ASTM G76-18 Red-Line

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what
changes have been made to the previous version. Because

it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: G76 − 13 G76 − 18
Standard Test Method for

Conducting Erosion Tests by Solid Particle Impingement
Using Gas Jets1
This standard is issued under the fixed designation G76; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of material loss by gas-entrained solid particle impingement erosion with
jetnozzle type erosion equipment. This test method may be used in the laboratory to measure the solid particle erosion of different
materials and has been used as a screening test for ranking solid particle erosion rates of materials in simulated service
environments (1, 2).2 Actual erosion service involves particle sizes, velocities, attack angles, environments, and so forth, that will
vary over a wide range (3-5). Hence, any single laboratory test may not be sufficient to evaluate expected service performance.
This test method describes one well characterized procedure for solid particle impingement erosion measurement for which
interlaboratory test results are available.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard (exceptions below).
1.2.1 Exceptions: Table 1 uses HRB hardness. Footnote 7 and 11.2 use abrasive grit designations.
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 safety, health, and healthenvironmental 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.
2. Referenced Documents
2.1 ASTM Standards:3
E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or
Process
G40 Terminology Relating to Wear and Erosion
2.2 American National Standard:
ANSI B74.10 Grading of Abrasive Microgrits4
1
This test method is under the jurisdiction of ASTM Committee G02 on Wear and Erosion and is the direct responsibility of Subcommittee G02.10 on Erosion by Solids
and Liquids.
Current edition approved July 1, 2013Oct. 1, 2018. Published July 2013November 2018. Originally approved in 1983. Last previous edition approved in 20072013 as
G76G76 – 13.–07. DOI: 10.1520/G0076-13.10.1520/G0076-18.
2
The boldface numbers in parentheses refer to a list of references at the end of this standard.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
4
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.
TABLE 1 Characteristics of Type 1020 Steel Reference Material

Annealed 900 s at 760°C, air cooled.
Hardness: HRB = 70 ± 2.
Chemical Composition:
C = 0.20 ± 0.01 wt %
Mn = 0.45 ± 0.10
S = 0.03 ± 0.01
Si = 0.1± 0.05
P = 0.01 ± 0.01
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
Copyright by ASTM Int'l (all rights reserved); Tue Aug 25 08:53:01 EDT 2020 1
Downloaded/printed by
OSCAR BELALCAZAR (VAN DAMME HELICOPTERS INC) pursuant to License Agreement. No further reproductions authorized.
G76 − 18
where:
a = gas jet nozzle,
b = nozzle length,
c = mixing chamber,
d = abrasive hopper,
e = gas source,
f = test specimen,
g = nozzle-to-specimen distance, and
θ = impingement angle.
FIG. 1 Schematic Drawing of Solid Particle Erosion Equipmentof Test Rig
3. Terminology
3.1 Definitions:
3.1.1 erosion—progressive loss of original material from a solid surface due to mechanical interaction between that surface and
a fluid, a multicomponent fluid, or impinging liquid or solid particles.
3.1.2 impingement—a process resulting in a continuing succession of impacts between (liquid or solid) particles and a solid
surface.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 erosion value—the volume loss of specimen material divided by the total mass of abrasive particles that impacted the
specimen (mm3·g−1).
3.2.2 Normalized Erosion Rate—erosion value (mm3·g−1) of specimen material divided by erosion value (mm3·g−1) of reference
material.
4. Summary of Test Method

4.1 This test method utilizes a repeated impact erosion approach involving a small nozzle delivering a stream of gas containing
abrasive particles which impacts the surface of a test specimen. A standard set of test conditions is described. However, deviations
from some of the standard conditions are permitted if described thoroughly. This allows for laboratory scale erosion measurements
under a range of conditions. Test methods are described for preparing the specimens, conducting the erosion exposure, and
reporting the results.
5. Significance and Use

