ASTM C1327-15(2019)

Standard Test Method for Vickers Indentation Hardness of Advanced Ceramics

SIGNIFICANCE AND USE
5.1 For advanced ceramics, Vickers indenters are used to create indentations whose surface-projected diagonals are measured with optical microscopes. The Vickers indenter creates a square impression from which two surface-projected diagonal lengths are measured. Vickers hardness is calculated from the ratio of the applied force to the area of contact of the four faces of the undeformed indenter. (In contrast, Knoop indenters are also used to measure hardness, but Knoop hardness is calculated from the ratio of the applied force to the projected area on the specimen surface.)  
5.2 Vickers indentation hardness is one of many properties that is used to characterize advanced ceramics. Attempts have been made to relate Vickers indentation hardness to other hardness scales, but no generally accepted methods are available. Such conversions are limited in scope and should be used with caution, except for special cases where a reliable basis for the conversion has been obtained by comparison tests.  
5.3 Vickers indentation diagonal lengths are approximately 2.8 times shorter than the long diagonal of Knoop indentations, and the indentation depth is approximately 1.5 times deeper than Knoop indentations made at the same force.  
5.4 Vickers indentations are influenced less by specimen surface flatness, parallelism, and surface finish than Knoop indentations, but these parameters must be considered nonetheless.  
5.5 Vickers indentations are much more likely to cause cracks in advanced ceramics than Knoop indentations. The cracks may influence the measured hardness by fundamentally altering the deformation processes that contribute to the formation of an impression, and they may impair or preclude measurement of the diagonal lengths due to excessive damage at the indentation tips or sides.  
5.6 A full hardness characterization includes measurements over a broad range of indentation forces. Vickers hardness of ceramics usually decreases with increasing indentation size o...
SCOPE
1.1 This test method covers the determination of the Vickers indentation hardness of advanced ceramics. In this test, a pointed, square-based, pyramidal diamond indenter of prescribed shape is pressed into the surface of a ceramic with a predetermined force to produce a relatively small, permanent indentation. The surface projection of the two diagonals of the permanent indentation is measured using a light microscope. The average diagonal size and the applied force are used to calculate the Vickers hardness, which represents the material’s resistance to penetration by the Vickers indenter. Hardness is computed as the ratio of the force to the contact surface area.  
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 Units—When Knoop and Vickers hardness tests were developed, the force levels were specified in units of grams-force (gf) and kilograms-force (kgf). This standard specifies the units of force and length in the International System of Units (SI); that is, force in newtons (N) and length in mm or μm. However, because of the historical precedent and continued common usage, force values in gf and kgf units are occasionally provided for information. This test method specifies that Vickers hardness be reported either in units of GPa, or a dimensionless Vickers hardness number that has implied units of kgf/mm2.  
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 R...

General Information

• Status: Published
• Publication Date: 30-Jun-2019
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: C28 - Advanced Ceramics
• Drafting Committee: C28.01 - Mechanical Properties and Performance

Relations

• Replaces: ASTM C1327-15 - Standard Test Method for Vickers Indentation Hardness of Advanced Ceramics
• Effective Date: 01-Jul-2019
• Refers: ASTM E4-14 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2014
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM E4-10 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2010
• Refers: ASTM E384-10e1 - Standard Test Method for Knoop and Vickers Hardness of Materials
• Effective Date: 01-Feb-2010
• Refers: ASTM E384-10 - Standard Test Method for Microindentation Hardness of Materials
• Effective Date: 01-Feb-2010
• Refers: ASTM E4-09a - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Nov-2009
• Refers: ASTM E384-09 - Standard Test Method for Microindentation Hardness of Materials
• Effective Date: 01-May-2009
• Refers: ASTM E4-09 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Apr-2009
• Refers: ASTM E4-08 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Dec-2008
• Refers: ASTM E177-08 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2008

Overview

ASTM C1327-15(2019) is the recognized international standard that details the test method for Vickers indentation hardness of advanced ceramics. Developed by ASTM International, this standard specifies procedures for determining the resistance of advanced ceramics to localized plastic deformation, using a diamond Vickers indenter to create a small, measurable impression on a test specimen. The test method is critical for quality assurance, research, and development in industries utilizing advanced ceramics, such as electronics, aerospace, and biomedical sectors.

