EN ISO 6508-1:2005

SLOVENSKI STANDARD
01-marec-2006
1DGRPHãþD
SIST EN ISO 6508-1:2000
Kovinski materiali – Preskus trdote po Rockwellu – 1. del: Preskusna metoda
(skale A, B, C, D, E, F, G, H, K, N, T) (ISO 6508-1:2005)
Metallic materials - Rockwell hardness test - Part 1: Test method (scales A, B, C, D, E, F,
G, H, K, N, T) (ISO 6508-1:2005)
Metallische Werkstoffe - Härteprüfung nach Rockwell - Teil 1: Prüfverfahren (Skalen A,
B, C, D, E, F, G, H, K, N, T) (ISO 6508-1:2005)
Matériaux métalliques - Essai de dureté Rockwell - Partie 1: Méthode d'essai (échelles
A, B, C, D, E, F, G, H, K, N, T) (ISO 6508-1:2005)
Ta slovenski standard je istoveten z: EN ISO 6508-1:2005
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 6508-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2005
ICS 77.040.10 Supersedes EN ISO 6508-1:1999
English Version
Metallic materials - Rockwell hardness test - Part 1: Test method
(scales A, B, C, D, E, F, G, H, K, N, T) (ISO 6508-1:2005)
Matériaux métalliques - Essai de dureté Rockwell - Partie 1: Metallische Werkstoffe - Härteprüfung nach Rockwell - Teil
Méthode d'essai (échelles A, B, C, D, E, F, G, H, K, N, T) 1: Prüfverfahren (Skalen A, B, C, D, E, F, G, H, K, N, T)
(ISO 6508-1:2005) (ISO 6508-1:2005)
This European Standard was approved by CEN on 14 December 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6508-1:2005: E
worldwide for CEN national Members.

Foreword
This document (EN ISO 6508-1:2005) has been prepared by Technical Committee ISO/TC 164
"Mechanical testing of metals" in collaboration with Technical Committee ECISS/TC 1 "Steel -
Mechanical testing", the secretariat of which is held by AFNOR.

This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by June 2006, and conflicting national
standards shall be withdrawn at the latest by June 2006.

This document supersedes EN ISO 6508-1:1999.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Endorsement notice
The text of ISO 6508-1:2005 has been approved by CEN as EN ISO 6508-1:2005 without any
modifications.
INTERNATIONAL ISO
STANDARD 6508-1
Second edition
2005-12-15
Metallic materials — Rockwell hardness
test —
Part 1:
Test method (scales A, B, C, D, E, F, G, H,
K, N, T)
Matériaux métalliques — Essai de dureté Rockwell —
Partie 1: Méthode d'essai (échelles A, B, C, D, E, F, G, H, K, N, T)

Reference number
ISO 6508-1:2005(E)
©
ISO 2005
ISO 6508-1:2005(E)
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ii © ISO 2005 – All rights reserved

ISO 6508-1:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Principle. 1
4 Symbols, abbreviated terms and designations . 1
5 Testing machine. 4
6 Test piece . 4
7 Procedure . 5
8 Uncertainty of the results . 6
9 Test report . 6
Annex A (normative) Conventional HR30Tm and HR15Tm test for thin products. 8
Annex B (normative) Minimum thickness of the test piece in relation to the Rockwell hardness. 9
Annex C (normative) Corrections to be added to Rockwell hardness values obtained on convex
cylindrical surfaces . 12
Annex D (normative) Corrections to be added to Rockwell hardness C scale values obtained on
spherical test surfaces of various diameters . 15
Annex E (informative) Procedure for periodic checking of the testing machine by the user . 16
Annex F (informative) Notes on diamond indenters. 17
Annex G (informative) Uncertainty of the measured hardness values. 18
Bibliography . 24

ISO 6508-1:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 6508-1 was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee
SC 3, Hardness testing.
This second edition cancels and replaces the first edition (ISO 6508-1:1999), which has been technically
revised.
ISO 6508 consists of the following parts, under the general title Metallic materials — Rockwell hardness test:
— Part 1: Test method (scales A, B, C, D, E, F, G, H, K, N, T)
— Part 2: Verification and calibration of testing machines (scales A, B, C, D, E, F, G, H, K, N, T)
— Part 3: Calibration of reference blocks (scales A, B, C, D, E, F, G, H, K, N, T)
iv © ISO 2005 – All rights reserved

ISO 6508-1:2005(E)
Introduction
The periodic checking of the testing machine described in informative Annex E is good metrological practice. It
is intended to make the annex normative in the next revision of this part of ISO 6508.

