SIST EN ISO 898-2:2022
(Main)Fasteners - Mechanical properties of fasteners made of carbon steel and alloy steel - Part 2: Nuts with specified property classes (ISO 898-2:2022)
Fasteners - Mechanical properties of fasteners made of carbon steel and alloy steel - Part 2: Nuts with specified property classes (ISO 898-2:2022)
This document specifies the mechanical and physical properties of nuts made of non-alloy steel or alloy
steel, when tested at the ambient temperature range of 10 °C to 35 °C.
This document applies to nuts:
— with ISO metric thread (see ISO 68-1),
— with diameter/pitch combinations according to ISO 261 and ISO 262,
— with coarse pitch thread M5 to M39, and fine pitch thread M8×1 to M39×3,
— with thread tolerances according to ISO 965-1, ISO 965-2 or ISO 965-5,
— with specified property classes 04, 05, 5, 6, 8, 10 and 12 including proof load,
— of three different nut styles (see 5.1): regular nuts (style 1), high nuts (style 2) and thin nuts (style 0),
— with a minimum outside diameter or width across flats s ≥ 1,45D,
— able to mate with bolts, screws and studs with property classes in accordance with ISO 898-1 (see
Annex B), and
— intended to be used in applications ranging from –50 °C to +150 °C, or up to +300 °C.
WARNING — Nuts conforming to the requirements of this document are tested at the ambient
temperature range of 10 °C to 35 °C and are used in applications ranging from –50 °C to +150 °C;
however, these nuts are also used outside this range and up to +300 °C for specific applications.
It is possible that they do not retain the specified mechanical and physical properties at lower
and/or elevated temperatures. Therefore, it is the responsibility of the user to determine the
appropriate choices based on the service environment conditions of the assembly (see also 7.1).
For additional specifications applicable to hot dip galvanized nuts, see ISO 10684.
For nuts designed for particular applications, see ISO/TR 16224.
This document does not specify requirements for functional properties such as:
— prevailing torque properties (see ISO 2320),
— torque/clamp force properties (see ISO 16047 for test method),
— weldability, or
— corrosion resistance.
Mechanische Verbindungselemente - Mechanische Eigenschaften von Verbindungselementen aus Kohlenstoffstahl und legiertem Stahl - Teil 2: Muttern mit festgelegten Festigkeitsklassen (ISO 898-2:2022)
Dieses Dokument legt die mechanischen und physikalischen Eigenschaften von Muttern aus unlegiertem Stahl und legiertem Stahl bei Prüfung bei Umgebungstemperatur im Bereich von 10 °C bis 35 °C fest:
Dieses Dokument ist anzuwenden für für Muttern:
— mit metrischem ISO Gewinde (siehe ISO 68 1),
— mit Durchmesser-Steigungskombinationen nach ISO 261 und ISO 262,
— mit Regelgewinde M5 bis M39 und Feingewinde M8×1 bis M39×3,
— mit Gewindetoleranzen nach ISO 965 1, ISO 965 2 oder ISO 965 5,
— mit festgelegten Festigkeitsklassen 04, 05, 5, 6, 8, 10 und 12, die die Prüfkraft einschließen,
— von drei verschiedenen Mutterntypen (siehe 5.1): normale Muttern (Typ 1), hohe Muttern (Typ 2) und niedrige Muttern (Typ 0),
— mit einem Mindestaußendurchmesser oder einer Mindestschlüsselweite s ≥ 1,45D.
— die mit Schrauben der Festigkeitsklassen nach ISO 898 1 gepaart werden können (siehe Anhang B), und
— die für Anwendungen im Bereich von −50 °C bis +150 °C oder bis zu +300 °C vorgesehen sind.
WARNUNG Muttern, die den Anforderungen dieses Dokuments entsprechen, werden im Umgebungstemperaturbereich von 10 °C bis 35 °C geprüft und für Anwendungen im Bereich von −50 °C bis +150 °C eingesetzt, allerdings werden diese Muttern auch außerhalb dieses Bereichs und bis zu +300 °C für spezielle Anwendungen eingesetzt. Es ist möglich, dass sie die festgelegten mechanischen und physikalischen Eigenschaften bei niedrigeren und/oder höheren Temperaturen nicht beibehalten. Daher liegt es in der Verantwortung des Anwenders, die geeignete Wahl auf der Grundlage der Betriebsumgebungsbedingungen der Verbindung zu treffen (siehe auch 7.1).