The primary objective of ASTM C1327-15(2019) is to provide a consistent and reliable approach for measuring the Vickers hardness of ceramics, ensuring comparability of results across laboratories and industries. It establishes requirements for test equipment, specimen preparation, test procedures, and data reporting, reinforcing precision and repeatability in Vickers hardness measurements.

Key Topics

• Vickers Indentation Hardness Process:
  The method uses a square-based, pyramidal diamond indenter to create impressions on ceramic surfaces with a defined force. The projected diagonals of these indentations are measured using an optical microscope.

• Calculation of Hardness:
  Vickers hardness is calculated as the ratio of the applied test force to the area of contact of the four faces of the undeformed indenter. The average of two diagonal lengths from each indentation serves as the basis for this calculation.

• Measurement Conditions:
  The standard requires the use of SI units for force and length. Proper specimen preparation is essential, including surface flatness and finish, to ensure measurement accuracy. The document also addresses measurement uncertainties, including the influence of surface porosity, cracking, and microscope calibration.

• Indenter Characteristics and Test Forces:
  The document distinguishes between Vickers and Knoop indenters, specifies the geometry and sharpness of the indenter, and highlights that Vickers hardness readings typically decrease with increasing indentation size or force.

• Limits and Interferences:
  Cracking around indentations, specimen tilting, surface defects, and porosity may affect measurement accuracy. The method provides detailed guidelines for identifying and handling unsatisfactory or anomalous indentations.

Applications

ASTM C1327-15(2019) is widely used for:

• Quality Control:
  Ensuring that advanced ceramics meet specified mechanical property requirements for hardness and resistance to wear.

• Material Development:
  Assisting research and development teams in characterizing new ceramic compositions or processing methods by systematically measuring and comparing hardness.

• Failure Analysis:
  Evaluating material behavior post-failure and during product lifetime by assessing localized surface deformation and the impact of microstructural features.

• Standardization and Certification:
  Supporting procurement and certification processes by providing a uniform method for reporting Vickers hardness values in compliance with international practices.

Industries Benefiting from this Standard:

• Electronics and semiconductor manufacturing
• Aerospace and defense
• Medical device production
• Automotive and transportation
• Research laboratories and academic institutions

Related Standards

ASTM C1327-15(2019) references and aligns with several other key standards for hardness testing and ceramic evaluation, including:

• ASTM E384 - Test Method for Microindentation Hardness of Materials
• ASTM E4 - Practices for Force Verification of Testing Machines
• CEN ENV 843-4 - Advanced Technical Ceramics, Monolithic Ceramics, Mechanical Properties, Part 4: Vickers, Knoop, and Rockwell Superficial Hardness
• JIS R1610 - Testing Method for Vickers Hardness of High-Performance Ceramics
• ISO 6507/2 - Metallic Materials - Hardness Test - Vickers Test

These related standards provide additional guidance on calibration, terminology, and test equipment, ensuring comprehensive procedures for hardness measurement in both metallic and non-metallic materials.

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By adhering to ASTM C1327-15(2019), professionals can achieve reliable, reproducible Vickers hardness data for advanced ceramics, facilitating enhanced material selection, product performance, and global standardization.

Standards Content (Sample)

