1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 4704:2012Aerospace series T a r t a r i c - S u l p h u r i c - A c i d anodizing of aluminium and aluminium wrought alloys for corrosion protection and paint pretreatment
2、(TSA)BS EN 4704:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 4704:2012. The UK participation in its preparation was entrusted to TechnicalCommittee ACE/65, Non-metallic materials for aerospace purposes. A list of organizations represented on this committ
3、ee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2012Published by BSI Standards Limited 2012ISBN 978 0 580 76587 2 ICS 49.040 Co
4、mpliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 February 2012.Amendments issued since publicationDate T e x t a f f e c t e dBS EN 4704:2012EUROPEAN STANDARD NO
5、RME EUROPENNE EUROPISCHE NORM EN 4704 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) Srie arospatiale - Anodisation tartrique de laluminium et des alliages
6、daluminium corroys pour protection contre la corrosion et peinture (TSA) Luft- und Raumfahrt - Weinsure-Schwefelsure-Anodisieren (TSA) von Aluminium und Aluminium-Knetlegierungen fr den Korrosionsschutz und zur Vorbehandlung This European Standard was approved by CEN on 23 December 2011. CEN members
7、 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
8、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
9、 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,
10、 Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation
11、 in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 4704:2012: EBS EN 4704:2012EN 4704:2012 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Terms and definitions .44 Principle 55 Requirements .66 Re-anodizing . 107 Qualification Test Report (QTR) 1
12、1Annex A (informative) Whler curves and stress levels Reference fatigue curves . 12Bibliography . 13BS EN 4704:2012EN 4704:2012 (E) 3 Foreword This document (EN 4704:2012) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries an
13、d 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 standa
14、rd, 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. CE
15、N 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,
16、 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. BS EN 4704:2012EN 4704:2012 (E)
17、4 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 referen
18、ces 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
19、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
20、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
21、(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 alloyin
22、g elements (e. g. Cu, Fe, Zn, Si) on the surface of parts after a process step normally after alkaline etching step BS EN 4704:2012EN 4704:2012 (E) 5 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
23、 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 st
24、ep 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
25、 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 proces
26、s 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 su
27、rface 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. BS EN 4704:2012EN 4704:2012 (E) 6 4.2 Limitations All processes that can compromis
28、e 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
29、: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 oxid
30、e layer influences the dimensions of the part and should be considered for close tolerance parts. 5 Requirements 5.1 Technical requirements 5.1.1 Prior to anodizing step: the parts shall be free of oil, grease, marking inks and other surface contaminations; the surface shall be free from precipitati
31、ons or smut from alloying elements or pre-processes indicated by the bright and uniform appearance of the surface; parts/areas that do not require anodizing shall be masked accordingly; mechanically disturbed layer shall be removed either by mechanical or chemical processes; in case of chemical pre-
32、treatment, the final step prior to anodizing shall be acidic pickling, preferably chromate-free; in case of re-anodizing all residuals from the previous anodizing shall be completely removed. 5.1.2 During the anodizing process: the parts shall not be subjected to any tensile, flexure, torsion or oth
33、er stress; the process shall performed such, that parts do not dry between single process steps (pre-treatment, anodizing, etc.). BS EN 4704:2012EN 4704:2012 (E) 7 5.1.3 After the anodizing procedure: parts have to be adequately rinsed with water according to 5.1.4; afterwards, the parts shall be ei
34、ther: dried and painted within 16 h. The parts can be kept in a dry and dust-free atmosphere for 168 h before painting; or sealed to achieve the desired corrosion resistance of the anodic film; appropriate measure should be taken to prevent and to eliminate possible microbiological contaminations of
35、 the rinsing bath, e.g. UV radiation. 5.1.4 Water quality: All water used for preparation of the TSA bath and for the final rinsing step as well as for the sealing process shall be demineralized. The water shall comply with the following requirements: pH value at 25 C : 5,0 to 7,0; total residue mg/
36、l : 20; conductivity S/cm : 20. 5.2 Engineering requirements 5.2.1 Requirements to the anodic film 5.2.1.1 Visual aspects The film shall be free of powdery areas, burnings, blisters and discontinuities such as scratches, ruptures or other damages. 5.2.1.2 Film thickness The thickness of the anodic f
37、ilm shall be in a range of 2 m to 7 m. The thickness of the film can be checked by eddy current method (EN ISO 2360), optical microscope (EN ISO 1463), scanning electronic microscope (SEM), or equivalent examinations. 5.2.2 Corrosion prevention performance of unpainted parts When tested in accordanc
38、e to EN ISO 9227 the anodised and sealed post-treated specimens shall show: less than 2 pits/dm2; no pit shall exceed 0,8 mm in diameter; no patchy dark grey areas (spots, streaks or marks) after an exposure time of minimum 14 days according to EN ISO 9227 for 2024 T351 unclad and 7175 T7351 unclad.