Zu zusätzlichen Festlegungen für feuerverzinkte Muttern siehe ISO 10684.
Zu Muttern, die für bestimmte Anwendungen ausgelegt sind, siehe ISO/TR 16224.
Dieses Dokument legt keine Anforderungen an Funktionseigenschaften fest, wie:
— Sicherungseigenschaften (siehe ISO 2320),
— Drehmoment/Vorspannkraft-Verhalten (siehe ISO 16047 für entsprechendes Prüfverfahren),
— Schweißbarkeit, oder
— Korrosionsbeständigkeit.
Fixations - Caractéristiques mécaniques des fixations en acier au carbone et en acier allié - Partie 2: Écrous de classes de qualité spécifiées (ISO 898-2:2022)
Le présent document spécifie les caractéristiques mécaniques et physiques des écrous en acier non allié ou acier allié, lorsqu’ils sont soumis à essai dans la plage de température ambiante de 10 °C à 35 °C.
Le présent document s’applique aux écrous:
— à filetage métrique ISO (voir l'ISO 68‑1),
— de combinaisons diamètre/pas selon l'ISO 261 et l'ISO 262,
— de diamètres de filetage M5 à M39 pour le pas gros, et M8×1 à M39×3 pour le pas fin,
— de tolérances de filetage selon l’ISO 965‑1, l’ISO 965‑2 ou l’ISO 965‑5,
— de classes de qualité spécifiées 04, 05, 5, 6, 8, 10 et 12, incluant la charge d’épreuve,
— de trois styles d’écrou différents (voir 5.1): écrous normaux (style 1), écrous hauts (style 2) et écrous bas (style 0),
— de diamètre extérieur minimal ou de surplat minimal s ≥ 1,45D,
— conçus pour être utilisés avec des vis, goujons et tiges filetées de classes de qualité conformes à l'ISO 898‑1 (voir l’Annexe B), et
— destinés à être utilisés pour des applications dans la plage de –50 °C à +150 °C, ou jusqu’à +300 °C.
AVERTISSEMENT — Les écrous conformes aux exigences du présent document sont soumis à essai dans la plage de température ambiante de 10 °C à 35 °C et sont utilisés pour des applications dans la plage de –50 °C à +150 °C; cependant, ces écrous sont également utilisés en dehors de cette plage et jusqu’à +300 °C pour des applications spécifiques. Il est possible qu'ils ne conservent pas les caractéristiques mécaniques et physiques spécifiées à des températures plus basses et/ou plus élevées. Par conséquent, il est de la responsabilité de l’utilisateur de déterminer les choix appropriés en fonction des conditions d’environnement de l’assemblage pour une application donnée (voir également 7.1).
Pour les spécifications supplémentaires applicables aux écrous galvanisés à chaud, voir l’ISO 10684.
Pour les écrous conçus pour des applications particulières, voir l’ISO/TR 16224.
Le présent document ne spécifie pas d’exigence pour des caractéristiques fonctionnelles telles que:
— les caractéristiques d'autofreinage (voir l’ISO 2320),
— les caractéristiques de couple/tension (voir l’ISO 16047 pour la méthode d'essai),
— la soudabilité, ou
— la résistance à la corrosion.
