ASTM G73-10(2021)
(Test Method)Standard Test Method for Liquid Impingement Erosion Using Rotating Apparatus
Standard Test Method for Liquid Impingement Erosion Using Rotating Apparatus
SIGNIFICANCE AND USE
5.1 Erosion Environments—This test method may be used for evaluating the erosion resistance of materials for service environments where solid surfaces are subjected to repeated impacts by liquid drops or jets. Occasionally, liquid impact tests have also been used to evaluate materials exposed to a cavitating liquid environment. The test method is not intended nor applicable for evaluating or predicting the resistance of materials against erosion due to solid particle impingement, due to “impingement corrosion” in bubbly flows, due to liquids or slurries “washing” over a surface, or due to continuous high-velocity liquid jets aimed at a surface. For background on various forms of erosion and erosion tests, see Refs (1) through (2).4 Ref (3) is an excellent comprehensive treatise.
5.2 Discussion of Erosion Resistance—Liquid impingement erosion and cavitation erosion are, broadly speaking, similar processes and the relative resistance of materials to them is similar. In both, the damage is associated with repeated, small-scale, high-intensity pressure pulses acting on the solid surface. The precise failure mechanisms in the solid have been shown to differ depending on the material, and on the detailed nature, scale, and intensity of the fluid-solid interactions (Note 1). Thus, “erosion resistance” should not be regarded as one precisely-definable property of a material, but rather as a complex of properties whose relative importance may differ depending on the variables just mentioned. (It has not yet been possible to successfully correlate erosion resistance with any independently measurable material property.) For these reasons, the consistency between relative erosion resistance as measured in different facilities or under different conditions is not very good. Differences between two materials of say 20 % or less are probably not significant: another test might well show them ranked in reverse order. For bulk materials such as metals and structural plastics, the...
SCOPE
1.1 This test method covers tests in which solid specimens are eroded or otherwise damaged by repeated discrete impacts of liquid drops or jets. Among the collateral forms of damage considered are degradation of optical properties of window materials, and penetration, separation, or destruction of coatings. The objective of the tests may be to determine the resistance to erosion or other damage of the materials or coatings under test, or to investigate the damage mechanisms and the effect of test variables. Because of the specialized nature of these tests and the desire in many cases to simulate to some degree the expected service environment, the specification of a standard apparatus is not deemed practicable. This test method gives guidance in setting up a test, and specifies test and analysis procedures and reporting requirements that can be followed even with quite widely differing materials, test facilities, and test conditions. It also provides a standardized scale of erosion resistance numbers applicable to metals and other structural materials. It serves, to some degree, as a tutorial on liquid impingement erosion.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: G73 − 10 (Reapproved 2021)
Standard Test Method for
Liquid Impingement Erosion Using Rotating Apparatus
ThisstandardisissuedunderthefixeddesignationG73;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method covers tests in which solid specimens 2.1 ASTM Standards:
are eroded or otherwise damaged by repeated discrete impacts D1003Test Method for Haze and Luminous Transmittance
of liquid drops or jets. Among the collateral forms of damage of Transparent Plastics
considered are degradation of optical properties of window E92Test Methods for Vickers Hardness and Knoop Hard-
materials, and penetration, separation, or destruction of coat- ness of Metallic Materials
ings. The objective of the tests may be to determine the E140Hardness Conversion Tables for Metals Relationship
resistance to erosion or other damage of the materials or Among Brinell Hardness, Vickers Hardness, Rockwell
coatings under test, or to investigate the damage mechanisms Hardness, Superficial Hardness, Knoop Hardness, Sclero-
and the effect of test variables. Because of the specialized scope Hardness, and Leeb Hardness
natureofthesetestsandthedesireinmanycasestosimulateto E177Practice for Use of the Terms Precision and Bias in
some degree the expected service environment, the specifica- ASTM Test Methods
tionofastandardapparatusisnotdeemedpracticable.Thistest E179Guide for Selection of Geometric Conditions for
method gives guidance in setting up a test, and specifies test Measurement of Reflection and Transmission Properties
andanalysisproceduresandreportingrequirementsthatcanbe of Materials
followed even with quite widely differing materials, test G1Practice for Preparing, Cleaning, and Evaluating Corro-
facilities, and test conditions. It also provides a standardized sion Test Specimens
scale of erosion resistance numbers applicable to metals and G32Test Method for Cavitation Erosion Using Vibratory
other structural materials. It serves, to some degree, as a Apparatus
tutorial on liquid impingement erosion. G40Terminology Relating to Wear and Erosion
G134Test Method for Erosion of Solid Materials by Cavi-
1.2 The values stated in SI units are to be regarded as
tating Liquid Jet
standard. The values given in parentheses after SI units are
2.2 Military Standards:
providedforinformationonlyandarenotconsideredstandard.
