SIST EN ISO 3506-4:2025
(Main)Fasteners - Mechanical properties of corrosion-resistant stainless steel fasteners - Part 4: Tapping screws with specified grades and hardness classes (ISO 3506-4:2025)
Fasteners - Mechanical properties of corrosion-resistant stainless steel fasteners - Part 4: Tapping screws with specified grades and hardness classes (ISO 3506-4:2025)
This document specifies the mechanical and physical properties of tapping screws made of corrosion resistant austenitic, martensitic, ferritic and duplex stainless steels, with specified grades and hardness classes.
ISO 3506-6 provides general rules and additional technical information on suitable stainless steels and their properties (detailed properties of stainless steel grades, corrosion behaviour with regards to pitting, crevice and intergranular corrosion, magnetic properties, etc.).
WARNING — Tapping screws 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 –20 °C to +150 °C. 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 service environment conditions of the assembly (see also Clauses 5 and 6).
This document applies to tapping screws with threads ST2,2 to ST8, in accordance with ISO 1478.
This document does not apply to tapping screws with special properties, such as weldability.
Mechanische Verbindungselemente - Mechanische Eigenschaften von Verbindungselementen aus nichtrostenden Stählen - Teil 4: Blechschrauben mit festgelegten Stahlsorten und Härteklassen (ISO 3506-4:2025)
Dieses Dokument legt die mechanischen und physikalischen Eigenschaften von Blechschrauben aus nichtrostenden, korrosionsbeständigen austenitischen, martensitischen, ferritischen Stählen und Duplex-Stählen mit festgelegten Stahlsorten und Härteklassen fest.
WARNUNG — Blechschrauben, die den Anforderungen dieses Dokuments entsprechen, werden in einem Ugebungstemperaturbereich von 10 °C bis 35 °C geprüft und in einem Anwendungsbereich von −20 °C bis +150 °C eingesetzt. Eventuell ändern sich die festgelegten mechanischen und physikalischen Eigenschaften bei niedrigeren und/oder höheren Temperaturen. Es liegt daher in der Verantwortung des Anwenders, auf der Grundlage der Betriebsumgebungsbedingungen der Baugruppe die geeignete Auswahl zu treffen (siehe auch Abschnitt 5 und Abschnitt 6).
Dieses Dokument gilt für Blechschrauben mit Gewinden ST2,2 bis ST8, nach ISO 1478.
Dieses Dokument gilt nicht für Blechschrauben mit besonderen Eigenschaften, wie z. B. die Schweißbarkeit.
Fixations - Caractéristiques mécaniques des fixations en acier inoxydable résistant à la corrosion - Partie 4: Vis à tôle de grades et classes de dureté spécifiées (ISO 3506-4:2025)
Le présent document spécifie les caractéristiques mécaniques et physiques des vis à tôle en aciers inoxydables austénitiques, martensitiques, ferritiques et duplex résistant à la corrosion, de grades et classes de dureté spécifiées.
L’ISO 3506-6 fournit des règles générales et des informations techniques supplémentaires sur les aciers inoxydables appropriés et leurs propriétés (propriétés détaillées des grades d’acier inoxydable, comportement à la corrosion par piqûres, corrosion caverneuse et intergranulaire, magnétisme, etc.).
AVERTISSEMENT — Les vis à tôle conformes aux exigences du présent document sont soumises à essai dans la plage de température ambiante de 10 °C à 35 °C et sont utilisées dans des applications de −20 °C à +150 °C. Elles peuvent ne pas conserver les caractéristiques mécaniques et physiques spécifiées à des températures basses et/ou élevées. Par conséquent, il est de la responsabilité de l’utilisateur de déterminer les choix appropriés en fonction des conditions de l’environnement d’utilisation de l’assemblage (voir également les Articles 5 et 6).
Le présent document s’applique aux vis à tôle de filetage ST2,2 à ST8, conformément à l’ISO 1478.
Le présent document ne s’applique pas aux vis à tôle possédant des caractéristiques particulières telles que la soudabilité.
Vezni elementi - Mehanske lastnosti veznih elementov iz korozijsko odpornega nerjavnega jekla - 4. del: Pločevinski vijaki z določenimi razredi in razredi trdnosti (ISO 3506-4:2025)
Ta del ISO 3506 določa mehanske lastnosti pločevinskih vijakov, narejenih iz avstenitnih, martenzitnih in feritnih vrst nerjavnega jekla, odpornega proti koroziji, pri preskušanju v območju okoljske temperature med 10 °C in 35 °C. Lastnosti se spreminjajo glede na višje ali nižje temperature.
Velja za pločevinske vijake z navoji od ST2,2 do vključno ST8, v skladu z ISO 1478.
Ne velja za vijake s posebnimi lastnostmi, kot je varivost.