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: C1327 − 15 (Reapproved 2019)
Standard Test Method for
Vickers Indentation Hardness of Advanced Ceramics
This standard is issued under the fixed designation C1327; 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 2. Referenced Documents
1.1 ThistestmethodcoversthedeterminationoftheVickers 2.1 ASTM Standards:
indentation hardness of advanced ceramics. In this test, a E4Practices for Force Verification of Testing Machines
pointed, square-based, pyramidal diamond indenter of pre- E177Practice for Use of the Terms Precision and Bias in
scribed shape is pressed into the surface of a ceramic with a ASTM Test Methods
predetermined force to produce a relatively small, permanent E384Test Method for Microindentation Hardness of Mate-
indentation. The surface projection of the two diagonals of the rials
permanent indentation is measured using a light microscope. E691Practice for Conducting an Interlaboratory Study to
The average diagonal size and the applied force are used to Determine the Precision of a Test Method
calculate the Vickers hardness, which represents the material’s IEEE/ASTM SI 10American National Standard for Metric
resistance to penetration by the Vickers indenter. Hardness is Practice
computed as the ratio of the force to the contact surface area. 2.2 European Standard:
CENENV843-4AdvancedTechnicalCeramics,Monolithic
1.2 The values stated in SI units are to be regarded as
Ceramics, Mechanical Properties at Room Temperature,
standard. No other units of measurement are included in this
Part4:Vickers,KnoopandRockwellSuperficialHardness
standard.
2.3 Japanese Standard:
1.3 Units—When Knoop and Vickers hardness tests were
JIS R1610Testing Method for Vickers Hardness of High
developed, the force levels were specified in units of grams-
Performance Ceramics
force (gf) and kilograms-force (kgf). This standard specifies
2.4 ISO Standard:
the units of force and length in the International System of
ISO6507⁄2 Metallic Materials—Hardness Test—Vickers
Units (SI); that is, force in newtons (N) and length in mm or
Test—Part 2: HV0.2 to Less Than HV5
µm. However, because of the historical precedent and contin-
3. Terminology
ued common usage, force values in gf and kgf units are
occasionally provided for information. This test method speci-
3.1 Definitions:
fies thatVickers hardness be reported either in units of GPa, or
3.1.1 Vickers hardness number (HV), n—an expression of
a dimensionless Vickers hardness number that has implied
hardness obtained by dividing the force applied to a Vickers
units of kgf/mm .
indenterbythesurfaceareaofthepermanentimpressionmade
1.4 This standard does not purport to address all of the by the indenter.
safety concerns, if any, associated with its use. It is the
3.1.2 Vickers indenter, n—asquare-based,pyramidal-shaped
responsibility of the user of this standard to establish appro-
diamond indenter with face angles of 136° 00'.
priate safety, health, and environmental practices and deter-
4. Summary of Test Method
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
4.1 This test method describes an indentation hardness test
dance with internationally recognized principles on standard-
using a calibrated machine to force a pointed, square-based,
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contactASTM Customer Service at [e-mail]. ForAnnual Book ofASTM
mendations issued by the World Trade Organization Technical
Standards volume information, refer to the standard’s Document Summary page on
Barriers to Trade (TBT) Committee.
the ASTM website.
Available from European Committee for Standardization (CEN), 36 rue de
This test method is under the jurisdiction of ASTM Committee C28 on Stassart, B-1050, Brussels, Belgium, http://www.cenorm.be.
Advanced Ceramics and is the direct responsibility of Subcommittee C28.01 on Available from Japanese Standards Organization (JSA), 4-1-24 Akasaka
Mechanical Properties and Performance. Minato-Ku, Tokyo, 107-8440, Japan, http://www.jsa.or.jp.
CurrenteditionapprovedJuly1,2019.PublishedJuly2019.Originallyapproved Available from International Organization for Standardization (ISO), 1, ch. de
in 1996. Last previous edition approved in 2015 as C1327–15. DOI: 10.1520/ la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
C1327-15R19. www.iso.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1327 − 15 (2019)
pyramidal diamond indenter having specified face angles,
under a predetermined force, into the surface of the material
under test and to measure the surface-projected diagonals of
the resulting impression after removal of the force.
NOTE 1—Ageneral description of theVickers indentation hardness test
is given in Test Method E384. The present method is very similar, has
most of the same requirements, and differs only in areas required by the