Vezni elementi - Mehanske lastnosti veznih elementov, narejenih iz ogljikovega jekla in jeklene zlitine - 2. del: Matice z določenimi razredi trdnosti (ISO 898-2:2022)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 898-2:2022
01-december-2022
Nadomešča:
SIST EN ISO 898-2:2012
Vezni elementi - Mehanske lastnosti veznih elementov, narejenih iz ogljikovega
jekla in jeklene zlitine - 2. del: Matice z določenimi razredi trdnosti (ISO 898-2:2022)
Fasteners - Mechanical properties of fasteners made of carbon steel and alloy steel -
Part 2: Nuts with specified property classes (ISO 898-2:2022)
Mechanische Verbindungselemente - Mechanische Eigenschaften von
Verbindungselementen aus Kohlenstoffstahl und legiertem Stahl - Teil 2: Muttern mit
festgelegten Festigkeitsklassen (ISO 898-2:2022)
Fixations - Caractéristiques mécaniques des fixations en acier au carbone et en acier
allié - Partie 2: Écrous de classes de qualité spécifiées (ISO 898-2:2022)
Ta slovenski standard je istoveten z: EN ISO 898-2:2022
ICS:
21.060.20 Matice Nuts
SIST EN ISO 898-2:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 898-2:2022
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SIST EN ISO 898-2:2022
EN ISO 898-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 21.060.20 Supersedes EN ISO 898-2:2012
English Version
Fasteners - Mechanical properties of fasteners made of
carbon steel and alloy steel - Part 2: Nuts with specified
property classes (ISO 898-2:2022)
Fixations - Caractéristiques mécaniques des fixations Mechanische Verbindungselemente - Mechanische
en acier au carbone et en acier allié - Partie 2: Écrous Eigenschaften von Verbindungselementen aus
de classes de qualité spécifiées (ISO 898-2:2022) Kohlenstoffstahl und legiertem Stahl - Teil 2: Muttern
mit festgelegten Festigkeitsklassen (ISO 898-2:2022)
This European Standard was approved by CEN on 9 September 2022.
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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 898-2:2022 E
worldwide for CEN national Members.
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SIST EN ISO 898-2:2022
EN ISO 898-2:2022 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 898-2:2022
EN ISO 898-2:2022 (E)
European foreword
This document (EN ISO 898-2:2022) has been prepared by Technical Committee ISO/TC 2 "Fasteners"
in collaboration with Technical Committee CEN/TC 185 “Fasteners” the secretariat of which is held by
BSI.
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 April 2023, and conflicting national standards shall be
withdrawn at the latest by April 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 898-2:2012.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 898-2:2022 has been approved by CEN as EN ISO 898-2:2022 without any modification.
3
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SIST EN ISO 898-2:2022
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SIST EN ISO 898-2:2022
INTERNATIONAL ISO
STANDARD 898-2
Fourth edition
2022-09
Fasteners — Mechanical properties
of fasteners made of carbon steel and
alloy steel —
Part 2:
Nuts with specified property classes
Fixations — Caractéristiques mécaniques des fixations en acier au
carbone et en acier allié —
Partie 2: Écrous de classes de qualité spécifiées
Reference number
ISO 898-2:2022(E)
© ISO 2022
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SIST EN ISO 898-2:2022
ISO 898-2:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
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© ISO 2022 – All rights reserved
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SIST EN ISO 898-2:2022
ISO 898-2:2022(E)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Symbols . 2
5 Designation systems .3
5.1 Nut styles . 3
5.2 Property classes . 3
5.2.1 Regular nuts (style 1) and high nuts (style 2) . 3
5.2.2 Thin nuts (style 0) . 4
6 Design of bolt and nut assemblies . 4
7 Material, heat treatment, chemical composition and steel microstructure .4
7.1 General . 4
7.2 Heat treatment. 5
7.3 Chemical composition . 5
7.4 Steel microstructure . 7
7.4.1 Non-quenched and tempered nuts . 7
7.4.2 Quenched and tempered nuts . 7
8 Mechanical and physical properties . 7
8.1 General . 7
8.2 Proof load . 8
8.3 Hardness . 9
8.4 Surface integrity . 11
9 Inspection .11
9.1 Manufacturer's inspection . 11
9.2 Supplier's inspection . 11
9.3 Purchaser's inspection . 11
9.4 Delivery of test results . 12
10 Test methods .12
10.1 Proof load test .12
10.1.1 General .12
10.1.2 Applicability .12
10.1.3 Apparatus . 12
10.1.4 Testing device .12
10.1.5 Test procedure. 13
10.1.6 Test results and requirements . 14
10.2 Hardness tests . 14
10.2.1 General . 14
10.2.2 Applicability . 14
10.2.3 Test methods . 14
10.2.4 Test procedures for routine inspection . 14
10.2.5 Hardness determined in the thread . 16
10.2.6 Hardness determined in the core . 17
10.2.7 Uniformity of hardness for quenched and tempered nuts (QT) . 18
10.2.8 Requirements for non-quenched and tempered nuts (NQT) . 18
10.2.9 Requirements for quenched and tempered nuts (QT) . 18
10.3 Steel microstructure . 19
10.3.1 General . 19
10.3.2 Applicability . 19
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© ISO 2022 – All rights reserved
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SIST EN ISO 898-2:2022
ISO 898-2:2022(E)
10.3.3 Test method . 19
10.3.4 Test results and requirements . 19
10.4 Retempering test . 19
10.4.1 General . 19
10.4.2 Test procedure. 19
10.4.3 Test results and requirements . 20
10.5 Surface discontinuity inspection . 20
11 Marking and labelling .20
11.1 General requirements . 20
11.2 Property class marking symbols for nuts with full loadability . 20
11.3 Property class marking symbols for nuts with reduced loadability . 21
11.4 Manufacturer’s identification mark. 21
11.5 Nut marking . 21
11.6 Marking of the packages (labelling) . 23
Annex A (normative) Thread dimensions of the test mandrel .25
Annex B (informative) Design principles for nuts.27
Annex C (informative) Stress under proof load, S .29
P
Bibliography .31
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© ISO 2022 – All rights reserved
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SIST EN ISO 898-2:2022
ISO 898-2:2022(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 2, Fasteners, Subcommittee SC 12,
Fasteners with metric internal thread, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 185, Fasteners, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 898-2:2012) which has been technically
revised.