OPOMBA: Sistem označevanja v tem delu ISO 3506 se lahko uporablja za velikosti zunaj omejitev, podanih v tej točki (npr. d ST8), če so izpolnjene veljavne mehanske in fizikalne zahteve razredov trdote.
Ta del ISO 3506 ne opredeljuje odpornosti proti koroziji ali oksidaciji v nekaterih okoljih. Nekateri podatki o materialih za določena okolja so kljub temu navedeni v dodatku C. Za opredelitve korozije in odpornosti proti koroziji glej ISO 8044. Namen tega dela ISO 3506 je razvrstitev pločevinskih vijakov iz nerjavnega jekla, odpornega proti koroziji, v razrede trdote.
O zmogljivostih, povezanih s korozijo in oksidacijo, ter mehanskih lastnostih za uporabo pri povišanih temperaturah ali temperaturah pod nič se lahko dogovorita uporabnik in proizvajalec za vsak posamezen primer. Dodatek D prikazuje, kako je tveganje za interkristalno korozijo pri povišanih temperaturah odvisno od vsebnosti ogljika.
Vsi vezni elementi iz avstenitnega nerjavnega jekla so v nežarjenem stanju običajno nemagnetni; po hladni obdelavi so nekatere magnetne lastnosti očitne (glej dodatek E).
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2025
Vezni elementi - Mehanske lastnosti veznih elementov iz korozijsko odpornega
nerjavnega jekla - 4. del: Pločevinski vijaki z določenimi razredi in razredi trdnosti
(ISO 3506-4:2025)
Fasteners - Mechanical properties of corrosion-resistant stainless steel fasteners - Part
4: Tapping screws with specified grades and hardness classes (ISO 3506-4:2025)
Mechanische Verbindungselemente - Mechanische Eigenschaften von
Verbindungselementen aus nichtrostenden Stählen - Teil 4: Blechschrauben mit
festgelegten Stahlsorten und Härteklassen (ISO 3506-4:2025)
Fixations - Caractéristiques mécaniques des fixations en acier inoxydable résistant à la
corrosion - Partie 4: Vis à tôle de grades et classes de dureté spécifiées (ISO 3506-
4:2025)
Ta slovenski standard je istoveten z: EN ISO 3506-4:2025
ICS:
21.060.10 Sorniki, vijaki, stebelni vijaki Bolts, screws, studs
77.140.20 Visokokakovostna jekla Stainless steels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 3506-4
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2025
EUROPÄISCHE NORM
ICS 21.060.10 Supersedes EN ISO 3506-4:2009
English Version
Fasteners - Mechanical properties of corrosion-resistant
stainless steel fasteners - Part 4: Tapping screws with
specified grades and hardness classes (ISO 3506-4:2025)
Fixations - Caractéristiques mécaniques des fixations Mechanische Verbindungselemente - Mechanische
en acier inoxydable résistant à la corrosion - Partie 4: Eigenschaften von Verbindungselementen aus
Vis à tôle de grades et classes de dureté spécifiées (ISO nichtrostenden Stählen - Teil 4: Blechschrauben mit
3506-4:2025) festgelegten Stahlsorten und Härteklassen (ISO 3506-
4:2025)
This European Standard was approved by CEN on 19 January 2025.
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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 3506-4:2025 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 3506-4:2025) 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 July 2025, and conflicting national standards shall be
withdrawn at the latest by July 2025.
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 3506-4:2009.
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 3506-4:2025 has been approved by CEN as EN ISO 3506-4:2025 without any
modification.
International
Standard
ISO 3506-4
Third edition
Fasteners — Mechanical properties
2025-01
of corrosion-resistant stainless steel
fasteners —
Part 4:
Tapping screws with specified
grades and hardness classes
Fixations — Caractéristiques mécaniques des fixations en acier
inoxydable résistant à la corrosion —
Partie 4: Vis à tôle de grades et classes de dureté spécifiés
Reference number
ISO 3506-4:2025(en) © ISO 2025
ISO 3506-4:2025(en)
© ISO 2025
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
ii
ISO 3506-4:2025(en)
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Designation system for stainless steel grades and hardness classes . 2
4.1 General .2
4.2 Designation of stainless steel grades (first block) .4
4.3 Designation of hardness classes (second block) .4
5 Materials . 4
5.1 Chemical composition .4
5.2 Heat treatment for martensitic stainless steel tapping screws .5
5.3 Surface condition (finish and/or coating) .5
5.4 Corrosion resistance .6
5.5 Magnetic properties .6
6 Requirements for mechanical, physical and functional properties . 6
6.1 General .6
6.2 Surface hardness for martensitic grades .6
6.3 Core hardness .7
6.4 Thread forming ability .7
6.5 Torsional strength .7
7 Inspection . 8
7.1 Manufacturer’s inspection .8
7.2 Supplier’s inspection .8
7.3 Purchaser’s inspection .8
7.4 Delivery of test results .8
8 Test methods . 8
8.1 General .8
8.2 Hardness test .9
8.2.1 General .9
8.2.2 Surface hardness test .9
8.2.3 Core hardness test .9
8.2.4 Test results and requirements .9
8.3 Drive test .10
8.4 Torsional test.10
9 Marking and labelling .11
9.1 General .11
9.2 Marking on the tapping screws . 12
9.3 Labelling of the packages . 12
Bibliography .13
iii
ISO 3506-4:2025(en)
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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, 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 third edition cancels and replaces the second edition (ISO 3506-4:2009), which has been technically
revised.