MIL-C-83231Coatings, Polyurethane, Rain Erosion Resis-
1.3 This standard does not purport to address all of the
tance for Exterior Aircraft and Missile Plastic Parts
safety concerns, if any, associated with its use. It is the
MIL-P-8184Plastic Sheet, Acrylic, Modified
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to use.
3.1 See Terminology G40 for definitions of terms that are
1.4 This international standard was developed in accor-
notdefinedbelowineither3.2or3.3.Definitionsappearin3.2
dance with internationally recognized principles on standard-
that are taken from Terminology G40 for important terms
ization established in the Decision on Principles for the
related to the title, Scope, or Summary of this test method.
Development of International Standards, Guides and Recom-
Definitions of Terms Specific to this Test Method are given in
mendations issued by the World Trade Organization Technical
3.3 that are not in Terminology G40.
Barriers to Trade (TBT) Committee.
1 2
This test method is under the jurisdiction of ASTM Committee G02 on Wear For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and Erosion and is the direct responsibility of Subcommittee G02.10 on Erosion by contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Solids and Liquids. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2021. Published December 2021. Originally the ASTM website.
approvedin1982.Lastpreviouseditionapprovedin2017asG73–10(2017).DOI: Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,
10.1520/G0073-10R21. Philadelphia, PA 19111-5094, http://quicksearch.dla.mil.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G73 − 10 (2021)
3.2 Definitions: a specified reference material similarly tested and similarly
3.2.1 AlldefinitionslistedbelowarequotedfromTerminol- analyzed. (See also normalized erosion resistance.)
ogy G40–05 (some modified).
3.3 Definitions of Terms Specific to This Standard:
3.2.2 cumulative erosion-time curve, n—in cavitation and
3.3.1 apparatus severity factor, F—an empirical factor that
impingement erosion, a plot of cumulative erosion versus
accounts for the systematic differences between rationalized
cumulative exposure duration, usually determined by periodic
erosionrates(orrationalizedincubationperiods)asdetermined
interruption of the test and weighing of the specimen. This is
forthesamematerialandimpactvelocityindifferentfacilities.
the primary record of an erosion test. Most other
It reflects variations in test conditions not accounted for by the
characteristics, such as the incubation period, maximum ero-
data reduction procedures of this test method.
sionrate,terminalerosionrate,anderosionrate-timecurve,are
derived from it.
3.3.2 erosion resistance number, NER—the normalized ero-
sion resistance of a test material relative to a standardized
3.2.3 damage, n—in cavitation or impingement, any effect
scale, calculated from test results with one or more designated
on a solid body resulting from its exposure to these phenom-
reference materials as described in this test method. See also
ena.This may include loss of material, surface deformation, or
reference erosion resistance (3.3.12).
anyotherchangesinmicrostructure,properties,orappearance.
3.2.3.1 Discussion—This term as here defined should nor-
3.3.3 exposed surface (or area)—that surface (or area) on
mally be used with the appropriate modifier, for example,
the specimen nominally subjected to liquid impingement.
