ASTM A956-02
(Test Method)Standard Test Method for Leeb Hardness Testing of Steel Products
Standard Test Method for Leeb Hardness Testing of Steel Products
SCOPE
1.1 This test method covers the determination of the Leeb hardness of steel, cast steel, and cast iron (Part A), including the methods for the verification of Leeb hardness testing instruments (Part B), and the calibration of standardized test blocks (Part C).
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
Note 1—The original title of this standard was "Standard Test Method for Equotip Hardness Testing of Steel Products".
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Designation: A 956 – 02
Standard Test Method for
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Leeb Hardness Testing of Steel Products
This standard is issued under the fixed designation A 956; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope (generated by a spring force) onto a surface of the material
under test. The ratio of the rebound velocity to the impact
1.1 This test method covers the determination of the Leeb
velocity of the impact body is a measure of the hardness of the
hardness of steel, cast steel, and cast iron (Part A), including
material under test.
the methods for the verification of Leeb hardness testing
3.1.4 surface finish—all references to surface finish in this
instruments (Part B), and the calibration of standardized test
test method are defined as surface roughness (that is, Ra =
blocks (Part C).
average roughness value, AA = arithmetic average).
1.2 The values stated in inch-pound units are to be regarded
3.1.5 verification—checking or testing the instrument to
as the standard. The values given in parentheses are for
ensure conformance with this test method.
information only.
NOTE 1—The original title of this standard was “Standard Test Method 4. Significance and Use
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for Equotip Hardness Testing of Steel Products”.
4.1 Hardness of a material is a poorly defined term that may
have many meanings depending on the type of test performed
2. Referenced Documents
andtheexpectationsofthepersoninvolved.TheLeebhardness
2.1 ASTM Standards:
test is of the dynamic or rebound type, which primarily
E 691 Practice for Conducting an Interlaboratory Study to
depends both on the plastic and on the elastic properties of the
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Determine the Precision of a Test Method
material being tested. The results obtained are indicative of the
strength and dependent on the heat treatment of the material
3. Terminology
tested.
3.1 Definitions:
4.2 The Leeb hardness test is a superficial determination
3.1.1 calibration—determination of the values of the sig-
only measuring the condition of the surface contacted. The
nificant operating parameters of the instrument by comparison
results generated at that location do not represent the part at
with values indicated by a reference instrument or by a set of
any other surface location and yield no information about the
reference standards.
material at subsurface locations.
3.1.2 Leeb hardness number—anumberequaltotheratioof
the rebound velocity to the impact velocity of a 3-mm or 5-mm
A. GENERAL DESCRIPTION OF INSTRUMENTS
(based on the type of impact device) diameter tungsten carbide
AND TEST PROCEDURE FOR LEEB HARDNESS
ball or diamond tipped impact body, multiplied by 1000.
TEST
Rebound Velocity
L 5 3 1000
5. Apparatus
Impact Velocity
5.1 The instrument used for Leeb hardness testing consists
of(1)animpactdevicethatisequippedwithatungstencarbide
The Leeb hardness number is followed by the symbol HL
ball or synthetic diamond tipped impact body, an induction coil
with one or more suffix characters representing the type of
velocity measuring assembly, and a support ring, and ( 2)an
impact device.
electronic digital display hardness indicating device.
3.1.3 Leeb hardness test—a dynamic hardness test method
5.2 Impact Devices—There are six types of impact devices
using a calibrated instrument that impacts a spherically shaped
used in Leeb hardness testing. These are the D, DC, D+15, G,
carbide ball or diamond tipped body with a fixed velocity
C, and the E impact units. Brief descriptions of the types of
devices and their common applications are given in Appendix
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This test method is under the jurisdiction of ASTM Committee A01 on Steel,
X1.
Stainless Steel, and RelatedAlloys and is the direct responsibility of Subcommittee
5.3 Summary of Test Method—During a hardness test, an
A01.06 on Steel Forgings and Billets.
impact body with a spherically shaped tungsten carbide or
Current edition approved July 10, 2002. Published August 2002. Originally
diamond tip impacts under spring force, the test surface from
published as A 956–97. Last previous edition A 956–00.
Leeb and Equotip are registered trademarks used with permission of Proceq SA.
which it rebounds. The impact and rebound velocities are
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Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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A956–02
measured when the impact body is approximately 1 mm from different for different materials. Testing to this procedure shall
the test surface.This is accomplished by means of a permanent be performed wi
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