INTERNATIONAL STANDARD ISO 6508-1:2005(E)

Metallic materials — Rockwell hardness test —
Part 1:
Test method (scales A, B, C, D, E, F, G, H, K, N, T)
1 Scope
This part of ISO 6508 specifies the method for Rockwell and Rockwell superficial hardness tests (scales and
field of application according to Table 1) for metallic materials.
Attention is drawn to the fact that, in this part of ISO 6508, the use of hardmetal for ball indenters is
considered to be the standard type of Rockwell indenter ball. Steel indenter balls may be continued to be used
if specified in a product specification, or by special agreement.
NOTE 1 Attention is drawn to the fact that results obtained with hardmetal balls can be significantly different than when
using a steel ball. For specific materials and/or products, other specific International Standards apply (for instance
ISO 3738-1 and ISO 4498-1).
NOTE 2 For certain materials, the fields of application may be narrower than those indicated.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 6508-2:2005, Metallic materials — Rockwell hardness test — Part 2: Verification and calibration of testing
machines (scales A, B, C, D, E, F, G, H, K, N, T)
3 Principle
Forcing an indenter of specified size, shape and material into the surface of a test piece in two steps under
specified conditions (see Clause 7). Measuring the permanent depth h of indentation under preliminary test
force after removal of additional test force.
From the values of h and that of the two constants N and S (see Table 2), the Rockwell hardness is calculated
according to the formula:
h
Rockwell hardness=−N (1)
S
4 Symbols, abbreviated terms and designations
4.1 See Tables 1 and 2 and Figure 1.
ISO 6508-1:2005(E)
Table 1 — Rockwell scales
Rockwell Hardness Type of indenter Preliminary Additional Total test Field of application
hardness symbol test force test force force (Rockwell hardness test)
scale F F F
0 1
a
A HRA Diamond cone 98,07 N 490,3 N 588,4 N 20 HRA to 88 HRA

b
HRB Ball 1,587 5 mm 98,07 N 882,6 N 980,7 N 20 HRB to 100 HRB
B
c
C HRC Diamond cone 98,07 N 1,373 kN 1,471 kN 20 HRC to 70 HRC
D HRD Diamond cone 98,07 N 882,6 N 980,7 N 40 HRD to 77 HRD
E HRE Ball 3,175 mm 98,07 N 882,6 N 980,7 N 70 HRE to 100 HRE
F HRF Ball 1,587 5 mm 98,07 N 490,3 N 588,4 N 60 HRF to 100 HRF
G HRG Ball 1,587 5 mm 98,07 N 1,373 kN 1,471 kN 30 HRG to 94 HRG
H HRH Ball 3,175 mm 98,07 N 490,3 N 588,4 N 80 HRH to 100 HRH
K HRK Ball 3,175 mm 98,07 N 1,373 kN 1,471 kN 40 HRK to 100 HRK
15N HR15N Diamond cone 29,42 N 117,7 N 147,1 N 70 HR15N to 94 HR15N
30N HR30N Diamond cone 29,42 N 264,8 N 294,2 N 42 HR30N to 86 HR30N
45N HR45N Diamond cone 29,42 N 411,9 N 441,3 N 20 HR45N to 77 HR45N
15T HR15T Ball 1,587 5 mm 29,42 N 117,7 N 147,1 N 67 HR15T to 93 HR15T
30T HR30T Ball 1,587 5 mm 29,42 N 264,8 N 294,2 N 29 HR30T to 82 HR30T
45T HR45T Ball 1,587 5 mm 29,42 N 411,9 N 441,3 N 10 HR45T to 72 HR45T
a
The field of application can be extended to 94 HRA for testing carbides.
b
The field of application can be extended to 10 HRBW if specified in the product specification or by special agreement.
c
The field of application can be extended to 10 HRC if the indenter possesses the appropriate dimensions.
NOTE Indenter balls with diameter 6,350 mm and 12,70 mm may also be used, if specified in the product specification or by
special agreement.
2 © ISO 2005 – All rights reserved

ISO 6508-1:2005(E)
Table 2 — Symbols and abbreviated terms
Symbol/
Abbreviated Designation Unit
term
F
Preliminary test force N
F Additional test force N
F Total test force N
S Scale unit, specific to the scale mm
N Number, specific to the scale
h Permanent depth of indentation under preliminary test force after removal of additional test force mm
(permanent indentation depth)
HRA
h
Rockwell hardness=−100
0,002
HRC
HRD
HRB h
Rockwell hardness=−130
0,002
HRE
HRF
HRG
HRH
HRK
HRN
h
Rockwell hardness=−100
0,001
HRT
4.2 The following is an example of the designation of Rockwell hardness.
EXAMPLE
NOTE The numbers representing the test forces were originally based on units of kgf. For example, the test force of
30 kgf has been converted to 294,2 N.
ISO 6508-1:2005(E)
Key
1 Indentation depth by preliminary force F 5 Surface of specimen
2 Indentation depth by additional test force F 6 Reference plane for measurement
3 Elastic recovery just after removal of additional test force F 7 Position of indenter
4 Permanent indentation depth h
Figure 1 — Rockwell principle diagram
5 Testing machine
5.1 Testing machine, capable of applying predetermined forces as shown in Table 1 and in accordance
with ISO 6508-2.
5.2 Conical diamond indenter, in accordance with ISO 6508-2, with an angle of 120° and radius of
curvature at the tip of 0,2 mm.
5.3 Hardmetal ball indenter, in accordance with ISO 6508-2, with a diameter of 1,587 5 mm or 3,175 mm.
5.4 Measuring system, in accordance with ISO 6508-2.
NOTE A suggested procedure for periodic checks is given in Annex E. See also notes on diamond indenters in
Annex F.
6 Test piece
6.1 The test shall be carried out on a surface which is smooth and even, free from oxide scale, foreign
matter and, in particular, completely free from lubricants, unless specified otherwise in product or materials
standards. An exception is made for reactive metals, such as titanium, which might adhere to the indenter. In
such situations, a suitable lubricant such as kerosene may be used. The use of a lubricant shall be reported
on the test report.
6.2 Preparation shall be carried out in such a way that any alteration of the surface hardness due to
excessive heating or cold-working for example, is minimized. This shall be taken into account, particularly in
the case of low-depth indentations.
6.3 After the test, no deformation shall be visible on the surface of the test piece opposite the indentation,
except for HR30Tm (in this case, the test shall be performed in accordance with Annex A).
4 © ISO 2005 – All rights reserved