The main changes are as follows:
— property class 9 has been deleted completely, and nuts with fine pitch thread and property class 5
have been deleted (see Introduction);
— nuts with fine pitch thread in style 2 and property class 12 have been added for diameters 18 mm to
39 mm (see Tables 4, 6 and 10);
— styles have been more precisely specified for standard hexagon nuts according to their minimum
height, and styles have been specified for other nuts according to their minimum design thread
height (see 5.1);
— additional statements for thin nuts and jam nuts have been added (see Clause 6);
— additional statements for hot dip galvanized nuts have been added by referencing ISO 10684;
— in relation to material, heat treatment and steel microstructure (see Clause 7):
— the minimum carbon content has been added (see Tables 3 and 4),
— the minimum manganese content has been specified to 0,25 % for all Non-Quenched and
Tempered nuts (NQT) and has been raised to 0,45 % for all Quenched and Tempered nuts (QT)
(see Tables 3 and 4),
— the table footnote for free cutting steel has been reworked (see Tables 3 and 4),
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© ISO 2022 – All rights reserved
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SIST EN ISO 898-2:2022
ISO 898-2:2022(E)
— the minimum tempering temperature has been added for QT nuts (see Tables 3 and 4), and a
reference retempering test has been added (see 10.4),
— for nuts that may optionally be quenched and tempered at the manufacturer’s discretion,
detailed specifications have been added (see 7.2),
— specifications for steel microstructure have been added for NQT and QT nuts (see 7.4.1, 7.4.2
and 10.3);
— in relation to proof load:
— the proof load values for nuts with coarse pitch thread and property classes 6 and 8 have been
raised for sizes M27 to M39 (see Introduction, Table 5, and Annex C),
— the maximum hole diameter for the grip has been corrected for diameters 5 mm and 6 mm (see
Table 11), and reference to additional proof load specifications has been added for prevailing
torque nuts (see 10.1);
— in relation to hardness:
— the reference Vickers hardness values have been recalculated, and conversion into Brinell and
Rockwell hardness has been adjusted (see Introduction and 8.3),
— hardness determined on the bearing surface (see 10.2.4 a) and hardness determined in the
transverse section at mid-height of the nut (see 10.2.4 b) have been added for routine inspection,
— the test method for hardness determined in the thread has been improved and the test force has
been specified according to the pitch dimension (see 10.2.5),
— for QT nuts, the test methods for hardness in the core (see 10.2.6) and uniformity of hardness
(see 10.2.7) have been added,
— requirements for hardness have been clarified (see 10.2.8 and 10.2.9);
— inspection documents have been referenced in accordance with ISO 16228 for fasteners (see 9.4);
— marking and labelling have been revised, and all nuts conforming to this document are to be marked
whatever their shape (see Clause 11);
— Annex B, Design principles for nuts, has been improved;
— Annex C, Nominal stress under proof load, has been added.
