ASTM A956/A956M-22

Standard Test Method for Leeb Hardness Testing of Steel Products

SIGNIFICANCE AND USE
5.1 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.  
5.2 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  
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
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, 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.

General Information

• Status: Published
• Publication Date: 31-Aug-2022
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.13 - Mechanical and Chemical Testing and Processing Methods of Steel Products and Processes

Standards Content (Sample)

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.
Designation:A956/A956M −22
Standard Test Method for
1
Leeb Hardness Testing of Steel Products
This standard is issued under the fixed designationA956/A956M; 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* E177Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.1 This test method covers the determination of the Leeb
E691Practice for Conducting an Interlaboratory Study to
hardness of steel, cast steel, and cast iron (Part A), including
Determine the Precision of a Test Method
the methods for the verification of Leeb hardness testing
instruments (Part B), and the calibration of standardized test
3. Terminology
blocks (Part C).
3.1 Definitions:
NOTE 1—The original title of this standard was “Standard Test Method
3.1.1 calibration—determination of the values of the sig-
1
for Equotip Hardness Testing of Steel Products.”
nificant operating parameters of the instrument by comparison
1.2 The values stated in either SI units or inch-pound units
with values indicated by a reference instrument or by a set of
are to be regarded separately as standard. The values stated in
reference standards.
each system are not necessarily exact equivalents; therefore, to
3.1.2 Leeb hardness number—anumberequaltotheratioof
ensure conformance with the standard, each system shall be
the rebound velocity to the impact velocity of a 0.118 in.
used independently of the other, and values from the two
[3mm] or 0.197 in. [5 mm] (based on the type of impact
systems shall not be combined.
device) diameter spherically shaped tungsten carbide, silicon
1.3 This standard does not purport to address all of the
nitride, or diamond tipped impact body, multiplied by 1000.
safety concerns, if any, associated with its use. It is the
ReboundVelocity
responsibility of the user of this standard to establish appro-
L 5 31000
ImpactVelocity
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
The Leeb hardness number is followed by the symbol HL
1.4 This international standard was developed in accor-
with one or more suffix characters representing the type of
dance with internationally recognized principles on standard-
impact device.
ization established in the Decision on Principles for the
3.1.3 Leeb hardness test—a dynamic hardness test method
Development of International Standards, Guides and Recom-
using a calibrated instrument that impacts a spherically shaped
mendations issued by the World Trade Organization Technical
tungsten carbide, silicon nitride, or diamond tipped body with
Barriers to Trade (TBT) Committee.
a fixed velocity (generated by a spring force) onto a surface of
the material under test.The ratio of the rebound velocity to the
2. Referenced Documents
impactvelocityoftheimpactbodyisameasureofthehardness
2
2.1 ASTM Standards:
of the material under test.
E140Hardness Conversion Tables for Metals Relationship
3.1.4 surface finish—all references to surface finish in this
Among Brinell Hardness, Vickers Hardness, Rockwell
test method are defined as surface roughness (that is, Ra =
Hardness, Superficial Hardness, Knoop Hardness, Sclero-
average roughness value, AA = arithmetic average).
scope Hardness, and Leeb Hardness
3.1.5 verification—checking or testing the instrument to
ensure conformance with this test method.
1
This test method is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and RelatedAlloys and is the direct responsibility of Subcommittee
4. Summary of Test Method
A01.13 on Mechanical and Chemical Testing and Processing Methods of Steel
Products and Processes.
4.1 During a hardness test, an impact body with a spheri-
Current edition approved Sept. 1, 2022. Published September 2022. Originally
cally shaped tungsten carbide, silicon nitride, or diamond tip
approved in 1996. Last previous edition approved in 2017 as A956/A956M–17A.
impacts, after being propelled to the specified velocity, the test
Leeb and Equotip are registered trademarks used with permission of Proceq SA.
DOI: 10.1520/A0956_A0956M-22.
surface from which it rebounds. The impact and rebound
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
velocitiesaremeasuredwhentheimpactbodyisapproximately
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
0.039in.[1mm]fromthetestsurface.Thisisaccomplishedby
Standards volume information, refer to the standard’s
...

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.
Designation: A956/A956M − 17a A956/A956M − 22
Standard Test Method for
1
Leeb Hardness Testing of Steel Products
This standard is issued under the fixed designation A956/A956M; 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 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
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 either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
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, 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
2.1 ASTM Standards:
E140 Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness,
Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness
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 calibration—determination of the values of the significant operating parameters of the instrument by comparison with values
indicated by a reference instrument or by a set of reference standards.
1
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 A01.13
on Mechanical and Chemical Testing and Processing Methods of Steel Products and Processes.
Current edition approved Nov. 1, 2017Sept. 1, 2022. Published December 2017September 2022. Originally approved in 1996. Last previous edition approved in 2017 as
A956/A956M – 17.A956/A956M – 17A.
Leeb and Equotip are registered trademarks used with permission of Proceq SA. DOI: 10.1520/A0956_A0956M-17A.10.1520/A0956_A0956M-22.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary pageon the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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A956/A956M − 22
3.1.2 Leeb hardness number—a number equal to the ratio of the rebound velocity to the impact velocity of a 0.118 in. [3 mm] or
0.197 in. [5 mm] (based on the type of impact device) diameter spherically shaped tungsten carbide, silicon nitride, or diamond
tipped impact body, multiplied by 1000.
Rebound Velocity
L 5 31000
Impact Velocity
The Leeb hardness number is followed by the symbol HL with one or more suffix characters representing the type of impact
device.
3.1.3 Leeb hardness test—a dynamic hardness test method using a calibrated instrument that impacts a spherically shaped tungsten
carbide, silicon nitride, or diamond tipped body with a fixed velocity (generated by a spring force) onto a surface of the material
under test. The ratio of the rebound velocity to the impact velocity of the impact body is a measure of the hardness of the material
under test.
3.1.4 surface finish—all references to surface finish in this test method are defined as surface roughness (that is, Ra =
...