ASTM G76-18

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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
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Designation: G76 − 13 G76 − 18
Standard Test Method for
Conducting Erosion Tests by Solid Particle Impingement
Using Gas Jets
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). 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:
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 Microgrits
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.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
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.
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
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
3 −1
specimen (mm ·g ).
3 −1 3 −1
3.2.2 Normalized Erosion Rate—erosion value (mm ·g ) of specimen material divided by erosion value (mm ·g ) 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 nozzle consists of a tube about 1.5 mm inner diameter, 50 mm long,
manufactured from an erosion resistant material such as WC, A1 O , and so forth. Erosion of the nozzle during service shall be
2 3
monitored and shall not exceed 10 % increase in the initial diameter.
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, 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 series
shall be tested periodically using specified (see Section 9) 50 μm A1 O particles to verify the satisfactory performance of the
2 3
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 A1 O particles is shown in Fig. 3. The range of erosion results
2 3
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.
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.
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 A1 O Particles Used in Interlaboratory Testing
2 3
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 A1 O , equivalent to those used in the interlaboratory test series
2 3
(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.
−1
9.1.4 The abrasive particle velocity shall be 30 6 2 m·s , 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
−2 −1
mg·mm ·s 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.
The sole source of supply of the
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