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ASTM G171-03(2017)

(Test Method)

Standard Test Method for Scratch Hardness of Materials Using a Diamond Stylus

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.

General Information

Status
Published
Publication Date
31-Oct-2017
ICS
17.040.20 - Properties of surfaces
Technical Committee
G02 - Wear and Erosion
Drafting Committee
G02.30 - Abrasive Wear
Current Stage
Ref Project

Relations

Refers
ASTM G40-15 - Standard Terminology Relating to Wear and Erosion
Effective Date
01-Nov-2015
Referred By
ASTM D7027-20 - Standard Test Method for Evaluation of Scratch Resistance of Polymeric Coatings and Plastics Using an Instrumented Scratch Machine
Effective Date
01-Nov-2017
Referred By
ASTM D7187-20 - Standard Test Method for Measuring Mechanistic Aspects of Scratch/Mar Behavior of Paint Coatings by Nanoscratching
Effective Date
01-Nov-2017
Referred By
ASTM D3363-22 - Standard Test Method for Film Hardness by Pencil Test
Effective Date
01-Nov-2017

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ASTM G171-03(2017) - Standard Test Method for Scratch Hardness of Materials Using a Diamond StylusASTM G171-03(2017) - Standard Test Method for Scratch Hardness of Materials Using a Diamond Stylus
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ASTM G171-03(2017) - Standard Test Method for Scratch Hardness of Materials Using a Diamond Stylus
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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: G171 − 03 (Reapproved 2017)
Standard Test Method for
1
Scratch Hardness of Materials Using a Diamond Stylus
This standard is issued under the fixed designation G171; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers laboratory procedures for de- 3.1 Definitions—For definitions of terms applicable to this
termining the scratch hardness of the surfaces of solid materi- standard see Terminology G40.
als. Within certain limitations, as described in this guide, this
3.2 Definitions of Terms Specific to This Standard:
test method is applicable to metals, ceramics, polymers, and
3.2.1 scratch hardness number, n—a quantity, expressed in
coated surfaces.The scratch hardness test, as described herein,
units of force per unit area, that characterizes the resistance of
is not intended to be used as a means to determine coating
a solid surface to penetration by a moving stylus of given tip
adhesion, nor is it intended for use with other than specific
radius under a constant normal force and speed; namely,
hemispherically-tipped, conical styli.
kP
1.2 The values stated in SI units are to be regarded as HS 5
P 2
w
standard. No other units of measurement are included in this
where:
standard.
HS = scratch hardness number,
P
1.3 This standard may involve hazardous materials,
k = a geometrical constant,
operations, and equipment. This standard does not purport to
P = applied normal force, and
address all of the safety concerns, if any, associated with its
w = scratch width.
use. It is the responsibility of the user of this standard to
NOTE 1—The constant k may be chosen to include conversion factors
establish appropriate safety, health, and environmental prac-
forexpressing HS inunitsofGPa.For HS inGPa, Pingrams-force,and
P P
tices and determine the applicability of regulatory limitations
w in µm, k = 24.98.
prior to use.
3.2.2 scratching force, n—the force that opposes relative
1.4 This international standard was developed in accor-
motion between a moving stylus and the surface that is being
dance with internationally recognized principles on standard-
scratched by that stylus, and which is perpendicular to the
ization established in the Decision on Principles for the
normal force exerted by the stylus.
Development of International Standards, Guides and Recom-
3.2.3 stylus drag coeffıcient, n—in scratch testing, the di-
mendations issued by the World Trade Organization Technical
mensionless ratio of the scratching force to the normal force
Barriers to Trade (TBT) Committee.
applied to the stylus; namely,
2. Referenced Documents
F
scr
D 5
2 sc
P
2.1 ASTM Standards:
G40Terminology Relating to Wear and Erosion
where:
G117Guide for Calculating and Reporting Measures of
D = stylus drag coefficient,
sc
Precision Using Data from Interlaboratory Wear or Ero-
F = scratching force, and
3
scr
sion Tests (Withdrawn 2016)
P = normal force.
1
4. Summary of Test Method
This test method is under the jurisdiction of ASTM Committee G02 on Wear
and Erosion and is the direct responsibility of Subcommittee G02.30 on Abrasive
4.1 This test involves producing a scratch in a solid surface
Wear.
by moving a diamond stylus of specified geometry along a
Current edition approved Nov. 1, 2017. Published December 2017. Originally
ε2
approved in 2003. Last previous edition approved in 2009 as G171–03 (2009) .
specified path under a constant normal force and with a
DOI: 10.1520/G0171-03R17.
constant speed. The average width of the scratch is measured,
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and that value is used to compute the scratch hardness number
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 in units of pressure.
the ASTM website.
3
4.2 As an option, the scratching force may be measured
The last approved version of this historical standard is referenced on
www.astm.org. during this test and used to compute a stylus drag coefficient,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
G171 − 03 (2017)
which is a dimensionless measure of the resistance of the test 6. Apparatus
surface to deformation by a tangentially-moving stylus.
6.1 General Description—The apparatus consist
...

