EN 4704:2012
(Main)Aerospace series - Tartaric-Sulphuric-Acid anodizing of aluminium and aluminium wrought alloys for corrosion protection and paint pre-treatment (TSA)
Aerospace series - Tartaric-Sulphuric-Acid anodizing of aluminium and aluminium wrought alloys for corrosion protection and paint pre-treatment (TSA)
This European Standard defines the requirement for Tartaric-Sulphuric-Acid (TSA) anodizing of aluminium and wrought alloys for corrosion protection and paint pre-treatment.
The purpose of this European Standard is to give design and quality requirements to manufactures.
Luft- und Raumfahrt - Weinsäure-Schwefelsäure-Anodisieren (TSA) von Aluminium und Aluminium-Knetlegierungen für den Korrosionsschutz und zur Vorbehandlung
Série aérospatiale - Anodisation tartrique de l'aluminium et des alliages d'aluminium corroyés pour protection contre la corrosion et peinture (TSA)
La présente Norme européenne définit les exigences de l’anodisation tartrique sulfurique de l’aluminium et des alliages corroyés pour la protection contre la corrosion et le prétraitement de la peinture.
Le but de la présente Norme européenne est de fournir les exigences de conception et de qualité aux fabricants.
Aeronavtika - Eloksiranje aluminija in gnetljivih (kovnih) aluminijskih zlitin z vinsko-žvepleno kislino (TSA) za korozijsko zaščito in barvno predobdelavo
Ta evropski standard določa zahtevo za eloksiranje aluminija in gnetljivih (kovnih) aluminijevih zlitin z vinsko-žvepleno kislino (TSA) za korozijsko zaščito in barvno predobdelavo. Namen tega evropskega standarda je določiti zahteve za proizvajalce glede zasnove in kakovosti.
General Information
Overview
EN 4704:2012 (CEN) is an aerospace series standard that specifies requirements for Tartaric–Sulphuric‑Acid (TSA) anodizing of aluminium and wrought aluminium alloys used for corrosion protection and paint pre-treatment. It defines process, inspection, quality and qualification requirements to ensure reproducible anodic films suitable for aerospace components.
Key topics and technical requirements
- Process scope: TSA anodizing as an electrochemical process using tartaric and sulphuric acids, including required surface preparation (alkaline cleaning/etching, acidic pickling/desmutting), rinsing and optional sealing.
- Limitations: TSA shall not be used for metal bonding, inside oxygen pipes, for long narrow tubes/holes (length/diameter ratios >10:1 or trapped holes >5:1), or on assemblies that permanently entrap fluids unless masked.
- Film properties:
- Thickness: specified range 2 µm to 7 µm (measured by eddy current, optical microscopy, SEM or equivalent).
- Film weight: > 22 mg/dm2 (EN ISO 2106 gravimetric method).
- Visual quality: free from powdery areas, blisters, burnings, scratches and smut.
- Corrosion and paint performance:
- Salt spray (EN ISO 9227) criteria for unpainted sealed specimens: <2 pits/dm2, no pit >0.8 mm, no patchy dark grey areas after minimum 14 days for specified alloys.
- Paint adhesion per EN ISO 2409: Class 0 initially; Class 1 after 14 days water immersion.
- Filiform corrosion (EN 3665): maximum filament length ≤ 2 mm at 40 days.
- Process control & quality:
- Water quality requirements for baths and final rinses (demineralized water; pH 5.0–7.0; total residue ≤20 mg/l; conductivity ≤20 µS/cm).
- Defined frequency of serial checks (visual, thickness, film weight, corrosion resistance, sealing quality, paint adhesion).
- Re‑anodizing: one re-anodizing allowed; further rework requires agreement.
- Qualification Test Report (QTR): documents shop, process instructions, parameters (bath composition, temperatures, times, voltages), tests and full results.