5.1 The significance of this test method in any overall measurements program to assess the erosion behavior of materials will
depend on many factors concerning the conditions of service applications. The users of this test method should determine the
degree of correlation of the results obtained with those from field performance or results using other test systems and methods.
This test method may be used to rank the erosion resistance of materials under the specified conditions of testing.
6. Apparatus
6.1 The apparatus is capable of eroding material from a test specimen under well controlled exposure conditions. A schematic
drawing of the exit nozzle and the particle-gas supply system is shown in Fig. 1. Deviations from this design are permitted;
however, adequate system characterization and control of critical parameters are required. Deviations in nozzle design and
dimensions must be documented. Nozzle length to diameter ratio should be 25:1 or greater in order to achieve an acceptable
particle velocity distribution in the stream. The recommended nozzle5 consists of a tube about 1.5 mm inner diameter, 50 mm long,
manufactured from an erosion resistant material such as WC, A12O3, and so forth. Erosion of the nozzle during service shall be
monitored and shall not exceed 10 % increase in the initial diameter.
5
The sole source of supply of the recommended nozzle (tungsten carbide) known to the committee at this time is Kennametal Inc., 1600 Technology Way, PO Box 231,
Latrobe, PA 15650-0231. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful
consideration at a meeting of the responsible technical committee,1 which you may attend.
G76 − 18
FIG. 2 Microstructure of 1020 Steel Reference Material

ASTM Grain Size 9
6.2 Necessary features of the apparatus shall include a means of controlling and adjusting the particle impact velocity, particle
flux, and the specimen location and orientation relative to the impinging stream.stream (impingement angle).
6.3 Various means can be provided for introducing particles into the gas stream, including a vibrator-controlled hopper or a
screw-feed system. It is required that the system provide a uniform particle feed and that it be adjustable to accommodate desired
particle flow values.
6.4 A method to measure the particle velocity shall be available for use with the erosion equipment (6-9). Examples of accepted
methods are high-speed photography (7), rotating double-disk (6),(8), and laser velocimeter (9). Particle velocity shall be measured
at the location to be occupied by the specimen and under the conditions of the test.
7. Test Materials and Sampling

7.1 This test method can be used over a range of specimen sizes and configurations. One convenient specimen configuration
is a rectangular strip approximately 10 by 30 by 2 mm thick. Larger specimens and other shapes can be used where necessary, but
must be documented.
7.2 The abrasive material to be used shall be uniform in essential characteristics such as particle size, moisture, chemical
composition, and so forth.
7.3 Sampling of material for the purpose of obtaining representative test specimens shall be done in accordance with acceptable
statistical practice. Practice E122 shall be consulted.
8. Calibration of Apparatus
8.1 Specimens fabricated from Type 1020 steel (see Table 1 and Fig. 2) equivalent to that used in the interlaboratory test series6
shall be tested periodically using specified (see Section 9) 50 µm A12O3 particles to verify the satisfactory performance of the
apparatus. It is recommended that performance be verified using this reference material every 50 tests during a measurement series,
and also at the beginning of each new test series whenever the apparatus has been idle for some time. The recommended
composition, heat treatment, and hardness range for this steel are listed in Table 1. The use of a steel of different composition may
lead to different erosion results. A photomicrograph of the specified A12O3 particles is shown in Fig. 3. The range of erosion results
to be expected for this steel under the standard test conditions specified in Section 9 is shown in Table 2 and is based on
interlaboratory test results.6
8.2 Calibration at standard test conditions is recommended even if the apparatus is operated at other test conditions.
8.3 In any test program the particle velocity and particle feed rate shall be measured at frequent intervals, typically every ten
tests, to ensure constancy of conditions.
6
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:G02-1003.
G76 − 18
FIG. 3 Photomicrograph of 50 µm A12O3 Particles Used in Interlaboratory Testing
9. Standard Test Conditions

