ASTM E2546-07

Standard Practice for Instrumented Indentation Testing

SIGNIFICANCE AND USE
IIT Instruments are used to quantitatively measure various mechanical properties of thin coatings and other volumes of material when other traditional methods of determining material properties cannot be used due to the size or condition of the sample. This practice will establish the basic requirements for those instruments. It is intended that IIT based test methods will be able to refer to this practice for the basic requirements for force and displacement accuracy, reproducibility, verification, reporting, etc., that are necessary for obtaining meaningful test results.
IIT is not restricted to specific test forces, displacement ranges, or indenter types. This practice covers the requirements for a wide range of nano, micro, and macro (see ISO 14577-1) indentation testing applications. The various IIT instruments are required to adhere to the requirements of the practice within the their specific design ranges.
SCOPE
1.1 This practice defines the basic steps of Instrumented Indentation Testing (IIT) and establishes the requirements, accuracies, and capabilities needed by an instrument to successfully perform the test and produce the data that can be used for the determination of indentation hardness and other material characteristics. IIT is a mechanical test that measures the response of a material to the imposed stress and strain of a shaped indenter by forcing the indenter into a material and monitoring the force on, and displacement of, the indenter as a function of time during the full loading-unloading test cycle.
1.2 The operational features of an IIT instrument, as well as requirements for Instrument Verification Annex A1), Standardized Reference Blocks (Annex A2) and Indenter Requirements (Annex A3) are defined. This practice is not intended to be a complete purchase specification for an IIT instrument.
1.3 With the exception of the non-mandatory Appendix X4, this practice does not define the analysis necessary to determine material properties. That analysis is left for other test methods. Appendix X4 includes some basic analysis techniques to allow for the indirect performance verification of an IIT instrument by using test blocks.
1.4 Zero point determination, instrument compliance determination and the indirect determination of an indenters area function are important parts of the IIT process. The practice defines the requirements for these items and includes non-mandatory appendixes to help the user define them.
1.5 The use of deliberate lateral displacements is not included in this practice (that is, scratch testing).
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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: 14-Jul-2007
• ICS: 19.100 - Non-destructive testing
• Technical Committee: E28 - Mechanical Testing
• Drafting Committee: E28.06 - Indentation Hardness Testing

Relations

• Replaced By: ASTM E2546-07e1 - Standard Practice for Instrumented Indentation Testing
• Effective Date: 15-Jul-2007

