1、BRITISH STANDARDBS EN 3976:2006Aerospace series Titanium and titanium alloys Test method Chemical analysis for the determination of hydrogen contentThe European Standard EN 3976:2006 has the status of a British StandardICS 49.025.30g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51
2、g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 3976:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2007 BSI 2007ISBN 978 0 580 50085 5N
3、ational forewordThis British Standard was published by BSI. It is the UK implementation of EN 3976:2006.The UK participation in its preparation was entrusted by Technical Committee ACE/61, Metallic materials for aerospace purposes, to Panel ACE/61/-/49, Titanium and its alloys.A list of organization
4、s represented on ACE/61/-/49 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.Compliance with a British Standard cannot confer immunity from legal obligations.Amendme
5、nts issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 3976December 2006ICS 49.025.30English VersionAerospace series - Titanium and titanium alloys - Test method -Chemical analysis for the determination of hydrogen contentSrie arospatiale - Titane et alli
6、ages de titane - Mthodedessai - Analyse chimique pour dtermination de la teneuren hydrogneLuft- und Raumfahrt - Titan und Titanlegierungen -Versuchsmethode - Chemische Analyse zur Bestimmungdes WasserstoffanteilsThis European Standard was approved by CEN on 18 October 2006.CEN members are bound to c
7、omply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Se
8、cretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the offi
9、cialversions.CEN members are the national standards bodies of Austria, Belgium, 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,
10、 Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members
11、.Ref. No. EN 3976:2006: E2 Contents Page Foreword3 Introduction .4 1 Scope 4 2 Normative references 4 3 Terms and definitions .5 4 Health and safety .5 5 Principle5 6 Testing requirements 6 7 Test report 10 Annex A (informative) Solid State Hot Extraction under Vacuum Method11 EN 3976:20063 Foreword
12、 This document (EN 3976:2006) 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
13、 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 June 2007, and conflicting national standards shall be with
14、drawn at the latest by June 2007. 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, t
15、he national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Pol
16、and, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN 3976:20064 Introduction This standard is part of the series of EN metallic material standards for aerospace applications. The general organization of this series is described in EN 4258. 1 Scope This st
17、andard specifies the requirements for chemical analysis using Inert Gas Fusion Thermal Conductivity Method for the determination of the hydrogen content of titanium and titanium alloys for aerospace applications. The method applies to hydrogen contents ranging from several micrograms per gram to sev
18、eral hundreds of micrograms per gram. It shall be applied when referred to in the EN technical specification or material standard unless otherwise specified on the drawing, order or inspection schedule. NOTE The absolute method not used in routine inspection is solid state hot extraction under vacuu
19、m followed by measurement of volume and pressure. Due to its complexity, it is only summarized in Annex A. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, t
20、he latest edition of the referenced document (including any amendments) applies. ISO Guide 30:1992, Terms and definitions used in connection with reference materials. ISO Guide 31, Reference materials Contents of certificates and labels. ISO Guide 35, Reference materials General and statistical prin
21、ciples for certification. EN 2003-10, Aerospace series Titanium and titanium alloys Test methods Part 10: Sampling for determination of hydrogen content. 1)EN 4258, Aerospace series Metallic materials General organization of standardization Links between types of EN standards and their use. EN 4259,
22、 Aerospace series Metallic materials Definition of general terms. 1)1) Published as ASD Prestandard at the date of publication of this standard. EN 3976:20065 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 general terms definition, see EN 42
23、59 3.2 certified reference material (C.R.M.) definition, see ISO Guide 30 4 Health and safety Resources, test pieces, test samples, test materials, test equipment and test procedures shall comply with the current health and safety regulations/laws of the countries where the test is to be carried out
24、. Where materials and/or reagents which may be hazardous to health are specified, appropriate precautions in conformity with local regulations and/or laws shall be taken. 5 Principle 5.1 General The test consists of thermally decomposing the hydrogenated compounds (mostly as metallic hydrides) prese
25、nt in the titanium or titanium alloys. The degassed hydrogen is sent, in a stream of supporting inert gas, into the detection system (thermal conductivity cell) which allows a quantitative measurement of hydrogen content (comparative). Two extraction modes are considered, with respect to the use (or
26、 not) of a melting flux. (Table 1). Table 1 Method Extraction Mode Temperature Supporting Gas 1 With flux 1 800 C Nitrogen or Argon 2 Without flux 2 100 C Argon 5.2 Method 1 The role of melting flux is to liquefy the mixture (thus facilitating the gas extraction) and to avoid an eventual formation o
27、f nitrides. Fusion is performed in a graphite crucible at a temperature of around 1 800 C: either in a nitrogen supporting gas which allows the nitrogen in the sample to be disregarded with the carbon monoxide which, with the nitrogen, has a very small difference in conductivity. (The excess of carb
28、on and the temperature at which melting is performed prevents any carbon dioxide from forming; it is necessary, however, to foresee a way of trapping small quantities of this gas eventually present by using, for example, a molecular sieve); or in an argon supporting gas which prevents nitrides formi
29、ng and results in a better sensitivity since argon has a greater difference in conductivity compared to hydrogen. A separation of nitrogen and carbon oxides is necessary as well as, in the case of using a high frequency furnace, an adapted frequency to avoid discharges by ionization. EN 3976:20066 5