A list of all parts in the ISO 898 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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© ISO 2022 – All rights reserved
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SIST EN ISO 898-2:2022
ISO 898-2:2022(E)
Introduction
ISO 898, the basic standard for fasteners with ISO metric thread made of carbon steel and alloy steel,
was developed in several parts, and includes diameters 5 mm to 39 mm only for nuts. Property classes
are specified in the ISO 898 series in relation to materials and mechanical properties, so that nuts in
accordance with ISO 898-2 are matching with bolts, screws and studs specified in ISO 898-1 and with
flat washers specified in ISO 898-3, as necessary, in order to design suitable assemblies for a given
application.
More parts are under development for bolts, screws, studs and nuts with sizes above 39 mm.
The nuts specified in this document result from the adequate combination of nut heights (regular,
style 1 – high, style 2 – thin, style 0), diameter ranges, coarse or fine pitch thread, and property classes
in relation to heat treatment (Non-Quenched and Tempered = NQT, or Quenched and Tempered = QT).
These combinations are based on bolt/nut compatibility, manufacturing processes and market needs.
If other combinations are needed, e.g. for nuts designed for particular applications, see ISO/TR 16224.
In order to assure the necessary material strength in relation to property classes:
— Quenched and Tempered nuts (QT) are specified with a minimum carbon content and a minimum
tempering temperature, and are characterized by a homogeneous martensitic structure;
— Non-Quenched and Tempered nuts (NQT) are also specified with a minimum carbon content but are
characterized by a non-quenched microstructure.
Some property classes (in relation to nut style, diameter and coarse or fine pitch thread) specified as
NQT may be optionally quenched and tempered as specified in 7.2, and in this case all requirements for
QT nuts apply.
For fully loadable non-standard nuts which are to meet the requirements of this document, the relevant
style 1 or style 2 is assigned in relation to their minimum design thread height.
Nut loadability is primarily checked by proof load. For nuts with coarse pitch thread and property
classes 6 and 8, proof load values have been raised for sizes M27 to M39 due to the latest calculations of
[20] [21]
Masaya Hagiwara in accordance with the Alexander's theory , see ISO/TR 16224. For those nuts
it was necessary to develop full strength in relation to the mating bolts, screws and studs specified in
ISO 898-1, the difference between the proof loads of ISO 898-2:2012 and the recalculated values being
more than 5 % (see Annex C).
The Vickers hardness values specified for each individual group (consisting of property class, style,
diameter range and pitch) have been chosen according to the same latest calculations, but adjusted to
conventional figures taken over from the former versions of Parts 2 and 6 which were merged in 2012.
ISO 18265 presents no hardness to tensile strength correlation for steel in work hardened condition,
which is typical for cold forged high volume NQT nuts: therefore, minimum hardness is just informative
for NQT nuts and does not constitute a criterion in case of dispute. The maximum hardness of 334 HV is
specified in order to prevent unexpected manufacturing processes which can lead to brittle behaviour
of the NQT nuts: this limit is therefore mandatory and valid in case of dispute. However, it should be
noted that work hardening is usually not severe enough to reach 302 HV when typical material and
forging processes are used; nevertheless, inappropriate hardness testing or scattering due to just local
properties is also covered by this specified limit of 334 HV.
Due to missing or decreasing market needs, nuts of property class 5 with fine pitch thread in style 1
and nuts of property class 9 were deleted (property class 5 or 9 can be substituted by property class 6
or 10 respectively).
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© ISO 2022 – All rights reserved
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SIST EN ISO 898-2:2022
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SIST EN ISO 898-2:2022
INTERNATIONAL STANDARD ISO 898-2:2022(E)
Fasteners — Mechanical properties of fasteners made of
carbon steel and alloy steel —
Part 2:
Nuts with specified property classes
1 Scope
This document specifies the mechanical and physical properties of nuts made of non-alloy steel or alloy
steel, when tested
...
