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ASTM G98-91(1996)e1

(Test Method)

Standard Test Method for Galling Resistance of Materials

Standard Test Method for Galling Resistance of Materials

SCOPE
1.1 This test method covers a laboratory test which ranks the galling resistance of material couples. Most galling studies have been conducted on bare metals and alloys; however, non-metallics, coatings, and surface modified alloys may also 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 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
09-Oct-1996
ICS
17.040.20 - Properties of surfaces
Technical Committee
G02 - Wear and Erosion
Drafting Committee
G02.40 - Non-Abrasive Wear
Current Stage
Ref Project

Relations

Replaced By
ASTM G98-02 - Standard Test Method for Galling Resistance of Materials
Effective Date
10-Nov-2002
Referred By
ASTM G196-08(2021) - Standard Test Method for Galling Resistance of Material Couples
Effective Date
10-Oct-1996

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ASTM G98-91(1996)e1 - Standard Test Method for Galling Resistance of MaterialsASTM G98-91(1996)e1 - Standard Test Method for Galling Resistance of Materials
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ASTM G98-91(1996)e1 - Standard Test Method for Galling Resistance of Materials
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: G 98 – 91 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Galling Resistance of Materials
This standard is issued under the fixed designation G 98; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Section 11 was added editorially in October 1996.
1. Scope determined by this test method.
1.1 This test method covers a laboratory test which ranks
4. Summary of Test Method
the galling resistance of material couples. Most galling studies
4.1 This test method uses available laboratory equipment
have been conducted on bare metals and alloys; however,
capable of maintaining a constant, compressive load between
non-metallics, coatings, and surface modified alloys may also
two flat specimens, such as hydraulic or screw feed compres-
be evaluated by this test method.
sion testing machines. One specimen is slowly rotated one
1.2 This test method is not designed for evaluating the
revolution 360° relative to the other specimen. The surfaces are
galling resistance of material couples sliding under lubricated
examined for galling after sliding. The criterion for whether
conditions because galling usually will not occur under lubri-
galling occurs is the appearance of the specimens based on
cated sliding conditions using this test method.
unassisted visual examination. If the specimens have not
1.3 This standard does not purport to address all of the
galled, a new set of specimens is tested at increased load. This
safety concerns, if any, associated with its use. It is the
process is continued until galling occurs.
responsibility of the user of this standard to establish appro-
4.2 Appropriate load intervals are chosen to determine the
priate safety and health practices and determine the applica-
threshold galling stress within an acceptable range.
bility of regulatory limitations prior to use.
4.3 The higher the threshold galling stressing, the more
2. Referenced Documents galling resistant is the test couple.
2.1 ASTM Standards:
5. Significance and Use
G 40 Terminology Relating to Wear and Erosion
5.1 This test method is designed to rank material couples in
G 83 Test Method for Wear Testing with a Crossed-Cylinder
their resistance to the failure mode caused by galling and not
Apparatus
merely to classify the surface appearance of sliding surfaces.
3. Terminology 5.2 This test method should be considered when damaged
(galled) surfaces render components non-serviceable. Experi-
3.1 Definitions:
ence has shown that galling is most prevalent in sliding
3.1.1 galling—a form of surface damage arising between
systems that are slow moving and operate intermittently. The
sliding solids, distinguished by macroscopic, usually localized,
galling and seizure of threaded components is a classic
roughening and creation of protrusions above the original
example which this test method most closely simulates.
surface; it often includes plastic flow or material transfer, or
5.3 Other galling-prone examples include: sealing surfaces
both.
of value trim which may leak excessively due to galling; and
3.1.1.1 Discussion—The onset of galling usually requires
pump wear rings that may function ineffectively due to galling.
that the contact pressure exceeds some threshold value. Galling
5.4 If the equipment continues to operate satisfactorily and
can be a precursor to siezing or loss of function. The identifi-
loses dimension gradually, then mechanical wear should be
cation of galling is somewhat subjective, and complete agree-
evaluated by a different test such as the crossed cylinder Test
ment does not exist, even among experts. G40
Method (see Test Method G 83). Chain belt pins and bushings
3.2 Definitions of Terms Specific to This Standard:
are examples of this type of problem.
3.2.1 threshold galling stress—the stress midway between
5.5 This test method should not be used for quantitative or
the highest non-galled stress and the lowest galled stress as
final design purposes since many environmental factors influ-
ence the galling performance of materials in service. Lubrica-
This test method is under the jurisdiction of ASTM Committee G-2 on Wear
tion, alignment, stiffness and geometry are only some of the
and Erosion and is the direct responsibility of Subcommittee G02.40 on Non-
Abrasive Wear.
factors that can affect how materials perform. This test method
Current edition approved Feb. 22, 1991. Published April 1991. Orignally
has proven valuable in screening materials for prototypical
published as G 98 – 89. Last previous edition G 98 – 91.
2 testing that more closely simulates actual service conditions.
Annual Book of ASTM Standards, Vol 03.02.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G98
6. Apparatus
6.1 Commonly available laboratory equipment has been
used to conduct galling tests. Both Brinell hardness testers and
servo-hydraulic testing machines have proven to be satisfac-
tory as loading devices. Any apparatus that can apply and
maintain a constant compressive load should be acceptable.
7. Test Specimens
7.1 This test method uses a cylindrical flat-on-flat geometry.
One specimen is called the button (or pin) and is generally (but
not necessarily) rotated about its axis on the flat specimen
called the block.
7.2 Some typical button geometries are shown in Fig. 1.
FIG. 2 Schematic Diagram of Galling Test Set-Up
7.3 The only critical dimension is diameter “B’’ of the
contact area. The 6.4-mm (0.25-in.) diameter hole accommo-
any scale, oil film, or foreign matter. The following cleaning
dates a ball bearing for alignment purposes during the test. All
technique is suggested for metallic specimens: clean the button
other dimensions may be varied to the user’s convenience.
and block in trichloroethane, ultrasonically, if possible; a
7.4 The block specimen must have sufficient area to accom-
methanol rinse may be used to remove any traces of trichlo-
modate at least one test; however, most users have found that
roethane residue. Materials with open grains (some powder
blocks of length 76 mm (3 in.) to 152 mm (6 in.) are ideal for
metals) must be dried to remove all traces of the cleaning
multiple tests. A reasonable width is 19 mm (0.75 in.).
solvent which may be entrapped in the material. Demagnetize
Thickness is not critical. T
...