The main changes are as follows:
— annexes common to several parts of the ISO 3506 series have been withdrawn from this document and
are now included in the new ISO 3506-6 which is to be used with this document;
— austenitic stainless steel of grade A8 and duplex (austenitic-ferritic) stainless steels of grades D2 to D8
for hardness classes 20H, 25H and 30H have been added (see Figure 1);
— operational temperature ranges have been clarified (see Clause 1);
— terms and definitions have been added (see Clause 3);
— wording for surface conditions and corrosion resistance have been improved (see 5.3 and 5.4);
— manufacturer’s, supplier’s and purchaser’s inspections have been added (see Clause 7);
— applicability of test methods has been added, and hardness test, torsional test and drive test methods
have been improved (see Clause 8);
— marking and labelling have been improved (see Clause 9);
— structure and content of this document have been brought in line with other parts of ISO 3506 published
recently.
A list of all parts in the ISO 3506 series can be found on the ISO website.
iv
ISO 3506-4:2025(en)
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.
v
ISO 3506-4:2025(en)
Introduction
The properties of stainless steel fasteners result from the chemical composition of the material (especially
corrosion resistance) and from the mechanical properties due to the manufacturing process. Austenitic,
ferritic and duplex (austenitic-ferritic) stainless steel fasteners are generally manufactured by cold working;
they consequently do not have homogeneous local material properties when compared to quenched and
tempered fasteners.
Austenitic-ferritic stainless steels referred to as duplex stainless steels were originally invented in the 1930s
and have been increasingly used since the 1980s. This document was revised to reflect their standardization
for fasteners.
All duplex stainless steels show improved resistance to stress corrosion cracking compared to the commonly
used A2 to A5 austenitic grades. Most duplex grades also show higher levels of pitting corrosion resistance,
where D2 matches at least A2 and where D4 matches at least A4.
vi
International Standard ISO 3506-4:2025(en)
Fasteners — Mechanical properties of corrosion-resistant
stainless steel fasteners —
Part 4:
Tapping screws with specified grades and hardness classes
1 Scope
This document specifies the mechanical and physical properties of tapping screws made of corrosion
resistant austenitic, martensitic, ferritic and duplex stainless steels, with specified grades and hardness
classes.
ISO 3506-6 provides general rules and additional technical information on suitable stainless steels and their
properties (detailed properties of stainless steel grades, corrosion behaviour with regards to pitting, crevice
and intergranular corrosion, magnetic properties, etc.).
WARNING — Tapping screws 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 –20 °C to +150 °C.
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 service environment conditions of the assembly (see also Clauses 5 and 6).
This document applies to tapping screws with threads ST2,2 to ST8, in accordance with ISO 1478.
This document does not apply to tapping screws with special properties, such as weldability.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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 1478, Tapping screws thread
ISO 1891-4, Fasteners — Vocabulary — Part 4: Control, inspection, delivery, acceptance and quality
ISO 3506-6, Fasteners — Mechanical properties of corrosion-resistant stainless steel fasteners — Part 6: General
rules for the selection of stainless steels and nickel alloys for fasteners
ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method
ISO 16228, Fasteners — Types of inspection documents
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
ISO 3506-4:2025(en)
3.1
tapping screw
sheet metal screw
screw with thread in accordance with ISO 1478 which, when driven into a hole, creates its own mating threads
in the materials of the parts being assembled (usually thin metal sheets) without deforming its own thread
3.2
stainless steel
steel with at least 10,5 % (mass fraction) of chromium (Cr) and maximum 1,2 % (mass fraction) of carbon (C)
[SOURCE: ISO 3506-1:2020, 3.5]
3.3
austenitic stainless steel
stainless steel (3.2) with high amounts of chromium and nickel which usually cannot be hardened by heat
treatment, providing excellent resistance to corrosion, good ductility, and usually low or non-magnetic
properties
[SOURCE: ISO 3506-1:2020, 3.6]
3.4
martensitic stainless steel
stainless steel (3.2) with high amounts of chromium but very little nickel or other alloying elements, which
can be hardened by heat treatment for increasing strength but with reduced ductility, and with highly
magnetic properties
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