9.1 This test method defines the following standard conditions.
9.1.1 The nozzle tube shall be 1.5 mm 6 0.075 mm inner diameter at least 50 mm long.
9.1.2 The test gas shall be nominally dry air. The test report shall indicate the amount of water present in the test gas, at what
pressure, and how the measurement was conducted.
NOTE 1—In the interlaboratory testing, one laboratory utilized cylinder-type compressed air having a water content amount described as “-50°C dew
point” by the manufacturer. Whatever gas source is used in testing, a comparable level of dryness to that is recommended.
9.1.3 The abrasive particles shall be nominal 50-µm angular A12O3,7 equivalent to those used in the interlaboratory test series
(see Fig. 3). Abrasive shall be used only once.
NOTE 2—Typical size distribution (determined by sedimentation): 100 % between 20 to 83 µm, 50 % between 42 to 57 µm, 50 % coarser than 48 µm.
9.1.4 The abrasive particle velocity shall be 30 6 2 m·s−1, measured at the specimen location. At this velocity the gas flow rate
will be approximately 0.13 L/s and the system pressure will be approximately 140 kPa although the pressure will depend on the
specific system design.
9.1.5 The test time shall be 600 s to achieve steady state conditions. Longer times are permissible so long as the final erosion
crater is no deeper than 1 mm.
9.1.6 The angle between the nozzle axis and the specimen surface shall be 90 6 2°.
9.1.7 The test temperature shall be the normal ambient value (typically between 18°C to 28°C).
9.1.8 The particle feed rate shall be 0.033 6 0.008 g/s. This corresponds to a particle flux at the specimen surface of about 2
mg·mm−2·s−1 under standard conditions. Particle flux determination requires measurement of the eroded area on the specimen and
is subject to considerable error. A measured width and depth profile of an erosion crater produced using stated conditions is shown
in Fig. 4 and indicates a typical eroded width/depth relation.
9.1.9 The distance from specimen surface to nozzle end shall be 10 6 1 mm.
10. Optional Test Conditions
10.1 When test conditions or materials other than those given in Section 9 are used, reference to this test method shall clearly
specify all test conditions and materials. It should be noted that other conditions, for example, larger particle velocities, may
adversely affect measurement precision.
7
The sole source of supply of the aluminum oxide particles—obtained as grade 240-grit alundum powder— knownaluminum oxide powder—known to the committee
at this time is Norton Co., 1 New Bond St, Worcester, MA 01606. If you are aware of alternative suppliers, please provide this information to ASTM International
Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee,1 which you may attend.
G76 − 18
FIG. 4 Example of Erosion Crater Profile for 1020 Steel Eroded at 70 m/s Particle Velocity Using Standard Conditions Otherwise
11. Test Procedure

11.1 Establish and measure the particle velocity and particle flow specified. Adjust equipment controls to obtain proper velocity
and flow conditions before inserting test specimens. Particle flow rate values are determined by collecting (see Note 3) and
subsequently weighing the abrasive exiting from the nozzle for a measured time period.
NOTE 3—Particles may be collected by directing the flow from the nozzle into a large vented container. Care must be taken to avoid causing any
significant back pressure on the nozzle as this will disturb the system flow conditions.
11.2 Prepare the specimen surface if required to achieve uniformity and adequate finish. Grinding through a series of abrasive
papers to 400 grit is usually adequate so long as all surface scale is removed. A surface roughness of 1 µm (40 µin.) rms or smaller
is recommended. Clean the specimen surface carefully (see Note 4). Weigh on an analytical balance to 60.01 mg (see Note 5).
NOTE 4—Important considerations in cleaning include surface oils or greases, surface rust or corrosion, adhering abrasive particles, etc.
NOTE 5—Erosion weight loss determinations to 60.1 mg may be sufficient for particle velocities above 70 m·s−1 or sufficiently long exposure times
which lead to weight losses greater than 10 mg.
11.3 Mount the specimen in proper location and orientation in the apparatus. Subject the specimen to particle impingement for
a selected time interval, measured to an accuracy of 5 s. Remove the specimen, clean carefully (see Note 4), reweigh and calculate
the mass loss.
11.4 Repeat this process utilizing a new specimen each time to determine at least four points for a total time of at least 600 s
and plot those values as mass loss versus elapsed time. Suitable times would be 120, 240, 480, and 960 s for a material such as
Type 1020 steel. Steady state erosion should result after 60 to 120 s, depending on the material. Two examples of measured erosion
versus time curves are shown in Fig. 5.
11.5 The steady state erosion rate (see Terminology G40) is determined from the slope of the mass loss versus time plot. The
average erosion value is calculated by dividing erosion rate (mg/s) by the abrasive flow rate (g/s) and then dividing by the specimen
density (g·cm−3). Report the average erosion value as (mm3·g−1).
11.6 Repeat 11.1 at the end of a series of tests (typically every 10 tests) and more frequently if necessary.
12. Report
12.1 The test report shall include the following information:
12.1.1 Material identification: type, chemical specification, heat and processing treatment, hardness, and density. Processing
conditions shall include method of casting (such as chill or sand); method of forming (such as forging or pressing and sintering);
and the percent of ideal density (important for ceramics and powder metallurgy alloys).
12.1.2 Specimens: method of preparing and cleaning specimens, initial surface roughness, and number tested.
12.1.3 Eroding particle identification: size distribution, shape, composition, purity, source, and manufacturing method. Provide
photograph of typical collection of particles. Reference (10) can be consulted for information on methods of characterization.
12.1.4 Test conditions: particle velocity (average) and method of determination; specimen orientation relative to the impinging
stream; particle flow; particle flux; eroded area (size, shape); temperature of the specimen and particles and carrier gas; test
duration; method of determining steady-state erosion conditions; carrier gas composition, including water content, pressure, and
measurement method; and method of determining the mass of abrasive used.
12.1.5 Description of the test equipment.
12.1.6 Tabulation of erosion value and standard deviation for each specimen reported as a volume loss of material per unit mass
of abrasive (mm3·g−1).
12.2 Each test program shall include among the materials tested a reference material tested under the same conditions to permit
calculation and report of the normalized erosion rate. A suitable reference material would be Type 1020 steel (see Table 1).
G76 − 18
FIG. 5 Two Examples of Erosion versus Time for Type 1020 Steel at 30 m·s−1 and 70 m·s−1
TABLE 2 Interlaboratory Test Results (Provisional)

