1、Aerospace series - Trivalent chromium based chemical conversion coatings for aluminium and aluminium alloysBS EN 4729:2017BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 4729 September 2017 ICS 25.220.99 English Ve
2、rsion Aerospace series - Trivalent chromium based chemical conversion coatings for aluminium and aluminium alloysSrie arospatiale - Conversion chimique au chrome trivalent de laluminium et des alliages daluminium Luft- und Raumfahrt - Chrom-(III)-basierte chemische Konversionsberzge fr Aluminium und
3、 Aluminiumlegierungen This European Standard was approved by CEN on 14 May 2017. 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 b
4、ibliographical 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 res
5、ponsibility 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 R
6、epublic 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 COMIT EUROP
7、EN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2017 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 4729:2017 ENational forewordThis British Standard is the UK im
8、plementation of EN 4729:2017.The UK participation in its preparation was entrusted to Technical Committee ACE/65, Non-metallic materials for aerospace purposes.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to inclu
9、de all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 97651 3ICS 25.220.99Compliance with a British Standard cannot confer immunity from legal obligations.This Bri
10、tish Standard was published under the authority of the Standards Policy and Strategy Committee on 30 September 2017.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS EN 4729:2017EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 4729 September 2017 ICS 25.220.99 En
11、glish Version Aerospace series - Trivalent chromium based chemical conversion coatings for aluminium and aluminium alloysSrie arospatiale - Conversion chimique au chrome trivalent de laluminium et des alliages daluminium Luft- und Raumfahrt - Chrom-(III)-basierte chemische Konversionsberzge fr Alumi
12、nium und Aluminiumlegierungen This European Standard was approved by CEN on 14 May 2017. 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 lis
13、ts 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
14、 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 Yu
15、goslav 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 COM
16、IT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2017 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 4729:2017 EBS EN 4729:2017EN 4729:2017 (E) 2 Contents
17、Page European foreword 3 1 Scope 4 2 Purpose of process . 4 3 Normative references 4 4 Terms and definitions . 4 5 Applicability and limitations of the process . 5 6 Classification . 5 7 Requirements . 5 8 Main technical engineering requirements 8 9 Quality requirements 10 10 Quality assurance 12 11
18、 Health, safety and environmental aspects . 12 12 Designation . 13 BS EN 4729:2017EN 4729:2017 (E) 3 European foreword This document (EN 4729:2017) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries and votes carried out in a
19、ccordance 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 publicatio
20、n of an identical text or by endorsement, at the latest by March 2018, and conflicting national standards shall be withdrawn at the latest by March 2018. 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 respon
21、sible 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, Finlan
22、d, 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. BS EN 4729:2017EN 4729:201
23、7 (E) 4 1 Scope This European Standard specifies trivalent chromium based chemical conversion coatings for aluminium and aluminium alloys. It covers the application by bath but also by touch-up. It doesnt give complete in-house process instructions; these shall be given in the manufacturers detailed
24、 process instructions. 2 Purpose of process The aim of the trivalent chromium based chemical conversion coatings is to increase corrosion resistance, to improve the adhesion of paints and varnishes and to ensure electrical conductivity. Coatings are also suitable for the repair of mechanically damag
25、ed anodic coatings. 3 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
26、(including any amendments) applies. EN 4707, Aerospace series Acid pickling of aluminum and aluminum alloy without hexavalent chromium 1)EN 9100, Quality Management Systems Requirements for Aviation, Space and Defence Organizations EN ISO 2409, Paints and varnishes Cross-cut test EN ISO 2812-2, Pain
27、ts and varnishes Determination of resistance to liquids Part 2: Water immersion method EN ISO 3892, Conversion coatings on metallic materials Determination of coating mass per unit area Gravimetric methods EN ISO 9227, Corrosion tests in artificial atmospheres Salt spray tests 4 Terms and definition
28、s For the purposes of this document, the following terms and definitions apply. 4.1 batch unless otherwise specified, it comprises parts of the same type (shape, size, material), processed at the same time in the same bath 4.2 substrate material upon which a coating is directly applied, in the case
29、of a single or first coating, the substrate is the basis metal and for a subsequent coating, the intermediate coating is the substrate 1) Published as ASD-STAN Prestandard at the date of publication of this standard by AeroSpace and Defence industries Association of Europe - Standardization (ASD-STA
30、N) (www.asd-stan.org) BS EN 4729:2017EN 4729:2017 (E) 5 4.3 pit substrate corrosion defect at which the conversion coating is penetrated Note 1 to entry: Typical characteristics of corrosion pits are: rounded or irregular or elongated geometry, comet tail or line or halo that emerges from the cavity
