Fasteners - Electroplated coating systems (ISO 4042:2018)

This document specifies requirements for electroplated coatings and coating systems on steel
fasteners. The requirements related to dimensional properties also apply to fasteners made of copper
or copper alloys.
It also specifies requirements and gives recommendations to minimize the risk of hydrogen
embrittlement; see 4.4 and Annex B.
It mainly applies to zinc and zinc alloy coating systems (zinc, zinc-nickel, zinc-iron) and cadmium,
primarily intended for corrosion protection and other functional properties:
— with or without conversion coating;
— with or without sealant;
— with or without top coat;
— with or without lubricant (integral lubricant and/or subsequently added lubricant).
Specifications for other electroplated coatings and coating systems (tin, tin-zinc, copper-tin, coppersilver,
copper, silver, copper-zinc, nickel, nickel-chromium, copper-nickel, copper-nickel-chromium)
are included in this document only for dimensional requirements related to fasteners with ISO metric
threads.
This document applies to bolts, screws, studs and nuts with ISO metric thread, to fasteners with non-
ISO metric thread, and to non-threaded fasteners such as washers, pins, clips and rivets.
Information for design and assembly of coated fasteners is given in Annex A.
This document does not specify requirements for properties such as weldability or paintability.
NOTE Other International Standards specify differing electroplating processes. For electroplating of
fasteners, the requirements of this document apply, unless otherwise agreed.

Verbindungselemente - Galvanisch aufgebrachte Überzugsysteme (ISO 4042:2018)

Dieses Dokument legt Anforderungen an galvanisch aufgebrachte Überzüge und Überzugsysteme auf Ver-bindungselementen aus Stahl fest. Die Maßanforderungen gelten auch für Verbindungselemente aus Kupfer oder Kupferlegierungen.
Es legt außerdem Anforderungen fest und gibt Empfehlungen, um das Risiko der Wasserstoffversprödung zu minimieren; siehe 4.4 und Anhang B.
Es gilt hauptsächlich für Zink- und Zinklegierungsüberzugsysteme (Zink, Zink-Nickel, Zink-Eisen) und Cadmium, die vor allem für den Korrosionsschutz und weitere funktionelle Eigenschaften bestimmt sind:
- mit oder ohne Konversionsschicht;
- mit oder ohne Versiegelung;
- mit oder ohne Deckschicht;
- mit oder ohne Schmiermittel (integriertes Schmiermittel und/oder nachträglich aufgebrachtes Schmier-mittel).
Die Festlegungen für weitere galvanisch aufgebrachte Überzüge und Überzugsysteme (Zinn, Zinn-Zink, Kupfer-Zinn, Kupfer-Silber, Kupfer, Silber, Kupfer-Zink, Nickel, Nickel-Chrom, Kupfer-Nickel, Kupfer-Nickel-Chrom) sind in diesem Dokument nur für Maßanforderungen in Bezug auf Verbindungselemente mit metri-schem ISO-Gewinde enthalten.
Dieses Dokument gilt für Schrauben und Muttern mit metrischem ISO-Gewinde, für Verbindungselemente mit nicht metrischem ISO-Gewinde und für Verbindungselemente ohne Gewinde, wie Scheiben, Stifte, Clips und Niete.
Hinweise zur konstruktiven Ausführung und zur Montage von beschichteten Verbindungselementen sind in Anhang A aufgeführt.
Dieses Dokument legt keine Anforderungen an Eigenschaften wie Schweißbarkeit oder Lackierbarkeit fest.
ANMERKUNG Andere Internationale Normen legen abweichende Galvanikprozesse fest. Für das Aufbringen galvanischer Überzüge auf Verbindungselemente gelten die Anforderungen dieses Dokumentes, sofern nicht anders vereinbart.

