ASTM G196-08

Standard Test Method for Galling Resistance of Material Couples

SIGNIFICANCE AND USE
This test method is designed to rank material couples in their resistance to the failure mode caused by galling and not merely to classify the surface appearance of sliding surfaces.
This test method has been shown to have higher repeatability than Test Method G 98 in determining the galling resistance. Test Method G 98 can be used for initial ranking of galling resistance.
5.3 This test method should be considered when damaged (galled) surfaces render components non-serviceable. Experience has shown that galling is most prevalent in sliding systems that are slow moving and operate intermittently. The galling and seizure of threaded components is a classic example that this test method most closely simulates.
5.4 Other galling-prone examples include: sealing surfaces of valves that may leak excessively due to galling and pump wear rings that may function ineffectively due to galling.
5.5 If the equipment continues to operate satisfactorily and loses dimension gradually, then galling is not present, and the wear should be evaluated by a different test method.
5.6 This test method should not be used for quantitative or final design purposes, since many environmental factors influence the galling performance of materials in service. Lubrication, alignment, stiffness, and geometry are only some of the factors that can affect how materials perform. This test method has proven valuable in screening materials for prototypical testing that more closely simulates actual service conditions.
SCOPE
1.1 This test method covers a laboratory test that ranks the galling resistance of material couples using a quantitative measure. Bare metals, alloys, nonmetallic materials, coatings, and surface modified materials may be evaluated by this test method.
1.2 This test method is not designed for evaluating the galling resistance of material couples sliding under lubricated conditions, because galling usually will not occur under lubricated sliding conditions using this test method.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Jun-2008
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: G02 - Wear and Erosion
• Drafting Committee: G02.40 - Non-Abrasive Wear

