ASTM A956-06

Standard Test Method for Leeb Hardness Testing of Steel Products

SIGNIFICANCE AND USE
Hardness of a material is a poorly defined term that may have many meanings depending on the type of test performed and the expectations of the person involved. The Leeb hardness test is of the dynamic or rebound type, which primarily depends both on the plastic and on the elastic properties of the material being tested. The results obtained are indicative of the strength and dependent on the heat treatment of the material tested.  
The Leeb hardness test is a superficial determination only measuring the condition of the surface contacted. The results generated at that location do not represent the part at any other surface location and yield no information about the material at subsurface locations.
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). Note 1
The original title of this standard was "Standard Test Method for Equotip Hardness Testing of Steel Products."
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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.

General Information

• Status: Historical
• Publication Date: 31-Aug-2006
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.06 - Steel Forgings and Billets

Relations

• Replaces: ASTM A956-02 - Standard Test Method for Leeb Hardness Testing of Steel Products
• Effective Date: 01-Sep-2006
• Replaced By: ASTM A956-12 - Standard Test Method for Leeb Hardness Testing of Steel Products
• Effective Date: 15-Nov-2012
• Referred By: ASTM E110-14(2023) - Standard Test Method for Rockwell and Brinell Hardness of Metallic Materials by Portable Hardness Testers
• Effective Date: 01-Sep-2006

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: A956 − 06
StandardTest Method for
1
Leeb Hardness Testing of Steel Products
This standard is issued under the fixed designation A956; 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* (based on the type of impact device) diameter tungsten carbide
ball or diamond tipped impact body, multiplied by 1000.
1.1 This test method covers the determination of the Leeb
hardness of steel, cast steel, and cast iron (Part A), including ReboundVelocity
L 5 31000
the methods for the verification of Leeb hardness testing
ImpactVelocity
instruments (Part B), and the calibration of standardized test
The Leeb hardness number is followed by the symbol HL
blocks (Part C).
with one or more suffix characters representing the type of
NOTE 1—The original title of this standard was “Standard Test Method
impact device.
1
for Equotip Hardness Testing of Steel Products.”
3.1.3 Leeb hardness test—a dynamic hardness test method
1.2 The values stated in inch-pound units are to be regarded
using a calibrated instrument that impacts a spherically shaped
as standard. The values given in parentheses are mathematical
carbide ball or diamond tipped body with a fixed velocity
conversions to SI units that are provided for information only
(generated by a spring force) onto a surface of the material
and are not considered standard.
under test. The ratio of the rebound velocity to the impact
1.3 This standard does not purport to address all of the
velocity of the impact body is a measure of the hardness of the
safety concerns, if any, associated with its use. It is the
material under test.
responsibility of the user of this standard to establish appro-
3.1.4 surface finish—all references to surface finish in this
priate safety and health practices and determine the applica-
test method are defined as surface roughness (that is, Ra =
bility of regulatory limitations prior to use.
average roughness value, AA = arithmetic average).
2. Referenced Documents 3.1.5 verification—checking or testing the instrument to
2
ensure conformance with this test method.
2.1 ASTM Standards:
E691Practice for Conducting an Interlaboratory Study to
4. Summary of Test Method
Determine the Precision of a Test Method
4.1 During a hardness test, an impact body with a spheri-
3. Terminology
cally shaped tungsten carbide or diamond tip impacts under
spring force, the test surface from which it rebounds. The
3.1 Definitions:
impact and rebound velocities are measured when the impact
3.1.1 calibration—determination of the values of the sig-
body is approximately 1 mm from the test surface. This is
nificant operating parameters of the instrument by comparison
accomplishedbymeansofapermanentmagnetmountedinthe
with values indicated by a reference instrument or by a set of
impactbodywhich,duringthetest,movesthroughacoilinthe
reference standards.
impact device and induces an electric voltage on both the
3.1.2 Leeb hardness number—anumberequaltotheratioof
impact and rebound movements. These induced voltages are
thereboundvelocitytotheimpactvelocityofa3-mmor5-mm
proportional to the respective impact and rebound velocities.
Thequotientofthesemeasuredvoltagevaluesderivedfromthe
impact and rebound velocities, multiplied by the factor 1000
1
This test method is under the jurisdiction of ASTM Committee A01 on Steel,
produces a number which constitutes the Leeb hardness value.
Stainless Steel and RelatedAlloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets.
Current edition approved Sept. 1, 2006. Published September 2006. Originally 5. Significance and Use
approved in 1996. Last previous edition approved in 2002 as A956–02.
5.1 Hardnessofamaterialisapoorlydefinedtermthatmay
Leeb and Equotip are registered trademarks used with permission of Proceq SA.
DOI: 10.1520/A0956-06.
have many meanings depending on the type of test performed
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
andtheexpectationsofthepersoninvolved.TheLeebhardness
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
test is of the dynamic or rebound type, which primarily
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. depends both on the plastic and on the elastic properties of the
*A Summary of Changes section appears at the end of this standard
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A956 − 06
material being tested.The results obtained are
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