ISO 6508-1:2005(E)
The thickness of the test piece, or of the layer under test (minimum values given in Annex B), shall be at least
ten times the permanent indentation depth for cone indenters and fifteen times the permanent indentation
depth for ball indenters, unless it can be demonstrated that the use of a thinner test piece does not affect the
measured hardness value.
6.4 For tests on convex cylindrical surfaces and spherical surfaces, the corrections given in Annex C
(Tables C.1, C.2, C.3 or C.4) and in Annex D (Table D.1) shall be applied.
In the absence of corrections for tests on concave surfaces, tests on such surfaces should be the subject of a
special agreement.
7 Procedure
7.1 The test is normally carried out at ambient temperature within the limits of 10 °C to 35 °C. However,
because temperature variation may affect the results, users of the Rockwell test may choose to control the
temperature within a tighter range.
NOTE The temperature of the test material and the temperature of the hardness testing machine may effect the test
results; consequently users should ensure that the test temperature does not adversally affect the hardness measurement.
7.2 The test piece shall be placed on a rigid support and supported in such a manner that the surface to be
indented is in a plane normal to the axis of the indenter and the line of the indenting force, as well as to avoid
a displacement of the test piece. If a locking device is used, it should be used in accordance with Clause 3 of
ISO 6508-2:2005.
Before beginning a series of tests or when more than 24 h have elapsed since the last test, and after each
change, or removal and replacement, of the indenter or test piece support, it shall be ascertained that the
indenter and the test piece support are correctly mounted in the machine. The first two readings after such a
change has been made shall be disregarded.
Products of cylindrical shape shall be suitably supported, for example, on centering V-blocks of steel with a
Rockwell hardness of at least 60 HRC. Special attention shall be given to the correct seating, bearing and
alignment of the indenters, the test piece, the centering V-blocks and the specimen holder of the testing
machine, since any perpendicular misalignment may result in incorrect results.
7.3 Bring the indenter into contact with the test surface and apply the preliminary test force F without shock,
vibration or oscillation. The duration of the preliminary test force F shall not exceed 3 s.
NOTE For testing machines with electronic control, the application time of the preliminary test force (T ) and the
a
duration time of the preliminary test force (T ) are combined by the following formula:
pm
T = T /2 + T u 3 s (2)
p a pm
where
T is the total time of preliminary test force;
p
T is the application time of preliminary test force;
a
T is the duration time of preliminary test force.
pm
7.4 Set the measuring system to its datum position and, without shock, vibration or oscillation, increase the
force from F to F in not less than 1 s and not more than 8 s.
NOTE In normal practice, the duration from F to F is between 2 s and 3 s on a test piece of about 60 HRC. For the
Rockwell scales N and T, it is recommended that the duration is between 1 s and 1,5 s on a test piece of about 78 HR30N.
7.5 The total test force F shall be maintained for a duration of 4 s ± 2 s. Remove the additional test force F
and, while the preliminary test force F is maintained, after a short time stabilisation, the final reading shall be
made.
ISO 6508-1:2005(E)
As an exception for test materials exhibiting excessive plastic flow (indentation creep) during the application of
the total test force, special considerations may be necessary since the indenter will continue to penetrate.
When materials require the use of a total force duration that exceeds the 6 s allowed by the tolerances, this
requirement should he specified in the product specification. In these cases, the actual extended total force
duration used shall be reported following the test results (for example, 65 HRFW, 10 s).
7.6 The Rockwell hardness number is derived from the permanent indentation depth h using the formulas
given in Table 2 and is usually read directly from the measuring system. The derivation of the Rockwell
hardness number is illustrated in Figure 1.
7.7 Throughout the test, the apparatus shall be protected from shock or vibration.
7.8 The distance between the centres of two adjacent indentations shall be at least four times the diameter
of the indentation (but not less than 2 mm).
The distance from the centre of any indentation to an edge of the test piece shall be at least two and a half
times the diameter of the indentation (but not less than 1 mm).
8 Uncertainty of the results
A complete evaluation of the uncertainty should be done according to the Guide to the
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