SLOVENSKI STANDARD
oSIST prEN ISO 898-2:2021
01-november-2021
Vezni elementi - Mehanske lastnosti veznih elementov, narejenih iz ogljikovega
jekla in jeklene zlitine - 2. del: Matice z določenimi razredi trdnosti (ISO/DIS 898-
2:2021)
Fasteners - Mechanical properties of fasteners made of carbon steel and alloy steel -
Part 2: Nuts with specified property classes (ISO/DIS 898-2:2021)
Mechanische Verbindungselemente - Mechanische Eigenschaften von
Verbindungselementen aus Kohlenstoffstahl und legiertem Stahl - Teil 2: Muttern mit
festgelegten Festigkeitsklassen (ISO/DIS 898-2:2021)
Fixations - Caractéristiques mécaniques des fixations en acier au carbone et en acier
allié - Partie 2: Écrous de classes de qualité spécifiées (ISO/DIS 898-2:2021)
Ta slovenski standard je istoveten z: prEN ISO 898-2
ICS:
21.060.20 Matice Nuts
oSIST prEN ISO 898-2:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 898-2:2021
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oSIST prEN ISO 898-2:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 898-2
ISO/TC 2/SC 12 Secretariat: DIN
Voting begins on: Voting terminates on:
2021-08-30 2021-11-22
Fasteners — Mechanical properties of fasteners made of
carbon steel and alloy steel —
Part 2:
Nuts with specified property classes
Fixations — Caractéristiques mécaniques des fixations en acier au carbone et en acier allié —
Partie 2: Écrous de classes de qualité spécifiées
ICS: 21.060.20
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
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ISO/DIS 898-2:2021(E)
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oSIST prEN ISO 898-2:2021
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Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Symbols . 2
5 Designation systems . 3
5.1 Nut styles . 3
5.2 Property classes . 3
5.2.1 Regular nuts (style 1) and high nuts (style 2) . 3
5.2.2 Thin nuts (style 0) . 4
6 Design of bolt and nut assemblies . 4
7 Material, heat treatment, chemical composition and steel microstructure .4
7.1 General . 4
7.2 Heat treatment . 5
7.3 Chemical composition . 5
7.4 Steel microstructure . 7
7.4.1 Non-quenched and tempered nuts . 7
7.4.2 Quenched and tempered nuts . 7
8 Mechanical and physical properties . 7
8.1 General . 7
8.2 Proof load . 7
8.3 Hardness . 8
8.4 Surface integrity.10
9 Inspection .10
9.1 Manufacturer's inspection .10
9.2 Supplier's inspection .10
9.3 Purchaser's inspection .10
9.4 Delivery of test results .11
10 Test methods .11
10.1 Proof load test .11
10.1.1 General.11
10.1.2 Applicability .11
10.1.3 Apparatus .11
10.1.4 Testing device .11
10.1.5 Test procedure .12
10.1.6 Test results and requirements .13
10.2 Hardness tests .13
10.2.1 General.13
10.2.2 Applicability .13
10.2.3 Test methods .13
10.2.4 Test procedures for routine inspection .14
10.2.5 Hardness determined in the thread .15
10.2.6 Hardness determined in the core .16
10.2.7 Uniformity of hardness for quenched and tempered nuts (QT nuts) .17
10.2.8 Requirements for quenched and tempered nuts (QT nuts).17
10.2.9 Requirements for non-quenched and tempered nuts (NQT nuts) .17
10.3 Steel microstructure .17
10.3.1 General.17
10.3.2 Applicability .17
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10.3.3 Test method .17
10.3.4 Test results and requirements .18
10.4 Retempering test .18
10.4.1 General.18
10.4.2 Test procedure .18
10.4.3 Test results and requirements .18
10.5 Surface discontinuity inspection .18
11 Marking and labelling .18
11.1 General requirements .18
11.2 Property class marking symbols for nuts with full loadability .19
11.3 Property class marking symbols for nuts with reduced loadability .19
11.4 Manufacturer’s identification mark .20
11.5 Nut marking .20
11.6 Marking of the packages (labelling) .22
Annex A (normative) Thread dimensions of the test mandrel .23
Annex B (informative) Design principles for nuts .25
Annex C (informative) Nominal stress under proof load, S .27
P
Bibliography .29
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oSIST prEN ISO 898-2:2021
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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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/ iso/ foreword .html.
ISO 898-2 was prepared by Technical Committee ISO/TC 2, Fasteners, Subcommittee SC 12, Fasteners
with metric internal thread.
This fourth edition cancels and replaces the third edition (ISO 898-2:2012) which has been technically
revised.
