of theirmacroscopic interface. (Contrast with real area of contact.)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 dec
13、eleration period.average erosion rate, na less preferred term for cumulativeerosion rate. (See also interval erosion rate.)Beilby 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 GeorgeB
14、eilbys writings. The existence of such a layer is notsupported by recent research, and the use of this term istherefore considered archaic and is strongly discouraged.break-in, nSee run-in.break in, vSee run in.brinelling, ndamage to a solid bearing surface characterizedby one or more plastically fo
15、rmed indentations caused by1This 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 May 1, 2012. Published August 2012. Originallyapproved in 1973. Last previous edition appro
16、ved in 2010 as G4010b. DOI:10.1520/G0040-12.2For 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.1Copyright ASTM I
17、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.static or impulsive overloads, especially as found in rollingcontact bearings. (See also false brinelling.)brittle erosion behavior, nerosion behavior having charac-teristic properties that can be assoc
18、iated with brittle fractureof the exposed surface; that is, little or no plastic flow occurs,but cracks form that eventually intersect to create erosionfragments. (See also ductile erosion behavior.)DISCUSSIONIn solid impingement an easily observable aspect oferosion helps to distinguish brittle fro
19、m 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 contrast to approximately 25 for ductile erosion behavior.carrier fluid, nin impingement or slurry erosion, fluidmedium that tra
20、nsports impinging solid or liquid particlesand that gives the particles their momentum relative to thesolid surface on which they are impinging.catastrophic period, nin cavitation or liquid impingementerosion, a stage during which the erosion rate increases sodrastically that continued exposure thre
21、atens or causes grossdisintegration of the exposed surface. This stage is notinevitable; it is observed most commonly with some brittlematerials. When it does occur, it may begin during any stageof the more common erosion rate-time pattern.catastrophic wear, nrapidly occurring or accelerating sur-fa
22、ce 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 disk device (or apparatus), na flow cavitationtest device in which cavitating wakes are produced by holesin, or protuberances on
23、, 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 collapse.cavitating jet, na continuous liquid jet (sometimes sub-merged) in which cavitation is induced by the nozzle design,or som
24、etimes by an obstruction placed in the center of theflow passage.cavitating wake, nSee flow cavitation.cavitation, nthe formation and subsequent collapse, within aliquid, of cavities or bubbles that contain vapor or a mixtureof vapor and gas.DISCUSSIONCavitation originates from a local decrease in h
25、ydro-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 this way from boiling, which originates from anincrease in liquid temperature.DISCUSSIONThe term cavitation, by itself, should no
26、t 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 solid surface, bubbles or cavities must collapse onor near that surface.cavitation cloud, na collection of a large number of cav
27、ita-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 a cavitationcloud.cavitation damage, n See damage.cavitation erosion, nprogressive loss of original materialfrom a solid surface
28、 due to continued exposure to cavitation.cavitation erosion test, na procedure whereby the surface ofa solid is subjected to cavitation attack under specified, ormeasurable, or at least repeatable conditions.DISCUSSIONSuch tests can be divided into two major classesdepending on whether flow cavitati
29、on or vibratory cavitation isgenerated.cavitation number, s, na dimensionless number that mea-sures the tendency for cavitation to occur in a flowing streamof liquid, and that is computed from the equation:s5SPo2 Pv!/12rVo2(1)where:Pv= vapor pressure,Po= static pressure in the stream in an undisturb
30、ed state,Vo= undisturbed stream velocity, andr = liquid density.DISCUSSIONThe cavitation number and the net positive suction head(NPSH) are related by the equation:NPSH 5 s11!Vo2/2g (2)where g is the acceleration due to gravity.cavitation tunnel, na flow cavitation test facility in whichliquid is pu
31、mped 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.coefficient of friction orf, nin tribology, the dimension-less ratio of the friction force (F) between two bodies to thenormal force
32、 (N) pressing these bodies together. (See alsostatic coefficient of friction and kinetic coefficient offriction.) 5 F/N! (3)collection efficiency, nin impingement erosion and particu-late flows, the cross-sectional area of undisturbed fluidcontaining particles that will all ultimately impinge on agi
33、ven solid surface, divided by the projected area of the solidsurface, where these two areas are perpendicular to thedirection of relative motion between the solid surface and theparticles in the undisturbed fluid.DISCUSSION“Undisturbed fluid” means fluid that is sufficientlyahead of the solid surfac
34、e 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 the solid surfacecould be moving through a suspension of particles. Not all of theparticles that move in the direction of the
35、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 meaning can befound in the literature. These include “collision efficiency,” “ captureefficiency,” “catchment efficiency,” “ i
36、mpaction ratio,” and others. Theterm “collection efficiency,” being perhaps the most widely used, ispreferred.continuous jet, nSee liquid jet.G40122corrosive wear, nwear in which chemical or electrochemicalreaction with the environment is significant.cumulative erosion, nin cavitation and impingemen
37、t ero-sion, 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 specific terms that may be used are cumulative massloss, cumulative volume loss,orcumulative mean depth oferosion. Se
38、e also cumulative erosion-time curve.)DISCUSSIONUnless otherwise indicated by the context, it is impliedthat the conditions of cavitation or impingement have remained thesame throughout all exposure periods, with no intermediate refinishingof the surface.cumulative erosion rate, nthe cumulative eros
39、ion 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 cumulativeerosion-time curve. ( Synonym: average erosion rate)cumulative erosion-time curve, nin cavitation and im-pingemen
40、t 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 record of an erosion test. Most othercharacteristics, such as the incubation period, maximumerosion rate, terminal ero
41、sion 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 arising from the tangential component of the velocityof the impacting particles.DISCUSSIONSince erosion due to oblique pa
42、rticle impact inevitablyinvolves deformation wear as well as cutting wear, the magnitude of thecutting wear can be experimentally determined by conducting aseparate test at normal impact to determine the deformation wear, andsubtracting that from the total wear at any angle of impact, where bothtest
43、s 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 erosion behavior, andbrittle erosion behavior.damage, nin cavitation or impingement, any effect on a solidbody resultin
44、g from its exposure to these phenomena. Thismay include loss of material, surface deformation, or anyother changes in microstructure, properties, or appearance.DISCUSSIONThis term as here defined should normally be used withthe appropriate modifier, for example, “cavitation damage,” “liquidimpingeme
45、nt 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 impingementerosion, the stage following the acceleration period or themaximum rate period (if any) during which the er
46、osion ratehas an overall decreasing trend although fluctuations may besuperimposed on it. (See also erosion rate-time pattern.)deformation wear, nin solid impingement erosion, theerosive wear of a material associated with the dissipation ofkinetic energy of impact arising from the normal componentof
47、 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 brittle materials,even though plastic deformation is lacking. See also related termsbrittle erosion behavior, ductile eros
48、ion behavior, and cutting wear.distributed impact test, nin impingement erosion testing,an apparatus 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
49、rainfields. If the impacts are distributed uniformlyover the surface, the term “uniformly distributed impact test” may beused. (Contrast with repetitive impact erosion test.)drop, liquid, nsee liquid drop.drop size, nthe diameter of a liquid drop if it is approxi-mately spherical; otherwise, the approximate shape andappropriate dimensions must be described.DISCUSSIONIn a spray or rainfall, there will normally be a spectrumof drop sizes, which can be presented by distribution curves orhistograms, showing either number