Fixations - Systèmes de revêtements électrolytiques (ISO 4042:2018)

Le présent document spécifie les exigences applicables aux revêtements et aux systèmes de revêtement électrolytiques destinés aux fixations en acier. Les exigences portant sur les caractéristiques dimensionnelles s'appliquent également aux fixations en cuivre ou en alliages de cuivre.
Il spécifie également les exigences et donne des recommandations visant à réduire le risque de fragilisation par l'hydrogène; voir 4.4 et Annexe B.
Il s'applique principalement aux systèmes de revêtement de zinc et d'alliage de zinc (zinc, zinc-nickel, zinc-fer) et de cadmium, essentiellement destinés à la protection contre la corrosion et à l'obtention d'autres caractéristiques fonctionnelles:
—          avec ou sans couche de conversion;
—          avec ou sans finitions «sealer»;
—          avec ou sans finition «top coat»;
—          avec ou sans lubrifiant (lubrifiant intégré et/ou lubrifiant additionnel).
Les spécifications concernant d'autres revêtements et systèmes de revêtement électrolytiques (étain, étain-zinc, cuivre-étain, cuivre-argent, cuivre, argent, cuivre-zinc, nickel, nickel-chrome, cuivre-nickel, cuivre-nickel-chrome) sont incluses dans le présent document uniquement pour les exigences dimensionnelles relatives aux fixations à filetage métrique ISO.
Le présent document s'applique aux vis, goujons, tiges filetées et écrous à filetage métrique ISO, aux fixations à filetage non métrique ISO et aux fixations non filetées telles que les rondelles, les goupilles, les clips et les rivets.
Des informations sur la conception et l'assemblage des fixations revêtues sont données à l'Annexe A.
Le présent document ne spécifie pas d'exigence pour les caractéristiques telles que la soudabilité ou l'aptitude à la peinture.
NOTE       Des procédés de revêtement électrolytique différents sont spécifiés dans d'autres Normes internationales. Pour le revêtement électrolytique des fixations, les exigences du présent document s'appliquent, sauf accord contraire.

Mehanski vezni elementi - Sistemi galvanskih prevlek veznih elementov (ISO 4042:2018)

Ta dokument določa zahteve za galvanske prevleke veznih elementov in sisteme prevlek na mehanskih veznih elementih. Zahteve, povezane z dimenzijskimi lastnostmi, veljajo tudi za vezne elemente, izdelane iz bakra in bakrovih zlitin.
Določa tudi zahteve in podaja priporočila za zmanjševanje tveganja za krhkost v stiku z vodikom (glej 4.4. in dodatek B).
Uporablja se predvsem za sisteme cinkovih prevlek ter prevlek iz cinkovih zlitin (cink, cink-nikelj, cink-železo) in kadmija, namenjene predvsem za zaščito proti koroziji in zagotavljanje drugih funkcionalnih lastnosti:
– s konverzijskim premazom ali brez njega;
– s tesnilom ali brez njega;
– z vrhnjim premazom ali brez njega;
– z mazivom (integriranim ali naknadno dodanim) ali brez njega.
Specifikacije za druge galvanske prevleke in sisteme prevlek (kositer, kositer-cink, baker-kositer, baker-srebro, baker, srebro, baker-cink, nikelj, nikelj-krom, baker-nikelj, baker-nikelj-krom) so zajete v tem dokumentu samo za dimenzijske zahteve, povezane z veznimi elementi z ISO-metričnimi navoji.
Ta dokument se uporablja za vijake in matice z ISO-metričnim navojem, vezne elemente z metričnimi navoji, ki niso del ISO, ter vezne elemente brez navojev, kot so podložke, zatiči, objemke in zakovice.
Informacije o projektiranju in sestavljanju prevlečenih veznih elementov so podane v dodatku A. Ta dokument ne določa zahtev za lastnosti veznih elementov, kot je varivost ali možnost barvanja.
OPOMBA: Različne postopke galvanizacije določajo drugi mednarodni standardi. Če ni dogovorjeno drugače, za galvanizirane vezne elemente veljajo zahteve tega dokumenta.