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SCOPE
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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.  
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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.  
5.3 Industrial applications of this test method can include assessing conveying surfaces for spherical or nearly special parts: check valve balls, cabinet knobs, Christmas ornaments, toilet floats, etc. Many medical devices use special shapes where rolling characteristics are a consideration. Similarly, many pharmaceutical products (pills) are spherical or nearly spherical in shape, and this test method can be used to assess rolling characteristics for conveying or other reasons such ...
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1.1 This test method covers the use of an angled launch ramp to initiate rolling of a sphere or nearly spherical shape on a flat horizontal surface to determine the rolling friction characteristics of a given spherical shape on a given surface.  
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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SIGNIFICANCE AND USE
4.1 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.  
4.2 The use of this test method will fall in one of two categories: (1) the test(s) will follow all particulars of the standard, and the results will have been compared to the ILS data (Table 2), or (2) the test(s) will have followed the procedures/methodology of Test Method G99 but applied to other materials or using other parameters such as load, speed, materials, etc., or both. In this latter case, the results cannot be compared to the ILS data (Table 2). Further, it must be clearly stated what choices of test parameters/materials were chosen.
SCOPE
1.1 This test method covers a laboratory procedure for determining the wear of materials 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. The coefficient of friction may also be determined.  
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.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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.

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  • Standard
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ASTM
ASTM G223-23(Test Method)
Standard Test Method for Measuring Friction and Adhesive Wear Properties of Lubricated and Nonlubricated Materials Using the Twist Compression Test (TCT)

SIGNIFICANCE AND USE
5.1 This test method is designed to rank material couples, surface treatments, and lubricants by CFT and in their resistance to adhesive wear. Since adhesive wear is a complex phenomenon and stochastic in nature, it is essential to evaluate surfaces to confirm the presence of adhesion.  
5.2 This test method should be considered when evaluating the impact of changes in a process or application that is prone to adhesive wear, including any combination of scoring, galling, and plowing. These modes of failure commonly occur under sliding contact, at high contact stress, and, when applicable, at lubricant starvation.  
5.3 The TCT is often used to evaluate the ability of material couples, surface treatments, coatings, and lubricants to prevent or reduce adhesive wear in metalworking operations including deep drawing, extrusion, and pipe bending. Other applications in which the test may be effective are loader bucket bushings, gear teeth at startup, and low-clearance pumps.  
5.4 This test method is best used as a comparative screening tool. The ranking of performance produced by the TCT correlates well with the ranking in many applications.3 However, since the test is a bench test and not directly reproducing any specific application, TCT results should be only used as an indicator of the tendency for adhesive wear to occur. TCT is a useful screening test for comparing the effectiveness of material couples, surface treatments, coatings, and lubricant formulations before process testing and field trials.
SCOPE
1.1 This test method covers laboratory procedures for determining the coefficient of friction (COF) and resistance of materials to adhesion under flat sliding using the twist compression test (TCT). This test method ranks material couples, surface treatments, coatings, and lubricant combinations by COF and their resistance to adhesion.  
1.2 The time until adhesion for the materials under the test conditions are reported and used to quantify the tribocouple’s adhesion resistance and susceptibility to galling or scuffing. Systems of higher adhesion resistance will give longer time until failure.  
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.  
1.4 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard except psi and pounds in Table 1.  
1.5 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.  
1.6 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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