special nature of advanced ceramics. This test method also has many
elements in common with standards ENV 843-4 and JIS R1610, which
are also for advanced ceramics.
5. Significance and Use
5.1 For advanced ceramics, Vickers indenters are used to
createindentationswhosesurface-projecteddiagonalsaremea-
sured with optical microscopes. The Vickers indenter creates a
square impression from which two surface-projected diagonal
lengths are measured. Vickers hardness is calculated from the
ratiooftheappliedforcetotheareaofcontactofthefourfaces
of the undeformed indenter. (In contrast, Knoop indenters are
also used to measure hardness, but Knoop hardness is calcu-
FIG. 1 Indentation Size Effect (ISE) Curves for a Ceramic (Some-
latedfromtheratiooftheappliedforcetotheprojectedareaon
times they continuously approach a plateau hardness at larger
the specimen surface.)
forces, but sometimes they can have a shift or step if cracking
5.2 Vickers indentation hardness is one of many properties occurs)
that is used to characterize advanced ceramics. Attempts have
been made to relate Vickers indentation hardness to other
6. Interferences
hardness scales, but no generally accepted methods are avail-
able.Suchconversionsarelimitedinscopeandshouldbeused
6.1 Cracking from the indentation tips can interfere with
withcaution,exceptforspecialcaseswhereareliablebasisfor determination of tip location and thus the diagonal length
the conversion has been obtained by comparison tests.
measurements.
5.3 Vickers indentation diagonal lengths are approximately
6.2 CrackingorspallingaroundtheVickersimpressionmay
2.8timesshorterthanthelongdiagonalofKnoopindentations,
occur and alter the shape and clarity of the indentation,
and the indentation depth is approximately 1.5 times deeper
especially for coarse-grained ceramics whereby grains may
than Knoop indentations made at the same force.
cleave and dislodge. The cracking may occur in a time-
dependent manner (minutes or hours) after the impression is
5.4 Vickers indentations are influenced less by specimen
made.
surface flatness, parallelism, and surface finish than Knoop
indentations, but these parameters must be considered none-
6.3 Porosity (either on or just below the surface) may
theless.
interfere with measuring Vickers hardness, especially if the
indentation falls directly onto a large pore or if the indentation
5.5 Vickers indentations are much more likely to cause
tip falls in a pore.
cracks in advanced ceramics than Knoop indentations. The
cracks may influence the measured hardness by fundamentally
6.4 At higher magnifications in the optical microscope, it
altering the deformation processes that contribute to the
may be difficult to obtain a sharp contrast between the
formation of an impression, and they may impair or preclude
indentation tip and the polished surface of some advanced
measurement of the diagonal lengths due to excessive damage
ceramics. This may be overcome by careful adjustment of the
at the indentation tips or sides.
lighting as discussed in Test Method E384.
5.6 Afull hardness characterization includes measurements
7. Apparatus
over a broad range of indentation forces. Vickers hardness of
ceramics usually decreases with increasing indentation size or 7.1 Testing Machines:
indentationforce,asshowninFig.1.Thetrendisknownasthe 7.1.1 Therearethreegeneraltypesofmachinesavailablefor
indentation size effect (ISE). Hardness approaches a plateau conducting this test. One type is a self-contained unit built for
constant hardness at sufficiently large indentation size or this purpose that uses deadweights (masses) on a pan or lever
forces. The test forces or loads that are needed to achieve a beamtocarefullyapplyforcetothetestpiece.Thereisnoload
constant hardness vary with the ceramic. The test force cell to record the force during the test sequence. The machine
specifiedinthisstandardisintendedtobesufficientlylargethat has a built-in compound optical microscope for measuring the
hardness is either close to or on the plateau, but not so large as indentation sizes. The second type is an accessory to existing
to introduce excessive cracking. A comprehensive character- compound optical microscopes. Usually, this second type is
ization of the ISE is recommended but is beyond the scope of fittedonaninverted-stagemicroscope.Thethird,moremodern
this test method, which measures hardness at a single, desig- type is a self-contained unit built for this purpose which has a
nated force. built-in load cell that controls a ram or crosshead that moves
C1327 − 15 (2019)
crack is present. A visual inspection of the resulting indentation may be
sufficient to verify the absence of defects from the shape of indentations
performed on test blocks.
7.3 Measuring Microscope:
7.3.1 The measurement system shall be constructed so that
the length of the diagonals can be determined with errors not