39、 There can also other materials be used if they are defined between the supplier and the customer. The area of 2 mm from the specimen edges and marks shall not be evaluated. BS EN 4704:2012EN 4704:2012 (E) 8 5.2.3 Paint adhesion on anodic film The coating system shall be agreed between the intereste
40、d parties. Test the adhesion in accordance with EN ISO 2409. The damage of painted specimens shall not exceed: class 0 (according to EN ISO 2409) for specimen at initial stage; class 1 (according to EN ISO 2409) for specimen after 14 days of water immersion at (23 2) C. 5.2.4 Corrosion prevention pe
41、rformance of painted parts 5.2.4.1 Filiform corrosion The maximum length of the longest filament shall not exceed 2 mm on either side of the scratches at 40 days of exposure when tested in accordance with EN 3665. Alloy in accordance with 5.2.2. 5.2.4.2 Corrosion resistance There shall not be any co
42、rrosion, blister, extending further than max. 1,25 mm on either side of the scratch at 125 days of exposure when tested in accordance with EN ISO 9227. Alloy in accordance with 5.2.2. 5.2.5 Fatigue Requirements The fatigue specimen shall be manufactured and tested in accordance with EN 6072. All the
43、 fatigue test values shall be plotted on the Whler curves presented in Annex A (mean and minimum curves). at least 50 % of the sample shall be on or above the mean curve; 90 % of the samples shall be above the minimum curve. 5.3 Quality requirements 5.3.1 General requirements All process steps, para
44、meters and tests shall be defined in a process instruction. 5.3.2 Test frequency The details and frequency for permanent and regular quality control checks shall be defined by the quality assurance of the shop considering: the ageing, contamination and the efficiency of the bath; the production rate
45、. After specific events as re-adjustment of refilling of the bathes appropriate performance of the process shall be ensured by quality tests. BS EN 4704:2012EN 4704:2012 (E) 9 5.3.3 Visual aspect of the parts All relevant areas of the parts have to be covered by the anodic film. The anodic film shal
46、l be free of powdery areas, burnings, blisters and discontinuities such as scratches, ruptures or other damages. There shall be no water stains on surfaces to which a coating is to be applied. The parts have to be inspected by naked eyes under constant light conditions. Checking of powdery areas or
47、dusting is made with the help of a white and dry rag, which is slightly rubbed on the part to check. A slight dusting may be accepted so far as the paint appearance is not altered. 5.3.4 Thickness of anodic film The thickness of the film can be checked by eddy current method (EN ISO 2360), optical m
48、icroscope (EN ISO 1463), scanning electronic microscope (SEM), or equivalent examinations. Alternatively 5.3.7 can be applied. 5.3.5 Film weight The film weight shall be 22 mg/dm2when tested. The film weight shall be determined in accordance with EN ISO 2106. Alternatively 5.3.6 can be applied. 5.3.
49、6 Corrosion resistance of anodic film When tested in accordance with EN ISO 9227 the anodized and sealed specimens shall show: less than 2 pits/dm2; no pit shall exceed 0,8 mm in diameter; no patchy dark grey areas (spots, streaks or marks). after an exposure time of minimum 14 days for 2024 T351 unclad and 7175 T7351 unclad. 5.3.7 Sealing quality After rinsing and scrubbing under water with a cotton cloth, the blue discolora