30、.3 Method 2 Fusion is performed in a graphite crucible at a temperature of around 2 100 C and shall be carried out in an argon supporting gas (nitrogen in this case would cause formation of nitrides). 6 Testing requirements 6.1 Resources 6.1.1 Equipment There are numerous models of apparatus but the
31、y all generally include the following elements: Device for introducing samples; Heating device (induction furnace or resistance furnace); Sweeping system using supporting gas; System for separating gases (if necessary); Thermal conductivity cell. Where a high frequency furnace is used with an argon
32、supporting gas, the frequency shall be adapted to avoid discharges by ionization. 6.1.2 Materials/Reagents 6.1.2.1 Certified Reference Materials (titanium base alloys with certified hydrogen content) According to ISO Guides 31 and 35 these C.R.Ms. should be produced by a certifying body, traceable t
33、o S.I. Units by demonstrated methods and accompanied by a certificate. The certified hydrogen content value shall be accompanied by an uncertainty at a stated level of confidence. 6.1.2.2 Reagents During the analysis only reagents of recognised analytical quality shall be used. Nitric acid 20= 1,38
34、g/ml Hydrofluoric acid Aqueous solution at 40 %, 20= 1,13 g/ml 95 % or 96 % (v/v) ethanol Melting flux tin granules Absorbing reagents, separating columns as specified by the manufacturer of the equipment Carbon tetrachloride Diethyl oxide Acetone EN 3976:20067 6.1.2.3 Compressed gases 6.1.2.3.1 Sup
35、porting gases Nitrogen of a purity 99,995 % (N + rare gases) with H2 99,995 % with N 99,9999 % Helium of a purity 99,9999 % 6.1.2.3.3 Gas for pneumatic devices Compressed air “for laboratory use“. 6.1.3 Qualification of personnel Testing to the requirements of this test method shall only be undertak
36、en and/or supervised by personnel who have demonstrated their competence by a suitable education and appropriate training and experience. 6.2 Test samples/test pieces 6.2.1 Location of samples In the case of semi-finished products: as per EN 2003-10. In the case of finished products: as per special
37、agreement and availability. 6.2.2 Sampling method and preparation of test portion Sampling is carried out by machining, in dry conditions, with no lubricant, using tools cleaned with solvents (sawing with a blade, the protecting paint of which has previously been removed by cleaning with solvents an
38、d abrasive paper, drilling, pelleting, excluding hot cropping) in conditions whereby any heating of the metal is avoided as far as possible. NOTE Titanium is easily hydrogenated by the humidity in the air at temperatures above 300 C. Sampling in the form of chips shall only be envisaged in the case
39、of absolute necessity (due to the risks of heating the sample for analysis and the difficulties in introducing it in the analyser). Whatever its surface appearance, the sample for analysis shall be thoroughly cleaned with solvents to eliminate any potential pollutants such as paint, grease, etc. The
40、 procedure is as follows: clean at ambient temperature with a solvent such as carbon tetrachloride, diethyl oxide (ether), acetone ., if trichlorethylene is used, it shall be followed by one of the above solvents, drying in the air at about 60 C or at ambient temperature under a slight vacuum. Furth
41、ermore, on certain semi-finished industrial products, but never on finished products, cleaning may be completed by pickling at ambient temperature for several minutes using the following acid mixture as recommended by work carried out by the European Community Bureau of References: EN 3976:20068 4 v
42、olumes of nitric acid; 1 volume of hydrofluoric acid; Then rinsed three times in water, three times in ethanol and dried in the air at about 60 C or at room temperature in a slight vacuum. As hydrogen content may be affected by this chemical dissolution, an additional pickling may be added in an aci
43、d mixture corresponding to a weight ratio nitric acid/hydrofluoric acid around 15, in order to remove 5 m to 10 m. 6.2.3 Mass of the sample for analysis The necessary mass of the sample for analysis may vary according to the apparatus, but is generally about 250 mg. NOTE It may be necessary to reduc
44、e sampling accordingly depending on the size of the crucibles compatible with certain types of apparatus. Where the method 1 is used, the quantity of melting flux shall be about 15 times greater than that of the titanium alloy. 6.3 Testing procedure 6.3.1 General instructions The detailed procedure
45、depending on the apparatus used is specified on the manufacturers instruction sheet and cannot be described in this standard. Certain general considerations shall nevertheless be recalled. According to the individual characteristics of each type of analyser, the following should be checked: the clea
46、nness and the absence of deposits in the different circuits by obtaining correct and constant values for the various gas deliveries (in the case of apparatus with a supporting gas), the cleanness and effectiveness of the different filters, traps and absorbing systems. It is absolutely necessary to m
47、aintain the same values for the delivery of the supporting gas, for the temperature of the measuring cell and for the intensity applied on the filament of the thermal conductivity cell in the analysing sequence as in the calibration sequence. 6.3.2 Calibration The various apparatuses generally inclu
48、de a calibrating device by injecting one or several known volumes of pure hydrogen (adjusted according to variations in temperature and pressure). These known volumes are delivered from a compressed hydrogen cylinder by a pneumatic system (calibrated “cavities“ and gas slide valves .). This procedur
49、e effectively calibrates the measuring system but does not enable the effectiveness of extraction and the eventual separation of degassed chemical substances to be evaluated. It is therefore essential to complete this procedure by analysing the Certified Reference Materials. If the result differs considerably ( relative 5 %), the analytical conditions shall be changed: quantity of flux powder, setting of the power applied to the furnace, heating time . The use of the result obtained with th