Applications / Who uses this standard
- Aerospace OEMs, tier‑1 suppliers and coating shops specifying or performing TSA anodizing for aircraft structural parts.
- Process engineers, quality/inspection teams and procurement/spec writers who need to verify corrosion protection and paint pretreatment compliance.
- Test labs conducting salt spray, adhesion, filiform and fatigue tests to qualify TSA processes for aerospace alloys.
Related standards
- EN 2101 (chromic anodizing)
- EN 3665 (filiform corrosion test)
- EN 6072 (fatigue testing)
- EN ISO 2106, EN ISO 2409, EN ISO 9227, EN ISO 15528
Keywords: EN 4704:2012, TSA anodizing, Tartaric‑Sulphuric‑Acid anodizing, aluminium anodizing, corrosion protection, paint pre‑treatment, aerospace standard.
Frequently Asked Questions
EN 4704:2012 is a standard published by the European Committee for Standardization (CEN). Its full title is "Aerospace series - Tartaric-Sulphuric-Acid anodizing of aluminium and aluminium wrought alloys for corrosion protection and paint pre-treatment (TSA)". This standard covers: This European Standard defines the requirement for Tartaric-Sulphuric-Acid (TSA) anodizing of aluminium and wrought alloys for corrosion protection and paint pre-treatment. The purpose of this European Standard is to give design and quality requirements to manufactures.
This European Standard defines the requirement for Tartaric-Sulphuric-Acid (TSA) anodizing of aluminium and wrought alloys for corrosion protection and paint pre-treatment. The purpose of this European Standard is to give design and quality requirements to manufactures.
EN 4704:2012 is classified under the following ICS (International Classification for Standards) categories: 49.040 - Coatings and related processes used in aerospace industry. The ICS classification helps identify the subject area and facilitates finding related standards.
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Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2012
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Aerospace series - Tartaric-Sulphuric-Acid anodizing of aluminium and aluminium
wrought alloys for corrosion protection and paint pre-treatment (TSA)
Luft- und Raumfahrt - Weinsäure-Schwefelsäure-Anodisieren (TSA) von Aluminium und
Aluminium-Knetlegierungen für den Korrosionsschutz und zur Vorbehandlung
Série aérospatiale - Anodisation tartrique de l'aluminium et des alliages d'aluminium
corroyés pour protection contre la corrosion et peinture (TSA)
Ta slovenski standard je istoveten z: EN 4704:2012
ICS:
49.025.20 Aluminij Aluminium
49.040 Prevleke in z njimi povezani Coatings and related
postopki, ki se uporabljajo v processes used in aerospace
letalski in vesoljski industriji industry
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN 4704
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2012
ICS 49.040
English Version
Aerospace series - Tartaric-Sulphuric-Acid anodizing of
aluminium and aluminium wrought alloys for corrosion protection
and paint pre-treatment (TSA)
Série aérospatiale - Anodisation tartrique de l'aluminium et Luft- und Raumfahrt - Weinsäure-Schwefelsäure-
des alliages d'aluminium corroyés pour protection contre la Anodisieren (TSA) von Aluminium und Aluminium-
corrosion et peinture (TSA) Knetlegierungen für den Korrosionsschutz und zur
Vorbehandlung
This European Standard was approved by CEN on 23 December 2011.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 4704:2012: E
worldwide for CEN national Members.
Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms and definitions .4
4 Principle .5
5 Requirements .6
6 Re-anodizing . 10
7 Qualification Test Report (QTR) . 11
Annex A (informative) Wöhler curves and stress levels – Reference fatigue curves . 12
Bibliography . 13
Foreword
This document (EN 4704:2012) 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 Standard has
received the approval of the National Associations and the Official Services of the member countries of ASD,
prior to its presentation to CEN.
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 August 2012, and conflicting national standards shall be withdrawn at
the latest by August 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland, Turkey and the United Kingdom.