Laboratory Number of Average Standard Deviation Deviation from Average
Test Conditions
Number Replicates (.001 mm3/g) (.001 mm3/g) (.001 mm3/g)
Condition A: 1 9 2.240 0.420 −0.494
1020 steel, 2 9 3.130 0.130 0.396
50 µm Al2O3, 3 10 2.130 0.068 −0.604
30 m/s, 90° 4 10 3.720 0.680 0.986
0.033 g/s 5 10 2.450 0.660 −0.284
5 9.600 2.734 0.468 0.807
Number Average Average Within-Laboratory Between-Laboratory
Standard Deviation Standard Deviation
(Provisional)
Coefficient of Variation (%) = 17.1 29.5
95 % Limits = 1.31 2.26
Within-Laboratory Between-Laboratory
Condition B: 1 8 31.500 1.100 3.340
1020 steel, 2 8 23.200 0.040 −4.960
50 µm Al2O3, 3 8 22.900 0.900 −5.260
70 m/s, 90° 4 4 32.400 0.650 4.240
0.033 g/s 5 8 30.800 1.500 2.640
5 7.200 28.160 0.969 4.786
(Provisional)

95 % Limits = 2.71 13.40
Condition C: 1 8 40.000 1.300 7.640
304 stainless steel, 2 8 25.400 0.120 −6.960
50 µm Al2O3, 3 8 26.300 0.780 −6.060
70 m/s, 90° 4 4 38.000 1.200 5.640
0.033 g/s 5 8 32.100 3.000 −0.260
5 7.200 32.360 1.597 6.786
(Provisional)
95 % Limits = 4.47 19.00
G76 − 18
12.3 The report shall state clearly whether testing was done at standard conditions, shall itemize any deviations from those
conditions, and shall indicate the frequency of calibration using reference materials.
12.4 Any special occurrences or observations during testing should be noted.
13. Precision and Bias
13.1 Absolute values of erosion rates of materials are generally not available because of the wide range of possible exposure
conditions. The erosion measurement conditions established by this practice are designed to facilitate obtaining precise,
reproducible data applicable to the test conditions employed. Interlaboratory test results utilizing this practice on well-characterized
metal are given in Table 2. Examples of 95 % confidence limits for three erosion test conditions are shown in Table 2. For
Condition A, a statement of precision would be: average erosion was 2.73 × 10−3 mm3/g; 95 % repeatability limit was 1.31 × 10−3
mm3/g; 95 % reproducibility limit was 2.26 × 10−3 mm3/g.
13.2 No bias can be assigned to this test method since there is no absolute accepted value for erosion rate.
13.3 General Considerations—Participants in the interlaboratory testing that led to the statements of precision and bias given
above involve five laboratories, two different materials, two test conditions, and five replicate measurements each. Subsequent to
this testing, described in Research Report RR:G02-1003,6 data were received from another laboratory that utilized a commercial
test machine. Those data were found consistent with the results of the interlaboratory study and will be included in the research
report.
14. Keywords
14.1 erosion; erosion rate; gas jet; metal erosion; solid particle
APPENDIX
(Nonmandatory Information)
X1. ADDITIONAL INFORMATION
X1.1 This erosion test is usually applied to bulk materials. It may also be applied to coatings upon bulk substrates, if care is taken
not to penetrate the coating during the test. The test results from coated test specimens should apply to the material comprising
the coating, and thus to the coated system, as long as the coating is not altered, fragmented, or dislodged during the test.
X1.2 The standard test conditions may penetrate a coating making it difficult to rank various coatings. If this occurs, the impinging
solid particle stream can be made less aggressive by reducing the angle of incidence. Testing at 45° or even 15° has been used by
users. Some G76 users even employ a different abrasive (glass beads, 70 to 210 µm) and two times the impingement mass (20 g)