General Information

Status
Withdrawn
Public Enquiry End Date
31-Jul-2017
Publication Date
02-Oct-2018
Withdrawal Date
22-Jun-2022
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
22-Jun-2022
Due Date
15-Jul-2022
Completion Date
23-Jun-2022

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SLOVENSKI STANDARD
SIST EN ISO 4042:2018
01-december-2018
1DGRPHãþD
SIST EN ISO 4042:2001
Mehanski vezni elementi - Sistemi galvanskih prevlek veznih elementov (ISO
4042:2018)
Fasteners - Electroplated coating systems (ISO 4042:2018)
Verbindungselemente - Galvanisch aufgebrachte Überzugsysteme (ISO 4042:2018)
Fixations - Systèmes de revêtements électrolytiques (ISO 4042:2018)
Ta slovenski standard je istoveten z: EN ISO 4042:2018
ICS:
21.060.01 Vezni elementi na splošno Fasteners in general
25.220.40 Kovinske prevleke Metallic coatings
SIST EN ISO 4042:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 4042:2018
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SIST EN ISO 4042:2018
EN ISO 4042
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2018
EUROPÄISCHE NORM
ICS 21.060.01 Supersedes EN ISO 4042:1999
English Version
Fasteners - Electroplated coating systems (ISO 4042:2018)

Fixations - Systèmes de revêtements électrolytiques Verbindungselemente - Galvanisch aufgebrachte

(ISO 4042:2018) Überzugsysteme (ISO 4042:2018)
This European Standard was approved by CEN on 4 July 2018.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey 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

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4042:2018 E

worldwide for CEN national Members.
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SIST EN ISO 4042:2018
EN ISO 4042:2018 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 4042:2018
EN ISO 4042:2018 (E)
European foreword

This document (EN ISO 4042:2018) 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 March 2019, and conflicting national standards shall

be withdrawn at the latest by March 2019.

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 4042:1999.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 4042:2018 has been approved by CEN as EN ISO 4042:2018 without any modification.

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SIST EN ISO 4042:2018
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SIST EN ISO 4042:2018
INTERNATIONAL ISO
STANDARD 4042
Third edition
2018-08
Fasteners — Electroplated coating
systems
Fixations — Systèmes de revêtements électrolytiques
Reference number
ISO 4042:2018(E)
ISO 2018
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SIST EN ISO 4042:2018
ISO 4042:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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SIST EN ISO 4042:2018
ISO 4042:2018(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ..............................................................................................................................................................................................................................vii

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 General characteristics of the coating ............................................................................................................................................ 3

4.1 Coating metals or alloys and main purposes ................................................................................................................ 3

4.2 Build-up of basic electroplated coating systems ....................................................................................................... 3

4.3 Coating systems and coating processes............................................................................................................................. 4

4.4 Internal hydrogen embrittlement........................................................................................................................................... 4

4.4.1 General...................................................................................................................................................................................... 4

4.4.2 Fasteners with hardness below 360 HV ...................................................................................................... 5

4.4.3 Fasteners with hardness equal to and above 360 HV and up to 390 HV ......................... 5

4.4.4 Fasteners with hardness above 390 HV ....................................................................................................... 5

4.4.5 Fasteners in accordance with ISO 898-1, ISO 898-2 and ISO 898-3 ................................... 6

4.4.6 Baking and test requirements for case-hardened and tempered screws ....................... 7

4.4.7 Work-hardened fasteners ......................................................................................................................................... 8

4.4.8 Fasteners with bainitic structure ...................................................................................................................... 8

4.5 Baking ............................................................................................................................................................................................................. 8

5 Corrosion protection and testing ........................................................................................................................................................ 8

5.1 General ........................................................................................................................................................................................................... 8

5.2 Neutral salt spray test (NSS) for zinc based coating systems ......................................................................... 9

5.3 Sulfur dioxide test (Kesternich test) .................................................................................................................................10

5.4 Bulk handling, automatic processes such as feeding and/or sorting, storage and

transport .................. ..................................................................................................................................................................................11

6 Dimensional requirements and testing .....................................................................................................................................11

6.1 General ........................................................................................................................................................................................................11

6.2 Fasteners with ISO metric thread ........................................................................................................................................11

6.2.1 Coating thickness .........................................................................................................................................................11

6.2.2 Gaugeability and assemblability .....................................................................................................................12

6.3 Other fasteners ....................................................................................................................................................................................12

