ASTM A833-19

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Designation: A833 − 17 A833 − 19
Standard Test Method for
Indentation Hardness of Metallic Materials by Comparison
Hardness Testers
This standard is issued under the fixed designation A833; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers the determination of indentation hardness of metallic materials using comparison hardness testers.
1.2 This test method applies only to those portable comparison hardness testers that use test bars that have been standardized
according to Test Method E10 as a basis for comparison.
1.3 Calibration of test bars, used for comparison to determine hardness numbers, is also covered by this test method.
1.4 The impression force used during comparison hardness testing is normally an impact load applied by striking a hammer on
the appropriate areas as outlined in the manufacturer’s instructions.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety problems, 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.
1.7 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.
2. Referenced Documents
2.1 ASTM Standards:
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
E10 Test Method for Brinell Hardness of Metallic Materials
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions:
3.1.1 test bar, n—that part of the testing apparatus which is used to determine a comparable hardness used in calculation of test
part hardness.
3.1.2 test part, n—the item for which a hardness test determination is being performed.
4. Significance and Use
4.1 The comparative hardness test is an empirical dynamic indentation hardness test. Comparative hardness tests provide useful
information about metallic materials. This information may correlate to tensile strength, wear resistance, ductility, heat treatment
condition, or other physical characteristics of metallic materials, and may be useful in quality control and selection of materials.
4.2 Comparative hardness testing at a specific location on a test part may not represent the physical characteristics of the whole
test part or end product.
This test method is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.06
on Steel Forgings and Billets.
Current edition approved Nov. 1, 2017Nov. 1, 2019. Published December 2017November 2019. Originally approved in 1984. Last previous edition approved in 20142017
as A833 – 08aA833 – 17.(2014). DOI: 10.1520/A0833-17.10.1520/A0833-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 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 the ASTM website.
*A Summary of Changes section appears at the end of this standard
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A833 − 19
5. Apparatus
5.1 Comparison hardness testers are used principally for testing articles that are too large or unwieldy to be tested in the usual
types of testing machines, for testing parts of fixed structures, or for testing under any conditions that require that the indenting
force be applied in a direction other than vertical.
5.1.1 Required equipment includes an apparatus that contains the impression ball and a slot or spacing to insert the test bar, a
structure to apply the impact (anvil), and an impacting tool, normally a hammer. This apparatus is designed to allow a ball
impression to be produced on the standard rod simultaneously with one produced on the piece to be tested. Comparison of the
impression diameters together with the hardness of the test bar is used to determine hardness of the test part.
5.1.2 The structure to convey the impact to the test bar, impression ball, and test part is designed with the striking surface for
the impacting tool centered directly above the location of the impression ball.
5.1.3 The apparatus may also be designed to include an extension for stabilization.
5.1.4 The Brinell hardness of the test bar used, as determined by Test Method E10 and Test Methods and Definitions A370, shall
be within 610 % of the anticipated Brinell hardness of the test part, and of the same general type of material.
5.1.5 Impression Ball:
5.1.5.1 The diameter of the impression ball shall be 10 6 0.01 mm.
5.1.5.2 The ball shall be made from steel hardened within the range of 60 to 67 HRC and shall be capable of being used in a
reasonable number of tests without incurring damage that could affect the results. Use of a tungsten carbide ball may result in
fracture or spalling of the ball.
5.1.5.3 The ball shall be inspected regularly according to the equipment manufacturer’s recommendations to ensure accuracy.
5.2 Measuring Microscope—The divisions of the micrometer scale of the microscope, or other measuring devices used for
measuring the impression diameter, shall be such as to permit the direct measuring of the diameter to 0.1 mm and the estimation
of the diameter to 0.05 mm.
6. Test Parts
6.1 Test parts by this hardness testing test method vary greatly in form since it is frequently desirable to make the impression
upon a test part to be used in the finished product rather than upon a sample test specimen.
6.1.1 Dimensions—The thickness of the tested part shall be such that no bulge or other marking showing the effect of the load
appears on the side of the piece opposite the impression. In any event, the thickness of the test part shall be at least ten times the
depth of the indentation. The minimum width shall be at least two and one half times the diameter of the indentation.
6.1.2 Finish—When necessary, the surface on which the impression is to be made shall be filed, ground, machined, or polished
with abrasive material so that the edge of the impression shall be defined clearly enough to permit the measurement of the diameter
to the specified accuracy. Take care to avoid overheating or cold working the surface. Sufficient metal shall be removed to eliminate
decarburized metal.
6.2 Support—All test parts shall be adequately supported to prevent any movement or deflection during application of the
impact load.
7. Verification of Apparatus and Calibration of Test Bars
7.1 Verification of Apparatus—The hardness-testing apparatus (including test bars) shall be verified by performing tests on
Brinell blocks that have been standardized according to the requirements of Test Method E10.
7.1.1 Full verification of the apparatus shall be performed prior to use when new, and upon replacement of the impression ball.
The full verification shall include testing at least one Brinell test block 3 times. The average of the three measurements shall be
within 65 % of the Brinell value of the test block.
7.1.2 Periodic verifications are recommended at the beginning of each day the comparative tester is used, or during usage as
deemed necessary. Periodic verifications should be performed using Brinell test blocks within 615 % of the expected Brinell
hardness of the test parts being tested. One measurement is satisfactory for periodic testing. The result of the periodic test
measurement should be within 65 % of the Brinell value of the test block to be considered to be in compliance with this test
method.
7.2 Calibration of Test Bars—The Brinell hardness of the test bars shall be determined by the test bar manufacturer using a 10
mm diameter ball and a 3000 kg load according to Test Method E10 on each of the four faces of the test bar at approximately the
mid-length of the bar. If the test bar is too soft to permit the use of a 3000 kg load, then a 1500 kg load shall be used. The hardness
values obtained shall not vary from each other by more than 62 %. The ends of the bar shall be permanently marked with the
average hardness value, as well as the applied load if the 1500 kg load was used by the manufacturer prior to shipment.
8. Procedure
8.1 Assemble the test bar into the apparatus making sure a minimum distance of no less than 5 mm will exist between diameter
of the impression to be made and any other indentations on the face. Minimum distance of the indentation diameter from the edge
of the test part shall be 12.5 mm. If the apparatus is equipped with a presetting bar stop, ensure the fixture is properly in place.
A833 − 19
Place the apparatus on the surface of the component to be tested a
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