The main changes compared to the previous edition are as follows:
— property class 9 has been deleted completely, and nuts with fine pitch thread and property class 5
have been deleted (see Introduction);
— nuts with fine pitch thread in style 2 and property class 12 have been added for diameters 18 mm to
39 mm (see Tables 4, 6 and 10);
— styles have been more precisely defined for standard hexagon nuts according to their minimum
height, and styles have been specified for other nuts according to their minimum design thread
height (see 5.1);
— additional statements for thin nuts and jam nuts have been added (see Clause 6);
— additional statements for hot dip galvanized nuts have been added by referencing ISO 10684;
— in relation to material, heat treatment and steel microstructure (see Clause 7):
• the minimum carbon content has been added (see Tables 3 and 4),
• the minimum manganese content has been specified to 0,25 % for all Non-Quenched and
Tempered nuts (NQT) and has been raised to 0,45 % for all Quenched and Tempered nuts (QT)
(see Tables 3 and 4),
• the footnote for free cutting steel has been reworked (see Tables 3 and 4),
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• the minimum tempering temperature has been added for QT nuts (see Tables 3 and 4), and a
reference retempering test has been added (see 10.4),
• for nuts that may optionally be quenched and tempered at the manufacturer’s discretion,
detailed specifications have been added (see 7.2),
• specifications for steel microstructure have been added for NQT and QT nuts (see 7.4.1, 7.4.2
and 10.3);
— in relation to proof load:
• the proof load values for nuts with coarse pitch thread and property classes 6 and 8 have been
raised for sizes M27 to M39 (see Introduction, Table 5 and Annex C),
• the maximum hole diameter for the grip has been corrected for diameters 5 mm and 6 mm (see
Table 11), and reference to additional proof load specifications have been added for prevailing
torque nuts (see 10.1);
— in relation to hardness:
• the reference Vickers hardness values have been recalculated, and conversion into Brinell and
Rockwell hardness has been improved (see Introduction and 8.3),
• hardness determined on the bearing surface (see 10.2.4 a) and hardness determined in the
transverse section at mid-height of the nut (see 10.2.4 b) have been added for routine inspection
only;
• the test method for hardness determined in the thread has been improved and the reference
test force has been specified according to the pitch dimension (see 10.2.5),
• for QT nuts, the test methods for hardness in the core (see 10.2.6) and uniformity of hardness
(see 10.2.7) have been added,
• requirements for hardness have been improved (see 10.2.8 and 10.2.9);
— inspection documents have been referenced in accordance with ISO 16228 for fasteners (see 9.4);
— marking and labelling have been improved, and all nuts conforming to this document are to be
marked whatever their shape (see Clause 11);
— Annex B, Design principles for nuts, has been improved;
— Annex C, Nominal stress under proof load, has been added.
More detailed background for the main technical improvements is given in Introduction.
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Introduction
ISO 898, the basic standard for fasteners with ISO metric thread made of carbon steel and alloy steel,
was developed in several parts for diameters 5 mm to 39 mm. Property classes are specified in the
ISO 898 series in relation to materials and mechanical properties, so that nuts in accordance with
ISO 898-2 are matching with bolts, screws and studs specified in ISO 898-1 and with flat washers
specified in ISO 898-3, as necessary, in order to design suiTable assemblies for a given application.
More parts will be developed in the future for bolts, screws, studs and nuts with sizes above 39 mm.
In order to assure the necessary material strength in relation to property classes:
— Quenched and Tempered nuts (QT) are specified with a minimum carbon content and a minimum
tempering temperature, are characterized by a homogeneous martensitic structure;
— Non-Quenched and Tempered nuts (NQT) are also specified with a minimum carbon content but are
characterized by a non-quenched microstructure.
Some property classes (in relation to nut style, diameter and coarse or fine pitch thread) specified as
NQT may be optionally quenched and tempered as specified in 7.2, and in this case all requirements for
QT nuts apply.
For fully loadable non-standard nuts which are to meet the requirements of this document, the relevant
style 1 or style 2 is assigned in relation to their minimum design thread height.
Nut loadability is primarily checked by proof load. For nuts with coarse pitch thread and property
classes 6 and 8, proof load values have been raised for sizes M27 to M39 due to the latest calculations
of Masaya Hagiwara [20] in accordance with the Alexander's theory [21], see ISO/TR 16224. For those
nuts it was necessary to develop full strength in relation to the mating bolts, screws and studs specified
in ISO 898-1, the difference between the proof loads of ISO 898-2:2012 and the recalculated values
being more than 5 % (see Annex C).
