ASTM G40-02

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Designation:G40–02
Standard Terminology Relating to
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Wear and Erosion
ThisstandardisissuedunderthefixeddesignationG40;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope is affected by the simultaneous action of the other and, in
many cases, is thereby accelerated.
1.1 The terms and their definitions given herein represent
abrasivity, n—the ability of a material or substance to cause
terminologyrelatingtowearanderosionofsolidbodiesdueto
abrasive wear.
mechanical interactions such as occur with cavitation, im-
absolute impact velocity— See impact velocity.
pingement by liquid jets or drops or by solid particles, or
acceleration period, n— in cavitation and liquid impingement
relative motion against contacting solid surfaces or fluids.This
erosion, the stage following the incubation period during
scope interfaces with but generally excludes those processes
which the erosion rate increases from near zero to a
where material loss is wholly or principally due to chemical
maximum value. (See also erosion rate-time pattern.)
action and other related technical fields as, for instance,
accumulation period, n— in cavitation and liquid impinge-
lubrication.
ment erosion, a less-preferred term for acceleration period.
1.2 This terminology is not exhaustive; the absence of any
adhesive wear, n—wear due to localized bonding between
particular term from this collection does not necessarily imply
contacting solid surfaces leading to material transfer be-
that its use within this scope is discouraged. However, the
tween the two surfaces or loss from either surface.
termsgivenhereinaretherecommendedtermsfortheconcepts
angle of attack, n— in impingement erosion, the angle
they represent unless otherwise noted.
between the direction of motion of an impinging liquid or
1.3 Certain general terms and definitions may be restricted
solid particle and the tangent to the surface at the point of
and interpreted, if necessary, to make them particularly appli-
impact.
cable to the scope as defined herein.
angle of incidence, n— in impingement erosion, the angle
1.4 The purpose of this terminology is to encourage unifor-
between the direction of motion of an impinging liquid or
mity and accuracy in the description of test methods and
solid particle and the normal to the surface at the point of
devices and in the reporting of test results in relation to wear
impact.
and erosion.
apparent area of contact, n—in tribology, the area of contact
NOTE 1—All terms are listed alphabetically. When a subsidiary term is
betweentwosolidsurfacesdefinedbytheboundariesoftheir
defined in conjunction with the definition of a more generic term, an
macroscopic interface. (Contrast with real area of contact.)
alphabetically-listed cross-reference is provided.
asperity, n—in tribology, a protuberance in the small-scale
topographical irregularities of a solid surface.
2. Referenced Documents
attenuation period, n— in cavitation and liquid impingement
2.1 ASTM Standards:
erosion, a less-preferred term for deceleration period.
C242 Terminology of Ceramic Whitewares and Related
2 average erosion rate, n—alesspreferredtermfor cumulative
Products
erosion rate.
3. Terminology Beilby layer, n—an altered surface layer of supposedly amor-
phousmaterialformedonacrystallinesolidduringmechani-
abrasive wear, n—wear due to hard particles or hard protu-
cal polishing, whose existence was proposed in Sir George
berances forced against and moving along a solid surface.
Beilby’s writings. The existence of such a layer is not
abrasion-corrosion, n—a synergistic process involving both
supported by recent research, and the use of this term is
abrasivewearandcorrosioninwhicheachoftheseprocesses
therefore considered archaic and is strongly discouraged.
break-in, n—See run-in.
1 break in, v—See run in.
This terminology is under the jurisdiction of ASTM Committee G02 on Wear
and Erosion and is the direct responsibility of Subcommittee G02.91 on Terminol- brinelling, n—damagetoasolidbearingsurfacecharacterized
ogy.
by one or more plastically formed indentations caused by
Current edition approved Oct. 10, 2002. Published December 2002. Originally
static or impulsive overloads, especially as found in rolling
approved in 1973. Last previous edition approved in 2001 as G40–01.
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contact bearings. (See also false brinelling.)
Annual Book of ASTM Standards, Vol 15.02.
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