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: E2546 − 07
StandardPractice for
Instrumented Indentation Testing
This standard is issued under the fixed designation E2546; 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 priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This practice defines the basic steps of Instrumented
Indentation Testing (IIT) and establishes the requirements,
2. Referenced Documents
accuracies, and capabilities needed by an instrument to suc-
2.1 ASTM Standards:
cessfullyperformthetestandproducethedatathatcanbeused
E3Guide for Preparation of Metallographic Specimens
for the determination of indentation hardness and other mate-
E74Practice of Calibration of Force-Measuring Instruments
rial characteristics. IIT is a mechanical test that measures the
for Verifying the Force Indication of Testing Machines
response of a material to the imposed stress and strain of a
E92TestMethodforVickersHardnessofMetallicMaterials
shaped indenter by forcing the indenter into a material and
(Withdrawn 2010)
monitoring the force on, and displacement of, the indenter as a
E384Test Method for Knoop and Vickers Hardness of
function of time during the full loading-unloading test cycle.
Materials
1.2 TheoperationalfeaturesofanIITinstrument,aswellas
E1875Test Method for Dynamic Young’s Modulus, Shear
requirements for Instrument Verification (Annex A1), Stan-
Modulus, and Poisson’s Ratio by Sonic Resonance
dardized Reference Blocks (AnnexA2) and Indenter Require-
E1876Test Method for Dynamic Young’s Modulus, Shear
ments (AnnexA3) are defined. This practice is not intended to
Modulus, and Poisson’s Ratio by Impulse Excitation of
be a complete purchase specification for an IIT instrument.
Vibration
1.3 With the exception of the non-mandatory Appendix X4,
2.2 American Bearings Manufacturer Association Stan-
this practice does not define the analysis necessary to deter-
dard:
mine material properties. That analysis is left for other test
ABMA 10-1988Metal Balls
methods. Appendix X4 includes some basic analysis tech-
2.3 ISO Standards:
niques to allow for the indirect performance verification of an
ISO 14577-1, -2, -3, -4Metallic Materials—Instrumented
IIT instrument by using test blocks.
Indentation Tests for Hardness and Material Properties
1.4 Zero point determination, instrument compliance deter-
ISO 376Metallic Materials—Calibration of Force-Proving
mination and the indirect determination of an indenter’s area
Instruments for the Verification of Uniaxial Testing Ma-
function are important parts of the IIT process. The practice
chines
defines the requirements for these items and includes non-
mandatory appendixes to help the user define them.
3. Terminology
1.5 The use of deliberate lateral displacements is not in-
3.1 Definitions of Terms Specific to This Standard:
cluded in this practice (that is, scratch testing).
3.1.1 contact stiffness, n—theinstantaneouselasticresponse
of the material over the area of contact with the indenter.
1.6 The values stated in SI units are to be regarded as
Contact stiffness can be determined from the slope of line 3 in
standard. No other units of measurement are included in this
Fig. 1.
standard.
1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
responsibility of the user of this standard to establish appro-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
The last approved version of this historical standard is referenced on
ThispracticeisunderthejurisdictionofASTMCommitteeE28onMechanical www.astm.org.
Testing and is the direct responsibility of Subcommittee E28.06 on Indentation Available from American Bearing Manufacturers Association (ABMA), 2025
Hardness Testing. M Street, NW Suite 800 Washington, DC 20036, http://www.abma-dc.org.
Current edition approved July 15, 2007. Published July 2007. DOI: 10.1520/ Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
E2546-07. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2546 − 07
3.1.6 instrumented indentation test (IIT), n—an indentation
test where the force applied to an indenter and the resultant
displacementoftheindenterintothesampleisrecordedduring
the loading and unloading process for post test analysis.
3.1.7 nominal area function, n—area function determined
from measurement of the gross indenter geometry.
3.1.8 refined area function, n—area function determined
indirectly by a technique such as the one described in Appen-
dix X3.
3.1.9 test cycle, n—aseriesofoperationsatasinglelocation
on the test sample. The cycle is specified in terms of either
applied test force or displacement as a function of time. The
test cycle may include any of the following operations:
approach of the indenter towards the test sample, singular or
1. Increasing test force
multiple loading, dwell, and unloading cycles.
2. Removal of the test force
3. Tangent to curve 2 at F
max
3.1.10 test data, n—for this practice it will consist, at the
FIG. 1 IIT Procedure Shown Schematically
minimum, of a set of related force/displacement/time data
points.
3.1.11 zero point, n—the force-displacement-time reference
3.1.2 force displacement curve, n—a common plot of the
point when the indenter first contacts the sample and the force
force applied to an indenter and the resultant depth of penetra-
is zero. A course zero point is an approximate value used as
tion.Thisplotisgeneratedfromdatacollectedduringtheentire
part of an analysis to determine a refined value.
loading and unloading cycle. (See Fig. 1.)
3.2 Indentation Symbols and Designations (see Fig. 2):
3.1.3 indentation radius [a], n—the in-plane radius, at the
Symbol Designation Unit
surfaceofthetestpiece,ofthecircularimpressionofanindent
α Angle, specific to shape of pyramidal indenter °
(see Annex A3)
created by a spherical indenter. For non-circular impressions,
a Radius of projected indentation µm
the indentation radius is the radius of the smallest circle
R Radius of spherical indenter (see Annex A3)µm
capable of enclosing the indentation. The indentation radius is
F Test force applied to sample N
F Maximum value of F N
normally used as a guide for spacing of indentations. max
h Indenter displacement into the sample µm
3.1.4 indenter area function [Λ], n—mathematical function
h Maximum value of h µm
max
h Depth over which the indenter and specimen are µm
thatrelatestheprojected(cross-section)areaoftheindentertip c
in contact during the force application
to the distance from the apex of the tip as measured along the
h Permanent recovered indentation depth after µm
p
central axis.
removal of
test force
3.1.5 instrument compliance, n—the flex or reaction of the 2
A Surface area of indenter in contact with material µm
s
load frame, actuator, stage, indenter, anvil, etc., that is the A Projected (cross section) area of indenter at µm
p
depth h
c
result of the application of a test force to the sample.
NOTE 1—The symbols shown are the same for pointed and spherical indenters.
FIG. 2 Schematic Cross-Section of an IIT Indentation
E2546 − 07