The Vickers hardness values specified for each individual group (consisting of property class, style,
pitch and diameter ranges) have been chosen according to the same latest calculations, but adjusted to
conventional figures taken over from the former versions of Parts 2 and 6 which were merged in 2012.
ISO 18265 presents no hardness to tensile strength correlation for steel in work hardened condition,
which is typical for cold forged high volume NQT nuts: therefore, minimum hardness is just informative
for NQT nuts and does not constitute a criterion in case of dispute. The maximum hardness of 334 HV
is specified in order to prevent unexpected manufacturing processes which can lead to brittle behavior
of the NQT nuts: this limit is therefore mandatory and valid in case of dispute. However, it should be
noted that work hardening is usually not severe enough to reach 302 HV when typical material and
forging processes are used; nevertheless, inappropriate hardness testing or scattering due to just local
properties is also covered by this specified limit of 334 HV.
Due to missing or decreasing market needs, nuts of property class 5 with fine pitch thread in style 1
and nuts of property class 9 with coarse pitch thread in style 2 were deleted (property class 5 or 9 can
be substituted by property class 6 or 10 respectively).
Nuts of property class 10 with fine pitch thread in style 1 for diameters 18 mm to 39 mm were deleted
but though, nuts of property class 12 with fine pitch thread in style 2 have been added for diameters
18 mm to 39 mm.
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oSIST prEN ISO 898-2:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 898-2:2021(E)
Fasteners — Mechanical properties of fasteners made of
carbon steel and alloy steel —
Part 2:
Nuts with specified property classes
1 Scope
This document specifies the mechanical and physical properties of nuts made of non-alloy steel or alloy
steel, for three different nut styles in accordance with 5.1:
— regular nuts (style 1),
— high nuts (style 2),
— thin nuts (style 0),
in combination with:
— coarse pitch thread M5 ≤ D ≤ M39, and fine pitch thread 8 mm ≤ D ≤ 39 mm,
— specified property classes 04, 05, 5, 6, 8, 10 and 12 including proof loads,
and able to be mated with bolts, screws and studs with property classes in accordance with ISO 898-1.
These combinations are based on bolt/nut compatibility, manufacturing processes and market needs.
If other combinations are needed, e.g. for nuts designed for particular applications, see ISO/TR 16224.
Nuts conforming to the requirements of this document are tested at the ambient temperature range of
10 °C to 35 °C. It is possible that they do not retain the specified mechanical and physical properties at
elevated and/or lower temperatures.
NOTE 1 Nuts conforming to the requirements of this document are used in applications ranging from –50 °C to
+150 °C, however these nuts are also used outside this range and up to +300 °C for specific applications. It is the
responsibility of the user to determine the appropriate choice, and consulting an experienced fastener materials
expert is recommended outside the range of –50 °C to +150 °C (several factors need to be taken into account,
e.g. steel composition, duration of exposure at elevated or low temperature, the effect of the temperature on the
fastener mechanical properties and clamped parts).
NOTE 2 Information for the selection and application of steels for use at lower and elevated temperatures is
given for instance in EN 10269, ASTM A320/A320M and ASTM A194/A194M.
This document applies to the nuts specified above, with:
— triangular ISO metric thread in accordance with ISO 68-1,
— diameter/pitch combinations in accordance with ISO 261 and ISO 262,
— thread tolerances in accordance with ISO 965-1, ISO 965-2 or ISO 965-5, and
— minimum outside diameter or width across flats s ≥ 1,45D (see Annex B).
For hot dip galvanized nuts, additional requirements are specified in ISO 10684.
This document does not specify requirements for functional properties such as:
— prevailing torque properties (see ISO 2320),
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— torque/clamp force properties (see ISO 16047 for test method),
— weldability, or
— corrosion resistance.
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 1891-4, Fasteners — Vocabulary — Part 4: Control, inspection, delivery, acceptance and quality
ISO 2320, Fasteners — Prevailing torque steel nuts — Functional properties
ISO 6157-2, Fasteners — Surface discontinuities — Part 2: Nuts
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 10684, Fasteners — Hot dip galvanized coatings
ISO 16228, Fasteners — Types of inspection documents
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
4 Symbols
For the purposes of this document, the following symbols apply.
D nominal thread diameter of the nut (basic major diamete
...
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