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5.1 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.  
5.2 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 which this test method most closely simulates.  
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5.1 The amount of wear in any system will, in general, depend upon the number of system factors such as the applied load, machine characteristics, sliding speed, sliding distance, the environment, and the material properties. The value of any wear test method lies in predicting the relative ranking of material combinations. Since the pin-on-disk test method does not attempt to duplicate all the conditions that may be experienced in service (for example, lubrication, load, pressure, contact geometry, removal of wear debris, and presence of corrosive environment), there is no insurance that the test will predict the wear rate of a given material under conditions differing from those in the test.  
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1.1 This test method covers a laboratory procedure for determining the wear of materials and friction during sliding using a pin-on-disk apparatus. Materials are tested in pairs under nominally non-abrasive conditions. The principal areas of experimental attention in using this type of apparatus to measure wear are described.  
1.2 This test method standard uses a specific set of test parameters (load, sliding speed, materials, etc.) that were then used in an interlaboratory study (ILS), the results of which are given here (Tables 1 and 2). (This satisfies the ASTM form in that “The directions for performing the test should include all of the essential details as to apparatus, test specimen, procedure, and calculations needed to achieve satisfactory precision and bias.”) Any user should report that they “followed the requirements of ASTM G99,” where that is true.  
1.3 Now it is often found in practice that users may follow all instructions given here, but choose other test parameters, such as load, speed, materials, environment, etc., and thereby obtain different test results. Such a use of this standard is encouraged as a means to improve wear testing methodology. However, it must be clearly stated in any report that, while the directions and protocol in Test Method G99 were followed (if true), the choices of test parameters were different from Test Method G99 values, and the test results were therefore also different from the Test Method G99 results. This use should be described as having “followed the procedure of ASTM G99.” All test parameters that were used in such case must be stated.  
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SIGNIFICANCE AND USE
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1.3 The coefficient of friction values averaged between the test reaching full test pressure and the time of the onset of adhesion or the end of tests run for a predetermined time period are recorded. Systems are ranked by their average coefficients of friction before adhesion occurs.  
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5.1 The severity of abrasive wear in any system will depend upon the abrasive particle size, shape, and hardness, the magnitude of the stress imposed by the particle, and the frequency of contact of the abrasive particle. In this practice these conditions are standardized to develop a uniform condition of wear which has been referred to as scratching abrasion (1 and 3). The value of the practice lies in predicting the relative ranking of various materials of construction in an abrasive environment. Since the practice does not attempt to duplicate all of the process conditions (abrasive size, shape, pressure, impact, or corrosive elements), it should not be used to predict the exact resistance of a given material in a specific environment. Its value lies in predicting the ranking of materials in a similar relative order of merit as would occur in an abrasive environment. Volume loss data obtained from test materials whose lives are unknown in a specific abrasive environment may, however, be compared with test data obtained from a material whose life is known in the same environment. The comparison will provide a general indication of the worth of the unknown materials if abrasion is the predominant factor causing deterioration of the materials.
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5.1 Rolling friction like sliding friction depends upon many factors. It is a system effect that involves the nature of the rolling surface and the counterface. The sliding friction force (F) is usually considered to be the sum of forces arising from deformations of surface features (Fs), from attractive forces (atomic, molecular, etc.) at contact points (Fa) and force from interaction of films and particulates on the rubbing surfaces (Ff):
The rolling friction force includes these force contributions plus effects from the relative stiffness of the contacting surfaces, the diameter (curvature) of the spherical shape (ball, orange, etc.) and other factors. Because there are so many factors involved in a rolling tribosystem, rolling resistance can best be quantified by an actual test of the sphere of interest on the intended counterface, as in this test method.  
5.2 There are countless applications where it is important to quantify the rolling characteristics of a particular spherical shape on a particular surface. The interlaboratory tests conducted for this test method were performed on hardened steel balls like those used in ball bearings. This test method could be used to assess the effect of different counterface surfaces on the rolling characteristics of balls for ball bearings. Conversely, it could be used as a quality control test on balls. Surface imperfections/defects/films, etc. on the balls can affect how they roll: the distance traveled on a common counterface.  
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1.1.1 Steel balls on a surface plate were used in interlaboratory tests (see Appendix X1). Golf balls on a green, soccer and lacrosse balls on playing surfaces, bowling balls on an a lane, basketballs on hardwood, and marbles on composite surface were tested in the development of this test method, but the test applies to any sphere rolling on any flat horizontal surface.  
1.1.2 The rolling friction of spheres on horizontal surfaces is affected by the spherical shape’s stiffness, radius of curvature, surface texture, films on the surface, the nature of the counterface surface; there are many factors to consider. This test method takes all of these factors into consideration. The spherical shape of interest is rolled on the surface of interest using a standard ramp to initiate rolling and standard techniques to measure and treat the rolled distance after leaving the ramp.  
1.1.3 This test method produces a rolling resistance number on a specific spherical shape on a specific surface. It is intended for comparing similar tribosystems. For example, the rolling resistances of marbles on a particular surface are not to be compared with the rolling resistance of soccer balls on grass, because their masses and diameters are very different as are the counterface surfaces on which they roll.  
1.1.4 Different launch ramps are appropriate for different types of spherical shapes. If a sphere of interest cannot be accommodated with using one of the launch ramps discussed in Appendix X1 and Appendix X2, a different launch ramp can be developed and added with future revisions to this test method.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measu...

