SIST EN 1007-6:2009
(Main)Advanced technical ceramic - Ceramic composites - Methods of test for reinforcements - Part 6: Determination of tensile properties of filaments at high temperature
Advanced technical ceramic - Ceramic composites - Methods of test for reinforcements - Part 6: Determination of tensile properties of filaments at high temperature
This European Standard specifies the conditions for measurement of tensile properties of single filament of ceramic fibres at high temperatures in air or inert atmosphere (vacuum or controlled atmosphere). The method applies to continuous ceramic filaments taken from tows, yarns, staple fibre, braids and knitting, that have strain to fracture less or equal to 5 % and show linear elastic behaviour to fracture.
The method does not apply to testing for homogeneity of strength properties of fibres, nor does it assess the effects of volume under stress. Statistical aspects of fibre failure are not included.
Two methods are proposed depending on the temperature of the filament end:
Hot end method: this method allows determination of tensile strength, of Young's modulus and of the stress strain curve.
NOTE 1 Current experience with this technique is limited to 1 300 °C, because of the application temperature of ceramic glue.
Cold end method.
NOTE 2 This method is limited to 1 700 °C in air and 2 000 °C in inert atmosphere because of the limits of furnaces.
Hochleistungskeramik - Keramische Verbundwerkstoffe - Verfahren zur Prüfung der Faserverstärkungen - Teil 6: Bestimmung der Zugeigenschaften von Fasern bei hoher Temperatur
Diese Europäische Norm legt die Bedingungen fest, die für die Bestimmung der Zugeigenschaften einzelner Fäden keramischer Fasern bei hoher Temperatur in Luft oder inerter Atmosphäre (in Vakuum oder einer geregelten Atmosphäre) einzuhalten sind. Das Verfahren gilt für keramische Endlosfasern mit einer Bruchdehnung gleich oder kleiner als 5 % und mit linearem elastischem Verhalten bis zum Bruch, die
Fa¬serbündeln, Fäden, Stapelfasern, Geflechten und Gewirken entnommen werden.
Das Verfahren dient weder zur Überprüfung der Homogenität der Festigkeitseigenschaften der Fasern noch zur Beurteilung der Wirkungen, die von einem unter Spannung stehenden Volumen ausgehen. Statistische Aspekte des Faserbruchs werden nicht erfasst.
In Abhängigkeit von der Temperatur des Faserendes sind zwei Verfahren anwendbar:
- Verfahren mit erhitzten Probenenden: Mit diesem Verfahren sind die Zugfestigkeit, der Youngsche Elastizitätsmodul und die Spannungs Dehnungs Kurve zu bestimmen;.
ANMERKUNG 1 Für dieses Verfahren liegen wegen der maximalen Anwendungstemperatur des Keramikklebstoffs bisher nur Erfahrungen bis zu einer Temperaturgrenze von 1 300 °C vor.
- Verfahren mit kalten Probenenden
ANMERKUNG 2 Die Temperaturgrenzen für dieses Verfahren liegen bedingt durch die verfügbaren Öfen bei Tempera¬turen von 1 700 °C in Luft und 2 000 °C in inerter Atmosphäre.
Céramiques techniques avancées - Céramiques composites - Méthodes d'essai pour renforts - Partie 6 : Détermination des propriétés en traction du filament à haute température
La présente Norme européenne spécifie les conditions de mesure des propriétés en traction d'un filament individuel en fibres céramiques à hautes températures dans l'air ou sous atmosphère inerte (sous vide ou atmosphère contrôlée). La méthode s'applique à des filaments céramiques continus issus de mèches, fils, fibre discontinue, tresses et tricots ayant un allongement à la rupture inférieur ou égal à 5 % et montrant un comportement linéaire élastique jusqu'à la rupture.
La méthode ne permet pas de soumettre à essai l'homogénéité des propriétés de traction des fibres, elle ne permet pas plus d'évaluer les effets de volume sous contrainte. L'aspect statistique de la rupture des fibres n'est pas envisagé.
Deux méthodes sont proposées en fonction de la température de l'extrémité du filament :
Méthode avec mors chauds : cette méthode permet de déterminer la résistance en traction, le module de Young et la courbe contrainte-déformation.