1 Scope
This European Standard defines the requirement for Tartaric-Sulphuric-Acid (TSA) anodizing of aluminium
and wrought alloys for corrosion protection and paint pre-treatment.
The purpose of this European Standard is to give design and quality requirements to manufactures.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 2101, Aerospace series — Chromic acid anodizing of aluminium and wrought aluminium alloys
EN 3665, Aerospace series — Test methods for paints and varnishes — Filiform corrosion resistance test on
aluminium alloys
EN 6072, Aerospace series — Metallic materials — Test methods — Constant amplitude fatique testing
EN ISO 2106, Anodizing of aluminium and its alloys — Determination of mass per unit area (surface density)
of anodic oxidation coatings — Gravimetric method (ISO 2106:2011)
EN ISO 2409, Paints and varnishes — Cross-cut test (ISO 2409)
EN ISO 9227 Corrosion tests in artificial atmospheres — Salt spray tests (ISO 9227)
EN ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling (ISO 15528)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
de-anodizing
process, which removes the anodic oxide
3.2
smut
precipitations of alloying elements (e. g. Cu, Fe, Zn, Si) on the surface of parts after a process step normally
after alkaline etching step
3.3
Mechanically Disturbed Layer
MDL
layer that is present at the surface resulting from the rolling process of the material
3.4
pit
surface corrosion defect at which the anodic coating is penetrated
3.5
process instruction
document that describes the detailed process, parameters, detailed steps, etc.
3.6
alloys
all aluminium alloys, that are treated with the TSA process in the specific shop
3.7
re-anodizing
repetition of the anodizing process step after complete de-anodizing
3.8
sealing
sealing (of the anodized layers) is applied to close the pores produced by the acid anodizing process. It is
usually applied in demineralized water bath. Sealing can improve the corrosion resistance performance of the
anodic film.
3.9
dichromate sealing
the dichromate sealing process has to be applied for unpainted parts
It content one of the following products:
Sodium dichromate;
Potassium dichromate.
It includes chromate and has to be replaced by a chromium III chemical conversion coating when available.
4 Principle
4.1 General description of process
TSA process is an electrochemical process used for generating an aluminium oxide layer for corrosion
protection and surface treatment prior to application of a corrosion-inhibiting primer.
The TSA process is characterized by using an electrolyte composed of tartaric and sulphuric acid. Suitable
surface preparation steps, e. g. alkaline cleaning, alkaline etching, acidic pickling/desmutting and subsequent
steps such as rinsing (and sealing, if applicable), have to be defined and are integral to the TSA process.
4.2 Limitations
All processes that can compromise the anodic film such as forming, or heat-treatment shall be performed prior
to surface preparation of the parts to be anodized.
TSA anodizing shall not be applied:
for metal bonding applications;
inside of oxygen pipes;
for tubes, pipes and open holes with a length to diameter ratio higher than 10:1;
for trapped holes with a length to a diameter ratio greater than 5:1;
for parts or assemblies (e.g. spot-welded and riveted), which can permanently entrap;
for components which can permanently entrap treatment solutions, except components that can be
adequately masked.
NOTE The formation of oxide layer influ
...