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ASTM G115-10(2018)(Guide)
Standard Guide for Measuring and Reporting Friction Coefficients

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5.1 In this guide, factors that shall be considered in conducting a valid test for the determination of the coefficient of friction of a tribosystem are covered, and the use of a standard reporting format for friction data is encouraged.  
5.2 The factors that are important for a valid test may not be obvious to non-tribologists, and the friction tests referenced will assist in selecting the apparatus and test technique that is most appropriate to simulate a tribosystem of interest.  
5.3 The tribology literature is replete with friction data that cannot readily be used by others because specifics are not presented on the tribosystem that was used to develop the data. The overall goal of this guide is to provide a reporting format that will enable computer databases to be readily established. These databases can be searched for material couples and tribosystems of interest. Their use will significantly reduce the need for each laboratory to do its own testing. Sufficient information on test conditions will be available to determine applicability of the friction data to the engineer's specific needs.
SCOPE
1.1 This guide covers information to assist in the selection of a method for measuring the frictional properties of materials. Requirements for minimum data and a format for presenting these data are suggested. The use of the suggested reporting form will increase the long-term usefulness of the test results within a given laboratory and will facilitate the exchange of test results between laboratories. It is hoped that the use of a uniform reporting format will provide the basis for the preparation of handbooks and computerized databases.  
1.2 This guide applies to most solid materials and to most friction measuring techniques and test equipment.  
1.3 Units—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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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.

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ASTM
ASTM G171-03(2017)(Test Method)
Standard Test Method for Scratch Hardness of Materials Using a Diamond Stylus

SIGNIFICANCE AND USE
5.1 This test method is intended to measure the resistance of solid surfaces to permanent deformation under the action of a single point (stylus tip). It is a companion method to quasi-static hardness tests in which a stylus is pressed into a surface under a certain normal load and the resultant depth or impression size is used to compute a hardness number. Scratch hardness numbers, unlike quasi-static hardness numbers, involve a different combination of properties of the surface because the indenter, in this case a diamond stylus, moves tangentially along the surface. Therefore, the stress state under the scratching stylus differs from that produced under a quasi-static indenter. Scratch hardness numbers are in principle a more appropriate measure of the damage resistance of a material to surface damage processes like two-body abrasion than are quasi-static hardness numbers.  
5.2 This test method is applicable to a wide range of materials. These include metals, alloys, and some polymers. The main criteria are that the scratching process produces a measurable scratch in the surface being tested without causing catastrophic fracture, spallation, or extensive delamination of surface material. Severe damage to the test surface, such that the scratch width is not clearly identifiable or that the edges of the scratch are chipped or distorted, invalidates the use of this test method to determine a scratch hardness number. Since the degree and type of surface damage in a material may vary with applied load, the applicability of this test to certain classes of materials may be limited by the maximum load at which valid scratch width measurements can be made.  
5.3 The resistance of a material to abrasion by a single point may be affected by its sensitivity to the strain rate of the deformation process. Therefore, this test is conducted under low stylus traversing speeds. Use of a slow scratching speed also minimizes the possible effects of frictional heating.  
5.4 This...
SCOPE
1.1 This test method covers laboratory procedures for determining the scratch hardness of the surfaces of solid materials. Within certain limitations, as described in this guide, this test method is applicable to metals, ceramics, polymers, and coated surfaces. The scratch hardness test, as described herein, is not intended to be used as a means to determine coating adhesion, nor is it intended for use with other than specific hemispherically-tipped, conical styli.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard may involve hazardous materials, operations, and equipment. 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.

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