exceeding 60.5 µm (60.0005 mm).
NOTE 3—Stage micrometers with uncertainties less than this shall be
used to establish calibration constants for the microscope. See Test
Method E384, paragraph A1.3.3, Verification of the Indentation Measur-
ing System. Ordinary stage micrometers that are used for determining the
approximate magnification of photographs may be too coarsely ruled or
may not have the required accuracy and precision.
7.3.2 The numerical aperture (NA) of the objective lens
shall be between 0.60 and 0.90.
NOTE 4—The apparent length of a Vickers indentation increases as the
resolving power and NA of a lens increases. However, the variation is
muchlessthanthatobservedinKnoopindentations (2, 5, 6).Therangeof
FIG. 2 Vickers Indenter
NA specified by this test method corresponds to 40 to 100× objective
lenses. The higher power lenses may have higher resolution, but the
contrastbetweentheindentationtipsandthepolishedsurfacemaybeless.
theindenterintocontactwiththetestpiece.Thepeakforceand
This numerical aperture requirement is similar to, but more specific than
rate of force application can be controlled by a closed-loop that in Test Method E384. The requirement is different because many
white or grey ceramics are transparent or translucent, and tip imaging is
feedback circuit.The machine has a built-in compound optical
more difficult.
microscope for measuring the indentation sizes. Descriptions
7.3.3 A filter may be used to provide monochromatic
of the various machines are available (1-3).
illumination. Green filters have proved to be useful.
7.1.2 Design of the machine should be such that the force
7.3.4 Ifindentationdiagonalsizesaremeasuredfromdigital
applicationrate,dwelltime,andappliedforcecanbesetwithin
images acquired from a digital camera, then follow the
the limits set forth in 10.5. It is an advantage to eliminate the
manufacturer’s guidelines for use of the camera, the computer
human element whenever possible by appropriate machine
monitor, and the software. It is strongly recommended to use a
design. The machine should be designed so that vibrations
calibrated stage micrometer to verify the precision and accu-
induced at the beginning of a test will be damped out by the
racy of the length measuring procedure. The camera pixel
time the indenter touches the sample.
count, the monitor pixel count and resolution, and the length
7.1.3 The calibration of the balance beam or force applica-
measuringsoftwareshallbesuchthattherequirementsof7.3.1
tion system should be checked monthly or as needed. Inden-
can be met.
tations in standard reference materials may also be used to
check calibration when needed.
8. Test Specimens
7.2 Indenter:
8.1 The Vickers indentation hardness test is adaptable to a
7.2.1 The indenter shall meet the specifications for Vickers
wide variety of advanced ceramic specimens. In general, the
indenters. See paragraph A1.3.5.1 of Test Method E384. The
accuracy of the test will depend on the smoothness of the
four edges formed by the four faces of the indenter shall be
surface and, whenever possible, ground and polished speci-
sharp. Chamfered edges (as in Ref (4)) are not permitted. The
mens should be used. The back of the specimen shall be fixed
tip offset shall be not more than 0.5 µm in length.
so that the specimen cannot rock or shift during the test.
7.2.2 Fig.2showstheindenter.Thedepthoftheindentation
8.1.1 Thickness—As long as the specimen is over ten times
is ⁄7 the length of the diagonal. The indenter has an angle
as thick as the indentation depth, the test will not be affected.
between opposite faces of 136° 0 min (630 min).
In general, if specimens are at least 0.50 mm thick, the
7.2.3 The diamond should be examined periodically, and if
hardness will not be affected by variations in the thickness.
itislooseinthemountingmaterial,chipped,orcracked,itshall
8.1.2 Surface Finish—Specimens should have a ground and
be replaced.
polished surface. The roughness should be less than 0.1 µm
NOTE 2—This requirement is from Test Method E384 and is especially
rms. However, if one is investigating a surface coating or
pertinent to Vickers indenters used for advanced ceramics. Vickers
treatment, one cannot grind and polish the specimen.
indenters are often used at high loads in advanced ceramics in order to
create cracks. Such usage can lead to indenter damage. The diamond
NOTE 5—This requirement is necessary to ensure that the surface is flat
indenter can be examined with a scanning electron microscope. Indenters
and that the indentation is sharp. Residual stresses from polishing are of
may also be inspected with an optical microscope with at least 500×
less concern for most advanced ceramics than for glasses or metals.
power, but care should be taken to avoid damaging the microscope lens.
References (7) and (8) report that surfaces prepared with 1 µm or finer