Die Norm EN 4704:2012 behandelt die Tartaric-Sulphuric-Acid (TSA) Anodisierung von Aluminium und Aluminium-Werkstoffen zur Korrosionsschutz und Behandlung vor dem Lackieren. Diese europäische Norm legt verbindliche Anforderungen fest, die sich an Hersteller richten und somit einen klaren Rahmen für die Produktion und die Qualitätssicherung schaffen. Die Relevanz dieser Norm ist insbesondere in der Luft- und Raumfahrtindustrie zu erkennen, in der eine hohe Materialstandards und Korrosionsbeständigkeit unabdingbar sind. Ein hervorstechender Punkt der EN 4704:2012 ist ihre umfassende Beschreibung der Verfahrensschritte und der erforderlichen Materialien für die TSA-Anodisierung. Hierbei wird auf die spezifischen chemischen Anforderungen eingegangen, die für die Schaffung eines effektiven Korrosionsschutzes notwendig sind. Die Norm fördert nicht nur einheitliche Praktiken in der Fertigung, sondern gewährleistet auch, dass die anodisierten Aluminium-Oberflächen optimal für anschließende Lackierungen vorbereitet sind. Die Stärken dieser Norm liegen vor allem in ihrer detaillierten Aufschlüsselung von Verfahren und Qualitätskriterien, die es Herstellern ermöglichen, die Anforderungen an die Oberflächenbehandlung von Aluminium-Werkstoffen präzise zu erfüllen. Dies steigert nicht nur die Effizienz in der Produktion, sondern auch die Zuverlässigkeit der Endprodukte im jeweiligen Anwendungsbereich. Zusätzlich ist die Norm EN 4704:2012 von großer Bedeutung für die Einhaltung der europäischen Standards in der Luft- und Raumfahrtindustrie, was die Wettbewerbsfähigkeit der europäischen Hersteller auf dem globalen Markt unterstützt. Die Festlegung klarer Qualitätsstandards sorgt für ein höheres Maß an Sicherheit und Langlebigkeit der Produkte, die in kritischen Anwendungen eingesetzt werden. Insgesamt bietet die EN 4704:2012 eine solide Grundlage zur Gewährleistung von Qualität und Sicherheit bei der Tartaric-Sulphuric-Acid Anodisierung von Aluminium und Aluminium-Werkstoffen, was nicht nur für die Hersteller sondern auch für die Endverbraucher von enormer Bedeutung ist.
EN 4704:2012 표준은 항공우주 시리즈에서 알루미늄 및 알루미늄 압연 합금의 부식 보호 및 도료 전처리를 위한 타르타르산-황산(TSA) 양극산화 처리에 대한 요구 사항을 정의하고 있습니다. 이 표준은 알루미늄 소재의 특성을 고려하여 설계 및 품질 요구 사항을 제조업체에 제시하는 것을 목적으로 하고 있습니다. 이 표준의 장점 중 하나는 타르타르산-황산 양극산화 처리 방법이 알루미늄과 그 합금의 부식을 효과적으로 방지할 수 있는 최적의 솔루션을 제공한다는 점입니다. 또한, 이 기술은 도료의 부착력을 향상시키는 데 중요한 역할을 하여, 알루미늄 제품의 내구성을 크게 높이는 데 기여합니다. EN 4704:2012는 항공우주 산업에서 요구되는 높은 품질 기준을 명확하게 정의하여, 공급망 내 모든 이해관계자가 일관된 품질을 유지할 수 있도록 합니다. 이는 최종 제품의 신뢰성을 높이고, 산업 전반에 걸쳐 안전성을 강화하는 데 중요한 요소로 작용합니다. 표준의 적용 범위는 여러 제조 공정에서 표준화된 절차를 통해 알루미늄 제품의 품질과 성능을 극대화하는 데 기여합니다. 결과적으로, EN 4704:2012 표준은 알루미늄 및 알루미늄 압연 합금의 TSA 양극산화 처리에 대해 명확하고 체계적인 요구 사항을 제공함으로써, 제조업체와 소비자 모두에게 중요한 가치를 제공하며, 항공우주 분야에서의 부식 방지 및 도료 전처리 기술의 필수 기준으로 자리매김하고 있습니다.