at 15° impingement angle for coating comparisons. This test has shown to not penetrate many hard coatings like PVD TiN and
glass enamels.
X1.3 In the case where this test is applied to coatings on bulk substrates, some of the test steps may need to be modified. For
example, surface preparation of the coating, like mechanical polishing, before testing may not be appropriate. Cleaning of the
surface may be constrained by the nature of the coating. In such cases, the user shall ensure that the preparation steps used for this
test do not alter the characteristics of the coating being tested. The procedures that are used shall be adequately described in the
test report.
X1.4 Normally, this test is conducted on numerous separate specimens, each eroded for a given time and condition. While not
recommended, it is possible to conduct repeated erosion tests (under the same conditions) on the same individual specimen by
carefully repositioning the specimen after eroding it, removing it for cleaning, and weighing it. In such a case, the specimen must
occupy the identical position for each test in the series; otherwise the accumulated erosion effect will not be correct.
G76 − 18
REFERENCES
(1) Young, J. P., and Ruff, A. W., Journal of Engineering Materials and Technology, Transactions of ASME, Vol 99, 1977, pp. 121–125.
(2) Hansen, J. S., in Erosion: Prevention and Useful Applications, Adler, W. F., ed., ASTM STP 664, 1979, pp. 148–162.
(3) Finnie, I., Levy, A., and McFadden, D. H., in Erosion: Prevention and Useful Applications, Adler, W. F., ed., ASTM STP 664, 1979, pp. 36–58.
(4) Wood, F. W., Journal of Testing and Evaluation, 14, 1986.
(5) Preece, C. M., ed., Erosion: Treatise on Materials Science and Technology, Vol 16 Academic Press, New York, NY, 1979.
(6) Ruff, A. W. and Ives, L. K., Wear, Vol 35, 1975, pp. 195-199.
(7) Finnie, I., Wolak, J., and Kabil, Y., Journal of Materials, Vol 2, 1967, pp. 682–700.
(8) Ninham, A. J., and Hutchins, I. M., Proceedings of the 6th International Conference on Erosion by Liquid and Solid Impact (Univ. of Cambridge,
1983) pp. 50-51.
(9) Barkalow, R. H., Goebel, J. A., and Pettit, F. S., in Erosion: Prevention and Useful Applications, Adler, W. F., ed., ASTM STP 664, 1979, pp. 163–192.
(10) Allen, T., Particle Size Measurement, Chapman and Hall, London, 1974.
(11) Ponnaganti, V., Stock, D. E., and Sheldon, G. L., Proceedings on Symposium Polyphase Flow and Transport Tech. (ASME) NY, 1980 pp 195-199.
ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned
in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk
of infringement of such rights, are entirely their own responsibility.
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This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what

changes have been made to the previous version. Because

Designation: G76 − 13 G76 − 18

Standard Test Method for

TABLE 1 Characteristics of Type 1020 Steel Reference Material

FIG. 1 Schematic Drawing of Solid Particle Erosion Equipmentof Test Rig

4. Summary of Test Method

5. Significance and Use

FIG. 2 Microstructure of 1020 Steel Reference Material

7. Test Materials and Sampling

FIG. 3 Photomicrograph of 50 µm A12O3 Particles Used in Interlaboratory Testing

9. Standard Test Conditions

11. Test Procedure

TABLE 2 Interlaboratory Test Results (Provisional)

Coefficient of Variation (%) = 3.4 17.0

X1. ADDITIONAL INFORMATION

(4) Wood, F. W., Journal of Testing and Evaluation, 14, 1986.

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