ASTM C748-98(2015)
(Test Method)Standard Test Method for Rockwell Hardness of Graphite Materials
Standard Test Method for Rockwell Hardness of Graphite Materials
SIGNIFICANCE AND USE
4.1 A Rockwell L scale hardness number is a number derived from the net increase in depth of impression as the load on a 6.3500 mm ± 0.0025 mm diameter steel-ball indenter is increased from a fixed 10 kg minor load to a 60 kg major load and then returned to the minor load.
4.2 A Rockwell hardness number is directly related to the indentation hardness of a material; the higher the Rockwell L scale reading, the harder the material. The test is useful in the evaluation and the manufacturing control of carbon and graphite materials.
SCOPE
1.1 This test method covers Rockwell L scale hardness testing of graphite materials with grain size less than 0.8 mm and a hardness range between 0 and 120.
1.2 Test Methods E18 shall be followed except where otherwise indicated.
1.3 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C748 − 98 (Reapproved 2015) An American National Standard
Standard Test Method for
1
Rockwell Hardness of Graphite Materials
This standard is issued under the fixed designation C748; 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 4.2 A Rockwell hardness number is directly related to the
indentation hardness of a material; the higher the Rockwell L
1.1 This test method covers Rockwell L scale hardness
scale reading, the harder the material. The test is useful in the
testing of graphite materials with grain size less than 0.8 mm
evaluation and the manufacturing control of carbon and graph-
and a hardness range between 0 and 120.
ite materials.
1.2 Test Methods E18 shall be followed except where
otherwise indicated.
5. Apparatus
1.3 The values stated in SI units are to be regarded as
5.1 Rockwell Hardness Tester, calibrated in accordance with
standard. No other units of measurement are included in this
the requirements of Section 7.
standard.
5.2 Rockwell Hardness Tester Anvil, appropriate for the
1.4 This standard does not purport to address all of the
material shall be used as the specimen base plate.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
6. Test Specimen
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 6.1 The recommended test specimen shall be flat and have a
minimum thickness of 6.35 mm.
2. Referenced Documents
6.2 The test surface roughness shall not exceed 3175 nm
2
2.1 ASTM Standards:
arithmetical average.
E18 Test Methods for Rockwell Hardness of Metallic Ma-
6.3 The test surface to opposite face parallelism for flat
terials
specimens shall be within 1 %. For all other specimen shapes,
E171 Practice for Conditioning and Testing Flexible Barrier
the test surface must be maintained normal to the direction of
Packaging
load application.
3. Summary of Test Method
7. Verification of Calibration
3.1 The specimen is held in position and the load is applied.
Final position of the indicator on the scale is observed and 7.1 Level the Rockwell hardness tester in accordance with
recorded as the hardness number. the manufacturer’s instructions.
7.2 The adjustment of speed-of-load application is of great
4. Significance and Use
importance. Adjust the dashpot on the Rockwell tester so that
4.1 A Rockwell L scale hardness number is a number
the operating handle completes its travel in 4 s to 7 s with no
derivedfromthenetincreaseindepthofimpressionastheload
specimen on the machine or no load applied by the indenter to
on a 6.3500 mm 6 0.0025 mm diameter steel-ball indenter is
the anvil. The major load shall be 60 kg for this calibration.
increased from a fixed 10 kg minor load to a 60 kg major load
When so adjusted, the period taken for the mechanism to come
and then returned to the minor load.
to a stop with the specimen in place will vary from 5 s to 15 s,
depending upon the particular specimen, the indenter, and the
load used. The operator should check the instrument manual
1
This test method is under the jurisdiction of ASTM Committee D02 on
for this adjustment.
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.F0 on Manufactured Carbon and Graphite Products.
7.3 Select a test block for Rockwell L scale ball-type
Current edition approved Oct. 1, 2015. Published December 2015. Originally
ɛ1
indenters and make five impressions on the test surface of the
approved in 1973. Last previous edition approved in 2010 as C748 – 98 (2010) .
DOI: 10.1520/C0748-98R15.
block. Compare the average of these five tests against the
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
hardness calibration of the block. If the error is more than 62
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
hardness numbers, the machine or penetrator, or both, must be
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. checked to determine and correct the cause of error.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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C748 − 98 (2015)
8. Conditioning 11.1.1 If the table on which a Rockwell hardness tester is
mounted is subject to vibration, such as is experienced in the
8.1 Allow the specimen(s) to reach equilibrium with room-
vicinity of other machines, the tester should be effectively
temperature air, and test
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: C748 − 98 (Reapproved 2010) C748 − 98 (Reapproved 2015)An American National Standard
Standard Test Method for
1
Rockwell Hardness of Graphite Materials
This standard is issued under the fixed designation C748; 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
ε NOTE—Updated units of measurement throughout editorially in May 2010.
1. Scope
1.1 This test method covers Rockwell L scale hardness testing of graphite materials with grain size less than 0.8 mm 0.8 mm
and a hardness range between 0 and 120.
1.2 Test Methods E18 shall be followed except where otherwise indicated.
1.3 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
E18 Test Methods for Rockwell Hardness of Metallic Materials
E171 Practice for Conditioning and Testing Flexible Barrier Packaging
3. Summary of Test Method
3.1 The specimen is held in position and the load is applied. Final position of the indicator on the scale is observed and recorded
as the hardness number.
4. Significance and Use
4.1 A Rockwell L scale hardness number is a number derived from the net increase in depth of impression as the load on a
6.35006.3500 mm 6 0.0025-mm0.0025 mm diameter steel-ball indenter is increased from a fixed 10-kg10 kg minor load to a
60-kg60 kg major load and then returned to the minor load.
4.2 A Rockwell hardness number is directly related to the indentation hardness of a material; the higher the Rockwell L scale
reading, the harder the material. The test is useful in the evaluation and the manufacturing control of carbon and graphite materials.
5. Apparatus
5.1 Rockwell Hardness Tester, calibrated in accordance with the requirements of Section 7.
5.2 Rockwell Hardness Tester Anvil, appropriate for the material shall be used as the specimen base plate.
6. Test Specimen
6.1 The recommended test specimen shall be flat and have a minimum thickness of 6.35 mm.6.35 mm.
6.2 The test surface roughness shall not exceed 3175-nm3175 nm arithmetical average.
6.3 The test surface to opposite face parallelism for flat specimens shall be within 1 %. For all other specimen shapes, the test
surface must be maintained normal to the direction of load application.
1
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.F0 on Manufactured Carbon and Graphite Products.
Current edition approved May 1, 2010Oct. 1, 2015. Published November 2010December 2015. Originally approved in 1973. Last previous edition approved in 20052010
ɛ1
as C748–98(2005).C748 – 98 (2010) . DOI: 10.1520/C0748-98R10E01.10.1520/C0748-98R15.
2
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
C748 − 98 (2015)
7. Verification of Calibration
7.1 Level the Rockwell hardness tester in accordance with the manufacturer’s instructions.
7.2 The adjustment of speed-of-load application is of great importance. Adjust the dashpot on the Rockwell tester so that the
operating handle completes its travel in 44 s to 7 s 7 s with no specimen on the machine or no load applied by the indenter to the
anvil. The major load shall be 60 kg 60 kg for this calibration. When so adjusted, the period taken for the mechanism to come to
a stop with the specimen in place will vary from 55 s to 15 s, 15 s, depending upon the particular specimen, the indenter, and the
load used. The operator should check the instrument manual for this adjustment.
7.3 Select a test block for Rockwell L scale ball-type indenters and make five impressions on the test surface o
...
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