NOTE 1 L'expérience actuelle acquise avec cette technique se limite à 1 300 °C du fait de la température d'application de la colle céramique.
Méthode avec mors froids.
NOTE 2 Cette méthode est limitée à 1 700 °C dans l'air et à 2 000 °C en atmosphère inerte du fait des limites des fours.
Sodobna tehnična keramika - Keramični kompoziti - Preskusne metode za ojačitve - 6. del: Določanje nateznih lastnosti vlaken pri visoki temperaturi
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.XULHochleistungskeramik - Keramische Verbundwerkstoffe - Verfahren zur Prüfung der Faserverstärkungen - Teil 6: Bestimmung der Zugeigenschaften von Fasern bei hoher TemperaturCéramiques techniques avancées - Céramiques composites - Méthodes d'essai pour renforts - Partie 6 : Détermination des propriétés en traction du filament à haute températureAdvanced technical ceramic - Ceramic composites - Methods of test for reinforcements - Part 6: Determination of tensile properties of filaments at high temperature81.060.30Sodobna keramikaAdvanced ceramicsICS:Ta slovenski standard je istoveten z:EN 1007-6:2007SIST EN 1007-6:2009en,fr,de01-januar-2009SIST EN 1007-6:2009SLOVENSKI
STANDARDSIST ENV 1007-6:20071DGRPHãþD
SIST EN 1007-6:2009
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 1007-6November 2007ICS 81.060.30Supersedes ENV 1007-6:2002
English VersionAdvanced technical ceramic - Ceramic composites - Methods oftest for reinforcements - Part 6: Determination of tensileproperties of filaments at high temperatureCéramiques techniques avancées - Céramiquescomposites - Méthodes d'essai pour renforts - Partie 6 :Détermination des propriétés en traction du filament àhaute températureHochleistungskeramik - Keramische Verbundwerkstoffe -Verfahren zur Prüfung der Faserverstärkungen - Teil 6:Bestimmung der Zugeigenschaften von Fasern bei hoherTemperaturThis European Standard was approved by CEN on 13 October 2007.CEN members are bound to comply 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 CEN 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, 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 and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 1007-6:2007: ESIST EN 1007-6:2009
EN 1007-6:2007 (E) 2 Contents Foreword.3 1 Scope.4 2 Normative references.4 3 Terms and definitions.4 4 Principle.6 5 Apparatus.7 5.1 Test machine.7 5.2 Load train.7 5.3 Adhesive.7 5.4 Test chamber.7 5.5 Set-up for heating.7 5.6 Temperature measurement.7 5.7 Data recording system.7 6 Hot end method.8 6.1 General.8 6.2 Test specimens.8 6.3 Test specimen preparation.8 6.4 Number of test specimens.9 6.5 Test procedure.9 6.6 Calculation of results.11 7 Cold end method.14 7.1 General.14 7.2 Method A.14 7.3 Method B.18 Annex A (informative)
Principle of method A.24 Annex B (informative)
Principle of method B.27 Bibliography.29
SIST EN 1007-6:2009
EN 1007-6:2007 (E) 3 Foreword This document (EN 1007-6:2007) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. 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 May 2008, and conflicting national standards shall be withdrawn at the latest by May 2008. 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. This document supersedes ENV 1007-6:2002. 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, 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 and the United Kingdom.