6.4 Test methods for thickness determination ..................................................................................................................13

7 Mechanical and physical properties and testing ..............................................................................................................15

7.1 General ........................................................................................................................................................................................................15

7.2 Appearance .............................................................................................................................................................................................15

7.3 Corrosion resistance related to temperature ............................................................................................................15

7.4 Torque/clamp force relationship .........................................................................................................................................15

7.5 Determination of hexavalent chromium ........................................................................................................................15

8 Applicability of tests ......................................................................................................................................................................................15

8.1 General ........................................................................................................................................................................................................15

8.2 Tests mandatory for each lot ...................................................................................................................................................15

8.3 Tests for in-process control.......................................................................................................................................................16

8.4 Tests to be performed when specified by the purchaser .................................................................................16

9 Designation system .........................................................................................................................................................................................16

9.1 General ........................................................................................................................................................................................................16

9.2 Designation of electroplated coating systems for the order .........................................................................17

9.3 Examples of designation of hexavalent chromium free electroplated coating

systems for fasteners ......................................................................................................................................................................18

9.4 Designation of fasteners with electroplated coating systems for labelling .....................................19

10 Ordering requirements for electroplating .............................................................................................................................19

© ISO 2018 – All rights reserved iii
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SIST EN ISO 4042:2018
ISO 4042:2018(E)

11 Storage conditions ...........................................................................................................................................................................................20

Annex A (informative) Design aspects and assembly of coated fasteners ..................................................................21

Annex B (informative) Hydrogen embrittlement consideration ..........................................................................................29

Annex C (informative) Corrosion protection related to zinc coatings with chromate

conversion coatings ........................................................................................................................................................................................33

Annex D (informative) Coating thickness and thread clearance for ISO metric screw threads ...........34

Annex E (informative) Coating systems tested in accordance with ISO 9227, NSS —

Evaluation of cabinet corrosivity for the neutral salt spray test .....................................................................42

Annex F (informative) Obsolete designation codes for electroplated coating systems on

fasteners according to ISO 4042:1999 ........................................................................................................................................51

Bibliography .............................................................................................................................................................................................................................54

iv © ISO 2018 – All rights reserved
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SIST EN ISO 4042:2018
ISO 4042:2018(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 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.

This document was prepared by Technical Committee ISO/TC 2, Fasteners, Subcommittee SC 14, Surface

coatings.

This third edition cancels and replaces the second edition (ISO 4042:1999), which has been technically

revised. The main changes compared to the previous edition are as follows:

— application to all fasteners, including self-tapping and thread forming screws, washers, rivets,

clips, etc.;
— focus on coatings designed for corrosion protection of fasteners;

— application to electroplated coating systems with or without additional layers (conversion coating,

sealant, top coat, lubricant);
— specification of minimum corrosion resistance (white corrosion and red rust);

— inclusion of up-to-date knowledge about hydrogen embrittlement and prevention measures;

— definitions specified in ISO 1891-2;

— concerning corrosion tests, inclusion of sulfur dioxide test (Kesternich) and calibration of neutral

salt spray test;
— inclusion of gaugeability and assemblability requirements;

— for thickness determination, addition of adequate test methods and deletion of the batch average

thickness;
— new designation system for all coating systems;
— specification for mechanical and physical properties and related test methods;
— information about design aspects and assembly of coated fasteners;
© ISO 2018 – All rights reserved v
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SIST EN ISO 4042:2018
ISO 4042:2018(E)

— information for coating thickness and thread clearance for ISO metric screw threads;

— information about evaluation of cabinet corrosivity for the neutral salt spray test.

vi © ISO 2018 – All rights reserved
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SIST EN ISO 4042:2018
ISO 4042:2018(E)
Introduction

This document was completely revised to take into account new developments related to hexavalent

chromium free passivations, application of sealants and top coats, requirements for functional

properties as well as results of research work to minimize the risk of hydrogen embrittlement.