“cavitation damage,” “liquid impingement damage,” “single-
(1)For“distributedimpacttests,”itisgenerallytobetaken
impact damage,” and so forth.
astheprojectedareaoftheexposedsurfaceofthespecimenon
3.2.4 incubation period, n—in cavitation and impingement
a plane perpendicular to the direction of impingement.
erosion, the initial stage of the erosion rate-time pattern during
However, if a plane specimen surface is deliberately oriented
which the erosion rate is zero or negligible compared to later
soastoobtainimpingementatanobliqueangle,thentheactual
stages.
plane area is used.
3.2.4.1 Discussion—The incubation period is usually
(2)For “repetitive impact tests,” it is to be taken as the
thought to represent the accumulation of plastic deformation
projected area of the impinging liquid bodies on the specimen,
and internal stresses under the surface that precedes significant
the projection being taken in the direction of relative motion.
material loss. There is no exact measure of the duration of the
3.3.3.1 Discussion—In practice, it is usually found that the
incubationperiod.Seerelatedterm, nominal incubation period
damaged area in repetitive impact tests is greater than the
in 3.3.9.
exposed area as defined above, but the above definition is
3.2.5 liquid impingement erosion, n—progressive loss of
adopted not only for simplicity but also for consistency
original material from a solid surface due to continued expo-
between some of the other calculations for distributed and
sure to impacts by liquid drops or jets.
repetitive tests.
−1
3.2.6 maximum erosion rate, n—in cavitation and liquid
3.3.4 impingement rate, U [LT ]—the volume of liquid
i
impingement,themaximuminstantaneouserosionrateinatest
impinging per unit time on a unit area of exposed surface; for
that exhibits such a maximum followed by decreasing erosion
a plane target surface it is given by ψ V cos θ.
rates. (See also erosion rate–time pattern.)
3.3.5 incubation impingement, H [L]—the mean cumula-
3.2.6.1 Discussion—Occurrence of such a maximum is
tive impingement corresponding to the nominal incubation
typical of many cavitation and liquid impingement tests. In
period; hence, impingement rate times nominal incubation
some instances it occurs as an instantaneous maximum, in
time.
others as a steady-state maximum which persists for some
time.
3.3.6 incubation resistance number, NOR—the normalized
incubation resistance of a test material relative to a standard-
3.2.7 normalizederosionresistance,N,n—ameasureofthe
e
ized scale, calculated from test results with one or more
erosion resistance of a test material relative to that of a
designatedreferencematerialsasdescribedinthistestmethod.
specifiedreferencematerial,calculatedbydividingthevolume
See also reference incubation resistance (3.3.13).
loss rate of the reference material by that of the test material
when both are similarly tested and similarly analyzed. By
3.3.7 incubation specific impacts, N —same as rationalized
“similarlyanalyzed,”itismeantthatthetwoerosionratesmust
incubation period.
be determined for corresponding portions of the erosion
3.3.8 mean cumulative impingement, H[L]—thecumulative
rate-timepattern;forinstance,themaximumerosionrateorthe
volume of liquid impinged per unit area of exposed surface;
terminal erosion rate.
impingement rate times exposure time.
3.2.7.1 Discussion—Arecommended complete wording has
the form, “The normalized erosion resistance of (test material)
3.3.9 nominal incubation period, t —the intercept on the
relative to (reference material) based on (criterion of data
time or exposure axis of the straight-line extension of the
analysis) is (numerical value).”
maximum-slope portion of the cumulative erosion-time curve;
3.2.8 normalized incubation resistance, N , n—in cavitation while this is not a true measure of the incubation stage, it
and liquid impingement erosion,thenominalincubationperiod serves to locate the maximum erosion rate line on the cumu-
of a test material, divided by the nominal incubation period of lative erosion versus exposure coordinates.