Indentations can be made into soft copper to help determine if a chip or
diamond abrasive had no effect on measured ceramic hardness. Hardness
was only affected when the surface finish had an optically resolvable
amount of abrasive damage (7). (Extra caution may be appropriate during
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof polishing of transformation toughening ceramics, such as some zirconias,
this test method. since the effect upon hardness is not known.)
C1327 − 15 (2019)
9. Preparation of Apparatus are used (for example to measure the indentation size effect
trend), then the reporting procedure of 12.6 shall be used for
9.1 Verification of Force—Most of the machines available
each data set.
for Vickers hardness testing use a loaded beam. This beam
shall be tested for zero force. An indentation should not be
NOTE 7—“Load” and “force” are used interchangeably in this standard.
visible with zero force, but the indenter should contact the
10.4 Clean the Indenter—The indenter shall be cleaned
sample.Methodsofverifyingtheforceapplicationaregivenin
prior to and during a test series. A cotton swab with ethanol,
Practices E4.
methanol, or isopropanol may be used. Indenting into soft
9.2 Separate Verification of Force, Indenter, and Measuring
copper also may help remove debris. After each change, or
Microscope—Procedures in Test Method E384, Annex A1,
removal and replacement, of the indenter it is recommended
Verification of Knoop and Vickers Hardness Testing Machines
that a verification be performed with a reference test block.At
and Indenters, may be followed.
least two preliminary indentations should be made to ensure
that the indenter is seated properly. The results of the prelimi-
9.3 Verification by Standard Reference Materials—Standard
nary indentations shall be disregarded.
reference blocks, SRM No. 2831, of tungsten carbide that are
available from the National Institute of Standards and Tech-
NOTE 8—Ceramic powders or fragments from the ceramic test piece
nology can be used to verify that an apparatus produces a
can adhere to the diamond indenter.
Vickers hardness within 65% of the certified value.
10.5 Application of Test Force:
10.5.1 Start the machine smoothly. The rate of indenter
10. Procedure
motion prior to contact with the specimen shall be 0.015 to
10.1 Specimen Placement—Place the specimen on the stage
0.070mm/s.Ifthemachineisloadedbyanelectricalsystemor
of the machine so that the specimen will not rock or shift
a dash-pot lever system, it should be mounted on shock
during the measurement. The specimen surface shall be clean
absorbers that damp out all vibrations by the time the indenter
and free of any grease or film.
touches the specimen.
10.2 Specimen Leveling:
NOTE 9—This rate of loading is consistent with Test Method E384.
10.2.1 The surface of the specimen being tested shall lie in
10.5.2 The time of application of the full test force shall be
a plane normal to the axis of the indenter. The angle of the
10 to 15 s unless otherwise specified. After the indenter has
indenter and specimen surface should be within 2° of perpen-
been in contact with the specimen from this required dwell
dicular.
time, raise it carefully off the specimen to avoid a vibration
NOTE 6—Greater amounts of tilting produce nonuniform indentations
impact.
and invalid test results. 2° tilt will cause an asymmetrical indentation that
10.5.3 The operator shall not bump or inadvertently contact
is just noticeable, and will cause a 1% error in hardness (9).
the test machine or associated support (for example, the table)
10.2.2 If one leg of a diagonal is noticeably longer than the
during the period of indenter contact with the specimen.
other leg of the same diagonal, resulting in a deformed
10.6 Spacing of Indentations—Allow a distance of at least
indentation, misalignment is probably present and should be
fourdiagonallengthsbetweenthecentersoftheindentationsas
corrected before proceeding with any measurements. See Test
illustrated in Fig. 3. If there is cracking from the indentations,
Method E384.
the spacing shall be increased to at least five times the length
10.2.3 Leveling the specimen is facilitated if one has a
of the cracks, as shown in Fig. 3.
leveling device.
10.2.4 If the diagonal legs are unequal as described in
10.7 Acceptability of Indentations:
10.2.2, then rotate the specimen 90° and make another inden-
10.7.1 If there is excessive cracking from the indentation
tation in an untested region. If the nonsymmetrical aspect of
tipsandsides,ortheindentationisasymmetric,theindentshall
the indentations has rotated 90°, then the specimen surface is
be rejected for measurement. Fig. 4 provides guidance in this
not perpendicular to the indenter axis. If the nonsymmetrical
assessment.Ifthedifferenceofthetwodiagonallengthsd1and
natureoftheindentationremainsinthesameorientation,check
d2 is more t
...