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G196 − 08
Standard Test Method for
Galling Resistance of Material Couples
This standard is issued under the fixed designation G196; 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 roughening and creation of protrusions above the original
surface; it often includes plastic flow or material transfer, or
1.1 This test method covers a laboratory test that ranks the
both.
galling resistance of material couples using a quantitative
measure. Bare metals, alloys, nonmetallic materials, coatings,
3.2.3 triboelement—one of two or more solid bodies that
and surface modified materials may be evaluated by this test
comprise a sliding, rolling, or abrasive contact, or a body
method.
subjected to impingement or cavitation. (Each triboelement
contains one or more tribosurfaces.)
1.2 This test method is not designed for evaluating the
galling resistance of material couples sliding under lubricated
3.2.4 tribosurfaces—any surface (of a solid body) that is in
conditions, because galling usually will not occur under
moving contact with another surface or is subjected to im-
lubricated sliding conditions using this test method.
pingement or cavitation.
1.3 The values stated in SI units are to be regarded as
3.2.5 tribosystem—any system that contains one or more
standard. No other units of measurement are included in this
triboelements, including all mechanical, chemical, and envi-
standard.
ronmental factors relevant to the tribological behavior. (See
also triboelement.)
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.3 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.3.1 galling —stress at which the probability of galling
priate safety and health practices and determine the applica-
occurring on one or both of the test specimens is 50%.
bility of regulatory limitations prior to use.
4. Summary of Test Method
2. Referenced Documents
4.1 This test method uses available laboratory equipment
2.1 ASTM Standards:
capable of maintaining a constant, compressive load between
G40 Terminology Relating to Wear and Erosion
two flat specimens, such as hydraulic compression testing
G98 Test Method for Galling Resistance of Materials
machines. One specimen is slowly rotated one complete
revolution relative to the other specimen. The surfaces are
3. Terminology
examined for galling after sliding. The criterion for whether
3.1 Definitions used in this test method given in Terminol-
galling occurs is the appearance of the specimens based on
ogy G40.
unassisted visual examination.
3.2 Definitions:
4.2 Appropriate load intervals are chosen to determine the
3.2.1 apparent area of contact—areaofcontactbetweentwo
threshold galling stress within an acceptable range.
solid surfaces defined by the boundaries of their macroscopic
interface.
4.3 The higher the Galling value, the more galling resis-
3.2.2 galling—form of surface damage arising between tant is the test couple.
sliding solids, distinguished by macroscopic, usually localized,
5. Significance and Use
5.1 This test method is designed to rank material couples in
This test method is under the jurisdiction of ASTM Committee G02 on Wear
and Erosion and is the direct responsibility of Subcommittee G02.40 on Non- their resistance to the failure mode caused by galling and not
Abrasive Wear.
merely to classify the surface appearance of sliding surfaces.
Current edition approved July 1, 2008. Published August 2008. DOI: 10.1520/
G0196-08.
5.2 This test method has been shown to have higher
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
repeatability than Test Method G98 in determining the galling
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
resistance. Test Method G98 can be used for initial ranking of
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. galling resistance.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G196 − 08
5.3 This test method should be considered when damaged the shape of an annulus. One specimen is rotated about its axis
(galled) surfaces render components non-serviceable. Experi- and the other is held fixed.
ence has shown that galling is most prevalent in sliding
7.2 A typical geometry of the specimen is shown in Fig. 2.
systems that are slow moving and operate intermittently. The
galling and seizure of threaded components is a classic 7.3 The critical dimensions of the specimens are the
example that this test method most closely simulates. 12.70-mm outer diameter and the 6.375-mm hole. All other
dimensions may be varied to the user’s convenience. The hex
5.4 Other galling-prone examples include: sealing surfaces
shape shown on the specimen is not required, however, it does
of valves that may leak excessively due to galling and pump
provide a convenient means of gripping the specimens during
wear rings that may function ineffectively due to galling.
testing.
5.5 If the equipment continues to operate satisfactorily and
7.4 A critical feature of the specimens is the flatness. The
loses dimension gradually, then galling is not present, and the
contact surface of the specimen shall be flat within 0.005 mm
wear should be evaluated by a different test method.
to ensure area contact. Flatness can be measured using a dial
5.6 This test method should not be used for quantitative or
indicator.
final design purposes, since many environmental factors influ-
ence the galling performance of materials in service.
8. Procedure
Lubrication, alignment, stiffness, and geometry are only some
of the factors that can affect how materials perform. This test 8.1 An overall view of the galling test setup is shown inFig.
method has proven valuable in screening materials for proto- 3.
typical testing that more closely simulates actual service
8.2 Cleaning—Immediately prior to testing, clean the test
conditions.
surfaces of the new specimens using a procedure that will
remove any scale, oil film, or foreign matter. The following
6. Apparatus
cleaning technique is suggested for metallic specimens:
6.1 Commonly available laboratory equipment has been
8.2.1 Clean the specimens in an ultrasonic cleaner using
used to conduct galling tests.Any apparatus that can apply and
mild ultrasonic cleaning detergent and warm water for 10 min.
maintain a constant compressive load should be acceptable.
8.2.2 Rinse the specimens thoroughly with water.
The use of a displacement controlled machines is generally not
8.2.3 Repeat this process using fresh solution.
acceptable for this test because small variations in displace-
8.2.4 After the final cleaning, dry the specimens with a
ment of the specimens leads to large changes in the applied
lint-free wipe.
load.
8.2.5 Remove any spotting with acetone and a lint-free
6.2 The alignment of the specimens is accomplished via the
wipe.
alignment pin shown in Fig. 1.This pin is readily fabricated by
press fit of a tooling ball into a drill rod or similar shaft with an
8.3 Mount the new specimens in the loading device. Lightly
appropriately sized hole machined into the end of the pin.
load the specimens. Twist the specimens relative to each other
Tooling balls are relatively inexpensive and readily available
approximately 45° to ensure proper seating of the wear
from industrial suppliers.
surfaces.
6.3 A hardened steel ball with a diameter of 9.53 mm is
8.4 Apply the selected load and rotate one specimen one
required for the testing procedure.
revolution using an open-end wrench or other tool in order to
grip the specimens. A mechanized system may also be used to
7. Test Specimen
rotateonespecimenrelativetotheother.Thismayallowtorque
7.1 This test metho
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