The EN 4704:2012 standard offers a comprehensive framework for Tartaric-Sulphuric-Acid (TSA) anodizing processes in the aerospace sector. Its scope is specifically tailored to delineate the requirements essential for effective corrosion protection and paint pre-treatment for aluminium and wrought alloys. By establishing clear criteria for both design and quality, this standard significantly aids manufacturers in producing high-quality components that meet industry expectations. One of the primary strengths of EN 4704:2012 is its focus on compatibility with both aluminium and various wrought alloys, which makes it relevant across a wide range of applications within the aerospace industry. The standard emphasizes the importance of corrosion resistance, an imperative aspect for aerospace components exposed to harsh environments. This focus not only enhances the longevity of the materials used but also improves overall safety in aviation. Furthermore, the document sets out rigorous quality requirements, which are essential for manufacturers looking to ensure that their anodizing processes adhere to best practices. This aspect contributes directly to the assurance of product performance and reliability, making it a vital reference for those involved in aerospace manufacturing. The relevance of EN 4704:2012 extends beyond mere compliance; it is a pivotal tool for quality assurance in the production of aerospace materials. By adhering to this standard, manufacturers can achieve a higher level of confidence in their processes, thereby fostering trust with end users and regulatory bodies alike. Overall, the EN 4704:2012 standard is an indispensable resource that not only guides the anodizing process but also strengthens the entire aerospace supply chain.
La norme EN 4704:2012 est essentielle dans le domaine des séries aérospatiales, car elle définit précisément les exigences concernant l'anodisation au Tartaric-Sulphuric-Acid (TSA) des alliages d'aluminium et des alliages travaillés. Cette standardisation est particulièrement pertinente pour garantir la protection contre la corrosion et préparer les surfaces à la peinture, deux éléments cruciaux dans l'ingénierie aérospatiale. Le champ d'application de cette norme englobe non seulement les exigences techniques, mais également les critères de qualité qui doivent être respectés par les fabricants. En établissant des directives claires, la norme EN 4704:2012 permet d'uniformiser les procédés de production et assure que les produits finis répondent aux attentes en matière de durabilité et de performance. Parmi les forces de cette norme, on trouve la clarté des exigences qu'elle impose, ce qui facilite l'application pratique par les fabricants industriels. De plus, elle contribue à la minimisation des risques de corrosion, un facteur critique pour la sécurité et la longévité des composants en aluminium utilisés dans l'aviation. En intégrant la préparation des surfaces pour la peinture, la norme permet également d’améliorer l'esthétique et la performance des revêtements appliqués. En somme, la norme EN 4704:2012 s'avère être un outil indispensable qui reflète l'engagement de l'industrie aérospatiale en matière de qualité et de sécurité. Elle souligne l'importance d'une approche standardisée dans le traitement de l'aluminium, ce qui constitue un avantage compétitif significatif pour les fabricants qui cherchent à se conformer aux meilleurs standards du secteur.
EN 4704:2012は、航空宇宙シリーズの標準として、タルタル酸-硫酸（TSA）アノダイジングに関する重要な規定を示しています。この標準は、アルミニウムおよびアルミニウム加工合金の腐食防護および塗装前処理に関する要件を定義しています。TSAアノダイジングのプロセスは、耐食性を高めるだけでなく、後続の塗装プロセスにおける接着性も向上させるため、非常に重要です。 標準の強みは、設計および品質要件を明確に示している点です。製造業者にとって、標準に基づくガイドラインは、品質の一貫性を保ちながら、安全かつ効果的な表面処理を行うための基盤となります。また、EN 4704:2012は、航空宇宙産業に特有の厳しい耐食性要件を満たすために必要な技術的根拠を提供することにより、設計の信頼性を高める役割も果たします。 さらに、この標準は、製品のライフサイクル全体を通じて、環境配慮も考慮されたプロセスを促進します。TSAアノダイジングは、従来のアノダイジング方法よりも環境に優しく、持続可能な製造プロセスを実現するための重要な手段となります。このような背景から、EN 4704:2012は、航空宇宙業界における新しい挑戦に対処するための有用なリソースとなっていると言えます。 総じて、EN 4704:2012は、アルミニウム加工合金におけるタルタル酸-硫酸アノダイジングの標準化を通じて、業界の品質向上と持続可能性推進に寄与しているため、その関連性と重要性は非常に高いと言えるでしょう。
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