© ISO 2018 – All rights reserved vii
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SIST EN ISO 4042:2018
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SIST EN ISO 4042:2018
INTERNATIONAL STANDARD ISO 4042:2018(E)
Fasteners — Electroplated coating systems
1 Scope

This document specifies requirements for electroplated coatings and coating systems on steel

fasteners. The requirements related to dimensional properties also apply to fasteners made of copper

or copper alloys.

It also specifies requirements and gives recommendations to minimize the risk of hydrogen

embrittlement; see 4.4 and Annex B.

It mainly applies to zinc and zinc alloy coating systems (zinc, zinc-nickel, zinc-iron) and cadmium,

primarily intended for corrosion protection and other functional properties:
— with or without conversion coating;
— with or without sealant;
— with or without top coat;

— with or without lubricant (integral lubricant and/or subsequently added lubricant).

Specifications for other electroplated coatings and coating systems (tin, tin-zinc, copper-tin, copper-

silver, copper, silver, copper-zinc, nickel, nickel-chromium, copper-nickel, copper-nickel-chromium)

are included in this document only for dimensional requirements related to fasteners with ISO metric

threads.

This document applies to bolts, screws, studs and nuts with ISO metric thread, to fasteners with non-

ISO metric thread, and to non-threaded fasteners such as washers, pins, clips and rivets.

Information for design and assembly of coated fasteners is given in Annex A.

This document does not specify requirements for properties such as weldability or paintability.

NOTE Other International Standards specify differing electroplating processes. For electroplating of

fasteners, the requirements of this document apply, unless otherwise agreed.
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 1456, Metallic and other inorganic coatings — Electrodeposited coatings of nickel, nickel plus

chromium, copper plus nickel and of copper plus nickel plus chromium

ISO 1463, Metallic and oxide coatings — Measurement of coating thickness — Microscopical method

ISO 1502, ISO general-purpose metric screw threads — Gauges and gauging

ISO 1891-2, Fasteners — Terminology — Part 2: Vocabulary and definitions for coatings

ISO 2081, Metallic and other inorganic coatings — Electroplated coatings of zinc with supplementary

treatments on iron or steel

ISO 2082, Metallic and other inorganic coatings — Electroplated coatings of cadmium with supplementary

treatments on iron or steel
© ISO 2018 – All rights reserved 1
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SIST EN ISO 4042:2018
ISO 4042:2018(E)
ISO 2093, Electroplated coatings of tin — Specification and test methods

ISO 2177, Metallic coatings — Measurement of coating thickness — Coulometric method by anodic

dissolution

ISO 2178, Non-magnetic coatings on magnetic substrates — Measurement of coating thickness —

Magnetic method

ISO 3231, Paints and varnishes — Determination of resistance to humid atmospheres containing sulfur dioxide

ISO 3497, Metallic coatings — Measurement of coating thickness — X-ray spectrometric methods

ISO 3613:2010, Metallic and other inorganic coatings — Chromate conversion coatings on zinc, cadmium,

aluminium-zinc alloys and zinc-aluminium alloys — Test methods

ISO 4521, Metallic and other inorganic coatings — Electrodeposited silver and silver alloy coatings for

engineering purposes — Specification and test methods

ISO 6988, Metallic and other non organic coatings — Sulfur dioxide test with general condensation of

moisture
ISO 8991, Designation system for fasteners
ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests

ISO 15330, Fasteners — Preloading test for the detection of hydrogen embrittlement — Parallel bearing

surface method

ISO 15726, Metallic and other inorganic coatings — Electrodeposited zinc alloys with nickel, cobalt or iron

ISO 16047, Fasteners — Torque/clamp force testing
ISO 16228, Fasteners — Types of inspection documents

ISO 19598, Metallic coatings — Electroplated coatings of zinc and zinc alloys on iron or steel with

supplementary Cr(VI)-free treatment

ISO 21968, Non-magnetic metallic coatings on metallic and non-metallic basis materials — Measurement

of coating thickness — Phase-sensitive eddy-current method

ASME B18.6.3, Machine Screws, Tapping Screws, and Metallic Drive Screws (Inch Series)

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 1891-2 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
reference panel

reference material that is to be exposed to check the corrosivity level of the test cabinet used for

fastener testing
2 © ISO 2018 – All rights reserved
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SIST EN ISO 4042:2018
ISO 4042:2018(E)
4 General characteristics of the coating
4.1 Coating metals or alloys and main purposes

Electroplated coating systems for steel fasteners are primarily applied for corrosion protection and

functional properties, such as torque/clamp force relationship.

