EN 2516:2023

SLOVENSKI STANDARD
01-februar-2024
Aeronavtika - Pasiviranje korozijsko odpornih jekel in dekontaminacija nikljevih ali
kolbatovih zlitin
Aerospace series - Passivation of corrosion resisting steels and decontamination of
nickel or cobalt base alloys
Luft- und Raumfahrt - Passivieren von korrosionsbeständigen Stählen und
Dekontaminierung von Nickel- oder Kobaltlegierungen
Série aérospatiale - Passivation des aciers résistant à la corrosion et décontamination
des alliages base nickel ou cobalt
Ta slovenski standard je istoveten z: EN 2516:2023
ICS:
49.025.10 Jekla Steels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 2516
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2023
EUROPÄISCHE NORM
ICS 49.040 Supersedes EN 2516:2020
English Version
Aerospace series - Passivation of corrosion resisting steels
and decontamination of nickel or cobalt base alloys
Série aérospatiale - Passivation des aciers résistant à la Luft- und Raumfahrt - Passivieren von
corrosion et décontamination des alliages base nickel korrosionsbeständigen Stählen und Dekontaminierung
ou cobalt von Nickel- oder Kobaltlegierungen
This European Standard was approved by CEN on 9 July 2023.

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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 2516:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Purpose of process . 4
5 Applicability and limitations of the process . 4
6 Information for the processor . 5
7 Condition of the parts prior to processing. 5
8 Pre-treatments . 5
9 Treatment . 6
9.1 Process approval . 6
9.2 De-embrittlement in case of acid pickling . 7
10 Required characteristics and inspections . 7
10.1 Parts . 7
10.1.1 Visual testing . 7
10.1.2 Absence of iron contamination . 8
10.2 Process . 8
10.2.1 General. 8
10.2.2 Water quality . 8
10.2.3 Passivation and/or decontamination bath . 8
11 Quality assurance . 8
11.1 Approval of the processor. 8
11.2 Process qualification . 9
11.3 Acceptance. 9
11.4 Fault sanction . 9
12 Health, safety and environmental aspects . 9
13 Designation . 9
Annex A (informative) Recommended passivation solutions . 10
Annex B (informative) Standard evolution form . 13
Bibliography . 15

European foreword
This document (EN 2516:2023) has been prepared by the Aerospace and Defence Industries
Association of Europe — Standardization (ASD-STAN).
After enquiries and votes carried out in accordance with the rules of this Association, this
document has received the approval of the National Associations and the Official Services of the
member countries of ASD-STAN, prior to its presentation to CEN.
This document shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by June 2024, and conflicting national standards shall be
withdrawn at the latest by June 2024.
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 2516:2020.
The main changes with respect to the previous edition are listed in Annex B.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this document: 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.
1 Scope
This document specifies several chemical methods of passivation for corrosion resisting steels
(austenitic, ferritic, martensitic and precipitation hardenable) and of decontamination for nickel or
cobalt base alloys.
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.
EN ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests (ISO 9227)
3 Terms and definitions
No terms and definitions are listed in this document.
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/
4 Purpose of process
To improve the corrosion resistance characteristics of a part after such treatments as machining,
forming, tumbling and shot peening by removing foreign metal contamination due to these operations.
Passivation shall not be used on castings, welded or brazed parts, carburized or nitrided surfaces nor on
parts with mating surfaces when entrapment of acids may occur.
5 Applicability and limitations of the process
This document is applicable for the corrosion resisting alloys listed in Table A.2.
This document is not applicable for:
— unalloyed or low-alloyed carbon steel;
— powder metallurgy alloys;
— surface modified steel i.e. with case-hardened, carburized or nitrided surfaces;
— soldered or brazed parts;
— items containing joints and cavities where it is not possible to mask prior to passivation or to
ensure complete removal of the passivation solution.

6 Information for the processor
— Designation, refer to Clause 13.
— Reference of the material standard and its metallurgical condition.
— Process schedule, if necessary.
— Areas to be masked.
7 Condition of the parts prior to processing
Fabrication of the parts shall have been completed before treatment.
8 Pre-treatments
All parts shall be submitted to a surface preparation process. The surface preparation process may
include mechanical and/or chemical and/or electrochemical methods, singly or in combination.
Necessary sub steps (e.g. cleaning, degreasing, descaling, abrasive blasting, activation, pickling, rinsing,
drying, masking) depend on the degree of contamination. Although descaling or other steps may be
necessary before passivation can be effective, these steps shall be indicated in the process instructions.
The composition of appropriate surface preparation chemicals may depend on the grade of the
corrosion resisting steel to be treated. Alloying elements, contaminations and mechanical processing
may influence the sensitivity of the corrosion resisting steels and nickel or cobalt base alloys.
The result of the surface preparation treatment shall demonstrate a reproducible process and surface
condition. Particularly, the resulting conditioned parts shall be substantially free of contaminants and
other undesired organic and metallic residues from storage, transport and fabrication processes (e.g.
oil, grease, forming compounds, lubricants, coolants, cutting fluids, rust, scale, foreign metal or other
contaminations).
The surface preparation shall not induce pitting corrosion or intergranular corrosion. It shall only be
used on corrosion resisting alloys not susceptible to pitting or sensitive to intergranular corrosion by
the pickling solution which is most frequently an aqueous solution of nitric and hydrofluoric acids. The
concentration can be adjusted within very wide limits by varying the proportions of the ingredients and
by adjusting operating temperatures.
Remaining contamination or damage shall lead to rejection or rework of the components.
9 Treatment
9.1 Process approval
The chemical composition of the bath shall be chosen according to Table 1.
Table 1 — Bath type
Chemical composition
Sodium
Type Temperature Time
dichromate Citric acid
Nitric acid HNO
Na Cr O , C H O
2 2 7 6 8 7
2H O
c
ml/l g/l g/l °C min
from 50 to 55 from 20 to 40
a
C1 from 200 to 250 from 20 to 30 —
from 20 to 30 from 30 to 60
C2 from 200 to 500 — from 20 to 30 from 30 to 60
d
A) from 200 to 250 from 20 to 30 from 50 to 55 from 2 to 3
b
C3
B) — from 40 to 60 — from 60 to 70 from 30 to 40
A) from 200 to 250 from 20 to 30 from 50 to 55 from 20 to 40
b
C4
B) — from 40 to 60 from 60 to 70 from 30 to 40
C5 from 200 to 250 from 20 to 30 from 30 to 60
C6 from 250 to 450 from 20 to 30 ≥ 30
C7 from 200 to 250 — — from 50 to 60 ≥ 20
C8 from 450 to 550 from 50 to 55 ≥ 30
C9 from 450 to 550 from 20 to 30 from 20 to 35
C10 from 60 to 70 ≥ 4
C11 — — from 40 to 100 from 50 to 60 ≥ 10
C12 from 20 to 50 ≥ 20
from 120 ml/l to
180 ml/l + CuSO
c
C13 5H O (copper — — from 55 to 65 ≥ 20
sulfate) from 40 g/l
to 100 g/l
NOTE Nitric acid concentration shown is by volume of 42° Baume (density: 1,4, nitric acid).
a
One of the two options shall be applied.
b
Use A) then B) after intermediate rinsing with clean water.
c
With additional wetting agents and inhibito
...