31、, some corrosion by-products inside pits (on aluminium test samples the by-product may be granular, powdery or amorphous and white, grey or black in colour). Note 2 to entry: To be considered a corrosion pit, a surface cavity must exhibit at least two of the above characteristics. 5 Applicability an
32、d limitations of the process This standard applies whenever referenced. Parts with features that may trap treatment solutions shall be subjected to additional rinsing operations to ensure removal of treatment solutions. Chemical conversion treatment shall not be applied if removal of treatment solut
33、ion cannot be assured. Chemical conversion coatings shall not be applied to parts before bonding or welding. The maximum in service temperature of the chemical conversion coatings, is 100 C. 6 Classification 6.1 Coating weight For trivalent chromium base conversion coating, the mass per unit area sh
34、ould be ranged from 0,2 g/m2to 0,9 g/m2. 6.2 Materials Category 1: Aluminium alloy 1 000, 5 000 and 6 000 series, Category 2: Aluminium alloy 2 000 and 7 000 series, Category 3: Aluminium alloy castings. For cladded aluminium alloys, the clad is considered as the material. 7 Requirements 7.1 Process
35、 requirements 7.1.1 Information for the processor categories of materials; substrate standard reference and heat treatment; areas to be coated; specification for testing on parts and/or samples; criticality of parts. BS EN 4729:2017EN 4729:2017 (E) 6 7.1.2 Condition of parts prior to processing weld
36、ing, soldering/brazing, mechanical operations and heat treatments shall have been completed. the parts shall be free of oil, grease, marking inks and other surface contaminations; mechanically disturbed layer shall be removed either by mechanical or chemical processes; in case of re-treatment all re
37、siduals from the previous coating shall be completely removed. Tooling The tools and metal masking tooling must be protected against corrosion, and/or free of corrosion or any other damage which may be detrimental to the treatment during use. The part racks and tools must be designed and set up in s
38、uch a manner as to: avoid any retention of air or treatment solution in the parts, facilitate neutralization and removal of solutions during rinsing operations, avoid during the treatment any accidental contact between the parts to be treated and the tank equipment, and between the different parts.
39、The parts shall be previously degreased prior to masking. Component areas which must not be coated shall be masked with suitable material. 7.1.3 Pre-treatment The pre-treatment phase shall not result in critical deterioration of dimensions, surface finish and mechanical properties of parts. For conv
40、ersion coating applied by touch up process or following vapor deposited aluminium (IVD or PVD) a mechanical pre-treatment is allowed. Cleaning Surface preparation means any method able to completely eliminate all surface contaminations. Pickling It shall not cause pitting, intergranular corrosion or
41、 any alterations to the metallurgical characteristics or mechanical strength of the material. Chemical conversion coating must be performed immediately after pickling (in accordance with aluminium and aluminium alloys pickling standard EN 4707). Rinsing bath See 7.1.4. BS EN 4729:2017EN 4729:2017 (E
42、) 7 7.1.4 Rinsings The parts shall be rinsed thoroughly, it is recommended that the final rinsing of each step of overall process has to be carried out in deionized water. The supplied deionised water shall comply with the following requirements: pH value at 25 C: 5.0 to 8.0 total residue mg/l: 5 co
43、nductivity nullS/cm: 20 For touch-up application, rinsing is optional, according to product specification. 7.1.5 Treatment The parts are immersed in a still or agitated bath or treated by spraying or by touch-up (RTU, gel, stick). A commercial product may be used according to the manufacturers instr
44、uctions. During the bath application process: distance between parts shall be adapted in order to avoid impacts. parts shall be fully immersed, in such a way that all air can escape. during emersion the bath fluid shall run off from all areas and cavities. tubes shall be placed in the bath in such a
45、 way that the bath fluid can rise in the bath, expelling all the air. If not, the bath fluid shall then be drawn in or pump through. the process shall be performed in such a way that parts do not dry between single process steps (pre-treatment, treatment, post-treatment). the parameters (temperature
46、, time) shall be adapted to the material and its requirements in accordance with manufacturer instructions. It is recommended to handle the parts after treatment and after each post-treatment step with gloves. a rinsing step shall be performed according 7.1.4. parts shall be stored under clean and d
47、ry conditions. Drying may be carried out with dry, oil-free air at ambient temperature or at max. 60 C. 7.1.6 Post-treatment Optional chemical treatment can be applied to improve corrosion resistance performance In case of optional chemical treatments the drying shall not be applied. A commercial pr
48、oduct may be used according to the manufacturers instructions. See 7.1.5 for process recommendation. BS EN 4729:2017EN 4729:2017 (E) 8 Paints or varnishes It is recommended to apply the primer or the varnish coat 48 h maximum after treatment or according to specific purchaser requirement. In case th
49、e time is exceeded, an appropriate storage and visual inspection (homogeneous appearance and free from pitting, stains and contamination) should be carried out after the conversion coating process. In case of heterogeneous aspect, pitting, stains and contamination reprocessing of parts depends on the material and may only be carried out following confirmation and requirements by the manufacturer. 7.1.7 Removal of the coating The stripping shall be carried out following conf
