ASTM B647-23

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Designation: B647 − 10 (Reapproved 2016) B647 − 23
Standard Test Method for
Indentation Hardness of Aluminum Alloys by Means of a
Webster Hardness Gage
This standard is issued under the fixed designation B647; 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 aluminum alloys with a Webster hardness gage, Model
B.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this The values
given in parentheses after SI units are provided for information only and are not considered standard.
1.2.1 Exception—The values given in parentheses are for information only.
NOTE 1—Two other models, A and B-75, are in use, but are not covered in this test method. Model A does not provide numerical values of hardness and
Model B-75 covers only a part of the range of interest for aluminum alloys.
1.3 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 healthsafety, 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.
2. Referenced Documents
2.1 ASTM Standards:
E6 Terminology Relating to Methods of Mechanical Testing
E10 Test Method for Brinell Hardness of Metallic Materials
E18 Test Methods for Rockwell 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—The definitions of terms relating to hardness testing appearing in Terminology E6 shall be considered as
applying to the terms used in this test method.
This test method is under the jurisdiction of ASTM Committee B07 on Light Metals and Alloys and is the direct responsibility of Subcommittee B07.05 on Testing.
Current edition approved May 1, 2016April 1, 2023. Published May 2016May 2023. Originally approved in 1984. Last previous edition approved in 20102016 as
B647 – 10.B647 – 10 (2016). DOI: 10.1520/B0647-10R16. 10.1520/B0647-23.
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.
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B647 − 23
4. Significance and Use
4.1 The Webster hardness gage is portable and therefore useful for in situ determination of the hardness of fabricated parts and
individual test specimens for production control purposes. It is not as sensitive as Rockwell or Brinell hardness machines; see 10.2.
4.2 This test method should be used only as cited in applicable material specifications.
5. Apparatus (Fig. 1)
5.1 The Webster hardness gage, Model B, consists of three main parts: the frame, operating handle, and penetrator housing
assembly. The penetrator housing assembly includes the principal working parts, including the penetrator, loading spring, adjusting
nut, penetrator housing, housing key, return spring, and dial indicator.
5.2 The indentor is a hardened steel truncated cone.
5.3 The dial indicator is graduated from 1 to 20, and is actuated by the penetrator so that the higher the reading, the higher is the
hardness of the test material.
5.4 The configuration of the Webster hardness gage is such that it is operated like a pair of pliers.
5.5 The clearance between the penetrator and the anvil is about 6 mm ( ⁄4 in.), limiting the thickness of sample that can be tested.
6. Test Parts or Specimens
6.1 Any part or piece of material greater than 1 mm (0.04 in.) (0.04 in.) in thickness and equal to or less than 6 mm ( ⁄4 in.) in.)
in thickness and with a clear flat area at an edge approximately 2525 mm by 25 mm (1(1 in. by 1 in.) in size is suitable for test.
6.2 The surfaces shall be essentially parallel, smooth, clean, and free of mechanical damage. The test surface may be lightly
polished to eliminate scratches or die lines.
FIG. 1 Webster Hardness Gage, Model B
B647 − 23
6.3 The clear, flat area shall be such that there will be a clear distance of at least 3 mm ( ⁄8 in.) from the edge of the part or
specimen.
6.4 Parts or specimens with a slight taper or curvature may also be tested if a round anvil is used, as described in 8.1.1 and Fig.
2.
7. Calibration
7.1 Zero Adjustment:
7.1.1 Operate the instrument against the bare anvil and note whether or not the indicator gives the zero (full-scale) reading.
7.1.2 A correction in zero reading is normally not needed except for one of the reasons listed below:
7.1.2.1 A new penetrator has been installed,
7.1.2.2 The dial indicator is changed from one instrument to another, or
7.1.2.3 Excessive wear has taken place.
7.1.3 If an adjustment in zero is needed, turn the zero adjustment screw below the indicator dial slowly (Fig. 3), while operating
the tester against the bare anvil and maintaining handle pressure, until the hand of the dial indicator rests on the zero line (which
is located at the full-scale reading of 20).
7.1.4 The zero adjustment shouldshall never be used to make the indicator read correctly on a standard sample.
7.2 Load Spring Adjustment:
7.2.1 Measure the hardness of a standard sample of medium to low hardness, either one furnished with the tester or one developed
from reference stock; the dial shouldshall show the reading indicated for the standard within 60.5.
7.2.2 If the readings on the standard or the bare anvil, or both, do not indicate the proper values, adjust the load spring with the
special wrench provided until agreement is reached (Fig. 4).
8. Procedure
8.1 Place the test part or specimen between the penetrator and the anvil, and apply pressure to the handle.
8.1.1 If the test part or specimen has a slight taper or curvature, use a round anvil and apply the gage in such a way that the
penetrator is applied normal to the test surface and the anvil bears along a line that is parallel to the surface in contact with the
penetrator, as illustrated in Fig. 2.
8.2 Apply sufficient pressure to cause the flat face of the penetr
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