ever is greater. The estimated uncertainty in the displacement
Symbol Designation Unit
h Point of intersection of line 3 with the h axis (see µm
r
at the zero point should not exceed 1% of the maximum
Fig. 1)
indenter displacement (h ) or 2 nm, which ever is greater. If
max
S Contact stiffness N/µm
t Time relative to the zero point s the estimated uncertainty in the displacement at the zero point
is larger than both criteria, its value and the influence of its
4. Summary of Practice
value on reported mechanical properties shall be noted in the
test report. See Appendix X1 for information on how to
4.1 This practice defines the details of the IIT test and the
determine the zero point.
requirements and capabilities for instruments that perform IIT
6.2.2 Sample Positioning—The positioning of the sample
tests. The necessary components are defined along with the
required accuracies required to obtain useful results. Verifica- beingtestedrelativetothecenterlineofthetestforceiscritical
to obtaining good results. The testing instrument shall be
tion methods are defined to insure that the instruments are
performing properly. It is intended that ASTM (or other) Test designed to allow the centerline of the test force to be normal
to the sample surface at the point of indentation.
Methods will refer to this practice when defining different
calculations or algorithms that determine one or more material
6.2.3 Indenters—Indentersnormallyconsistsofacontacttip
characteristics that are of interest to the user.
and a suitable holder. The tip should have a hardness and
modulus that significantly exceeds the materials being tested.
5. Significance and Use
The holder shall be manufactured to support the contact point
without any unpredictable deflections that could affect the test
5.1 IIT Instruments are used to quantitatively measure
results.The holder shall allow proper mounting in the actuator
various mechanical properties of thin coatings and other
and position the contact point correctly for the application of
volumes of material when other traditional methods of deter-
the test force. The contact tip and holder could be a one or
mining material properties cannot be used due to the size or
multi-piece design. A variety of indenter shapes, such as
condition of the sample. This practice will establish the basic
pyramids, cones, and spheres, can be used for IIT Testing.
requirementsforthoseinstruments.ItisintendedthatIITbased
Annex A3 defines the requirements for the most commonly
test methods will be able to refer to this practice for the basic
used indenters. Whenever they are used the requirements of
requirements for force and displacement accuracy,
AnnexA3shallbefollowed.Otherindentershapescanbeused
reproducibility, verification, reporting, etc., that are necessary
provided they are defined in a standardized Method or de-
for obtaining meaningful test results.
scribed in the test report.
5.2 IIT is not restricted to specific test forces, displacement
ranges,orindentertypes.Thispracticecoverstherequirements
NOTE 2—The nominal indenter geometry, as described in Annex A3,
maybesufficientlyaccurateforagivenanalysis.Inmanycases,however,
for a wide range of nano, micro, and macro (see ISO 14577-1)
a refined area function that more accurately represents the shape of the
indentation testing applications. The various IIT instruments
indenter used may be necessary to provide the desired results (see A3.7).
arerequiredtoadheretotherequirementsofthepracticewithin
6.2.4 Imaging Device (Optional)—In applications where it
the their specific design ranges.
is desirable to accurately locate the indentation point on the
6. Apparatus sample or observe the indent, an imaging device such as an
optical or atomic force microscope may prove helpful. The
6.1 General—The force, displacement and time are simul-
device should be mounted such that locations can be identified
taneously recorded during the full sequence of the test. An
quickly and accurately.
analysis of the recorded data must be done to yield relevant
informationaboutthesample.Whenavailable,relevantASTM
6.3 Data Storage and Analysis Capabilities—The apparatus
test methods for the analysis should be followed for compara-
shall have the following capabilities:
tive results.
6.3.1 Force/Displacement/TimeMeasurement—Acquireand
NOTE 1—The user is encouraged to refer to the manufacturer’s
store raw force, displacement and time data during each test.
instructionmanualtounderstandtheexactdetailsofthetestsandanalysis
6.3.2 Data Correction—When necessary, conversion of the
performed.
raw data defined in 6.3.1 to corrected force (F), displacement
6.2 Testing Instrument—The instrument shall be able to be
(h), and time (t) data as defined in 3.2. The conversion shall
verifiedaccordingtotherequirementsdefinedinAnnexA1and
consider at least the following parameters: Zero point determi-
have the following features.
nation (see Appendix X1), instrument compliance (see Appen-
6.2.1 Test Forces/Displacements—The instrument shall be
dix X2) and thermal drift.
able to apply operator selectable test forces or displacements
6.3.3 Indenter Shape Function—Utilize an appropriate in-
within its usable range. The controlled parameters can vary
denter shape function if necessary (see Appendix X3).
either continuously or step by step. The application of the test
6.3.4 Test Result Generation:
force shall be smooth and free from any unintended vibrations
6.3.4.1 Perform the desired analysis on the raw or corrected
or abnormalities that could adversely affect the results. The
data to obtain useful test results. When available, relevant
approach,loading,anddataacquisitionratesshallbecontrolled
ASTM or ISO 14577 test methods should be used.
to the extent that is required to obtain meaningful estimates of
force and displacement uncertainties at the zero point. The 6.3.4.2 Determine indentation modulus (E ) according to
IT
estimated uncertainty in the force at the zero point shall not the Test Method defined in Appendix X4 or another method
exceed 1% of the maximum test force (F ) or 2 µN, which that produces similar results.
max
E2546 − 07
7. Test Piece 8.4 Define the Test Cycle—The test cycle parameters shall
be chosen with respect to the following considerations:
7.1 Surface Finish—The surface finish of the sample will
8.4.1 The forces generated by the dynamic motion of the
directly affect the test results.The test should be performed on
indenter mass shall not adversely affect the accuracy of the
a flat specimen with a polished or otherwise suitably prepared
results.Thisisparticularlytrueatthepointofcontactwhenthe
surface. Any contamination will reduce the precision and
intentionally applied forces are small.
accuracy of the test. The user should consider the indent size
8.4.2 The test cycle force and displacement values used in
when determining the proper surface finish.
the test result analysis, except those used for zero point
7.2 Surface Preparation—The preparation of the surface
determinati
...