G73 − 10 (2021)
3.3.10 rationalized erosion rate, R —volume of material
S = normalizedincubationresistance(relativetoaspeci-
e
lostperunitvolumeofliquidimpinged,bothcalculatedforthe
fied reference material),
same area.
S = reference incubation resistance,
or
t = exposure time, s,
3.3.11 rationalized incubation period, N —the duration of
t = nominal incubation time, s,
the nominal incubation period expressed in dimensionless
U = linear erosion rate (dY/dt), m/s= Q /A,
e e
terms as the number of specific impacts; hence, the specific
U = impingement rate (dH/dt), m/s,
i
impact frequency times nominal incubation time. (Also re-
U = rainfall rate, m/s,
r
ferred to as incubation specific impacts.)
U = terminal velocity of drops in falling rainfield, m/s,
t
3.3.12 reference erosion resistance, S —a normalized ero- V = impact velocity of drop or jet relative to specimen,
er
sion resistance, based on interlaboratory test results, assigned m/s,
V = component of impact velocity normal to specimen
to a specified reference material in this test method so as to
n
surface, m/s,
constitute a benchmark in the “erosion resistance number”
Y = mean depth of erosion, m,
scale. The value of unity is assigned to 316 stainless steel of
θ = angle of incidence—the angle between the direction
hardness 155 to 170 HV.
of impacting drops and the normal to the solid
3.3.13 reference incubation resistance, S —a normalized
or
surface at point of impact,
incubation resistance, based on interlaboratory test results,
ψ = volume concentration of liquid in rainfield or in
assigned to a specific reference material in this test method so
space swept through by specimen, and
as to constitute a benchmark in the “incubation resistance
Ω = rotational speed of specimens, rev/s.
number” scale. The value of unity is assigned to 316 stainless
3.5 Except in equations where different units are expressly
steel of hardness 155 to 170 HV.
specified,theuseofSIunitslistedin3.4,oranyother coherent
3.3.14 specific impacts, N—the number of impact stress
system of units, will make equations correct without the need
cycles of damaging magnitude experienced by a typical point
of additional numerical factors.When referring to quantities in
on the exposed surface, or an approximation thereof as
text, tables, or figures, suitable multiples or submultiples of
estimated on the basis of simplified assumptions as described
these units may, of course, be used.
in this test method. (This concept has sometimes been termed
“impacts per site.”) 4. Summary of Test Method
−1
3.3.15 specific impact frequency, f [T ]—the number of
4.1 Liquid impingement tests are usually, but not always,
i
specific impacts experienced per unit time, given by (a/b) U. conducted by attaching specimens to a rotating disk or arm,
i
suchthatintheircircularpaththeyrepeatedlypassthroughand
3.3.16 volume concentration,ψ—the ratio of the volume of
impactagainstliquidspraysorjets(Sections6and7).Standard
liquid to the total volume in the path traversed or swept out by
reference materials (Section 8) should be used to calibrate the
the exposed area of the specimen.
apparatus and included in all test programs.
3.3.17 volume mean diameter [L]—in a population of drops
4.2 Data analysis begins by establishing a cumulative
of different sizes, the diameter of a sphere whose volume
erosion-time curve from measurements of mass loss (or other
equalsthetotalvolumeofalldropsdividedbythetotalnumber
damage manifestation) periodically during the tests (Section
of drops.
9). These curves are then characterized by specified attributes
3.4 Symbols:
such as the nominal incubation time and the maximum erosion
2 rate (Section 10).
A = exposed area of specimen, m ,
a = projected area of impinging drop or jet, m , 4.3 For comparative materials evaluations, the results are
b = volume of impinging drop or jet, m ,
normalized (Section 10) with respect to the standard reference
d = diameter of impinging drop or jet, m,
materials included in the test program.Astandardized scale of
F = apparatus severity factor for incubation,
“erosion resistance numbers” is provided for stru
...
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