In addition, other functional properties or decorative properties can be specified; see Annex A.

Table 1 shows commonly used electroplated coatings in relation with their main purposes and

references to related ISO standards, which give additional general information not covered by this

document, e.g. for designation. Some of the International Standards listed in Table 1 specify differing

electroplating processes. For the purpose of fasteners, the requirements of this document apply.

Table 1 — Electroplated coatings in accordance with their main purposes and related

ISO standards
Main purpose of
Coating metal(s) Nature the coating for ISO standard
fasteners
Symbol Element
Zn Zinc Metal P/D/F ISO 2081, ISO 19598
ZnNi Zinc-nickel Alloy P/D/F ISO 15726, ISO 19598
ZnFe Zinc-iron Alloy P/D/F ISO 15726, ISO 19598
Cd Cadmium Metal P/F ISO 2082
Ni Nickel Metal D/F ISO 1456
Ni+Cr Nickel-chromium Multi-layer D ISO 1456
Cu+Ni Copper-nickel Multi-layer D ISO 1456
Cu+Ni+Cr Copper-nickel-chromium Multi-layer D ISO 1456
CuZn Brass Alloy D —
CuSn Copper-tin (bronze) Alloy F —
Cu Copper Metal F/D —
Ag Silver Metal F/D ISO 4521
CuAg Copper-silver Alloy F —
Sn Tin Metal F ISO 2093
SnZn Tin-zinc Metal F/P —
P corrosion protection
F functional properties
D decorative properties (colour, aspect)

Cadmium is restricted or prohibited for many applications (remaining cadmium users are predominantly military and

aerospace industries).
4.2 Build-up of basic electroplated coating systems
Figure 1 shows basic electroplated coating systems.
© ISO 2018 – All rights reserved 3
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SIST EN ISO 4042:2018
ISO 4042:2018(E)
Key
1 only metal layer(s)
2 metal layer(s) + conversion coating
3 metal layer(s) + conversion coating + additional lubricant
4 metal layer(s) + conversion coating + sealant/top coat
5 metal layer(s) + conversion coating + sealant/top coat + additional lubricant
Figure 1 — Basic electroplated coating systems (schematic)

A conversion coating increases corrosion protection on zinc, zinc alloys and cadmium coatings. It may

be a passivation (chromium VI free) or a chromatation (chromium VI containing). The conversion

coating can also provide better adhesion for additional layer(s) and/or additional colour/paint.

An additional sealant/top coat (with or without integral lubricant) may be chosen to increase corrosion

resistance and to achieve other specific properties (e.g. torque/clamp force properties, resistance to

chemicals, mechanical resistance, aspect, colour, thermal stability, increased electrical resistance, UV

radiation resistance). The selection of the nature of a sealant or top coat should be based on desired

additional properties.

An additional lubricant may be applied to adjust or amend the torque/clamp force relationship.

4.3 Coating systems and coating processes

The type and geometry of the fasteners should be considered when selecting a coating system and the

related coating process (see Annex A) as well as hydrogen embrittlement considerations (see Annex B).

The electroplating process shall be under control, in accordance with a recognized standard and/or a

specification by agreement with the customer.
4.4 Internal hydrogen embrittlement
4.4.1 General
If the three following conditions are concurrently present for fasteners:

— with high tensile strength or hardness or which have been case-hardened and tempered or cold

worked to high hardness,
— which are under tensile stress, and
— which have absorbed hydrogen,
there is a risk of Internal Hydrogen Embrittlement (IHE).

The susceptibility to IHE increases with increasing hardness of the fastener material. Appropriate

measures for prevention of IHE for quenched and tempered fasteners depending on hardness are

4 © ISO 2018 – All rights reserved
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SIST EN ISO 4042:2018
ISO 4042:2018(E)
specified in Table 2. For fasteners in accorda
...

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