SIST EN 1007-6:2009
EN 1007-6:2007 (E) 4 1 Scope This European Standard specifies the conditions for measurement of tensile properties a of single filament of ceramic fibres at high temperatures in air or inert atmosphere (vacuum or controlled atmosphere). The method applies to continuous ceramic filaments taken from tows, yarns, staple fibre, braids and knitting, that have strain to fracture less than or equal to 5 % and show linear elastic behaviour to fracture. The method does not apply to testing for homogeneity of strength properties of fibres, nor does it assess the effects of volume under stress. Statistical aspects of fibre failure are not included. Two methods are proposed depending on the temperature of the filament end: Hot end method: this method allows determination of tensile strength, of Young's modulus and of the stress strain curve. NOTE 1 Current experience with this technique is limited to 1 300 °C, because of the application temperature of ceramic glue. Cold end method. NOTE 2 This method is limited to 1 700 °C in air and 2 000 °C in inert atmosphere because of the limits of furnaces. 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, the latest edition of the referenced document (including any amendments) applies. EN 1007-3, Advanced technical ceramics — Ceramic composites — Methods of test for reinforcement — Part 3: Determination of filament diameter and cross-section area EN 1007-4, Advanced technical ceramics — Ceramic composites — Methods of test for reinforcement — Part 4: Determination of tensile properties of filaments at ambient temperature EN ISO 7500-1, Metallic materials - Verification of static uniaxial testing machines - Part 1: Tension/compression testing machines - Verification and calibration of the force-measuring system (ISO 7500-1:2004) EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005) EN 60584-1, Thermocouples — Part 1: Reference tables (IEC 60584-1:1995) EN 60584-2, Thermocouples — Part 2: Tolerances (IEC 60584-2:1982 + A1:1989) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 test temperature T temperature of the filament at the centre of the gauge length SIST EN 1007-6:2009
EN 1007-6:2007 (E) 5 3.2 Lengths 3.2.1 gauge length Lo initial distance between two reference points on the filament, where the temperature variation is within 20 °C at test temperature 3.2.2 test specimen length Lf initial distance between the gripped ends of the filament 3.2.3 uniformly heated length Lh length of the heated zone at the test temperature, where the temperature variation is within 20 °C (see Figure A.2) 3.2.4 gradient zone length Ld length of each part of the test specimen where the temperature decreases from the temperature at the end of the uniformly heated length to room temperature (see Figure A.2) 3.2.5 room temperature zone length Lc length of each part of the test specimen where the temperature is equal to room temperature 3.3 initial cross-section area Ao initial cross-section area of the filament within the gauge length determined at room temperature 3.4 maximum tensile force Fm highest recorded tensile force on the test specimen when tested to failure 3.5 tensile stress σσσσ tensile force supported by the test specimen divided by the initial cross-section area 3.6 tensile strength σσσσm ratio of the maximum tensile force to the initial cross-section area 3.7 longitudinal deformation ∆∆∆∆L increase of the gauge length during the tensile test 3.8 Compliance 3.8.1 total compliance Ct reciprocal of the slope in the linear part of the force/displacement curve SIST EN 1007-6:2009
EN 1007-6:2007 (E) 6 3.8.2 load train compliance Cl ratio of the force displacement excluding any test specimen contribution to the corresponding force during the tensile test 3.8.3 gradient zone compliance Cd ratio of the test specimen elongation in the temperature gradient zone length Ld to the corresponding force during the tensile test 3.8.4 cold zone compliance Cc ratio of the test specimen elongation at room temperature Lc to the corresponding force during the tensile test 3.8.5 hot zone compliance Ch ratio of the test specimen elongation in the uniformly heated length Lh to the corresponding force during the tensile test 3.9 strain εεεε ratio of the longitudinal deformation to the gauge length 3.10 fracture strain εεεεm strain at failure of the test specimen 3.11 elastic modulus E slope of the linear part of the tensile stress-strain curve 4 Principle A ceramic filament is heated to the test temperature and loaded in tension. The test is performed at constant force/displacement rate up to failure. Force and cross-head displacement are measured and recorded simultaneously. When required, the elongation is derived from the cross-head displacement using a compliance correction. The test duration is limited to reduce time dependent effects. Subjecting the whole length of a fibre to temperatures well above 1 000 °C makes it difficult to fix the ends of the specimen into appropriate temperature proof extensions. In high temperature cold end tests this problem is avoided by keeping the junction at the ends of the test specimen at room temperature, allowing organic resins to be used as in the room temperature tests (EN 1007-4). Two methods can thus be used: one consists of heating the filament over its total length (hot end method); one consists of heating only the central part of the filament (cold end method). SIST EN 1007-6:2009
EN 1007-6:2007 (E) 7 5 Apparatus 5.1 Test machine The machine shall be equipped with a system for measuring the force applied to the test specimen. The system shall conform to grade 1 in accordance with EN ISO 7500-1. The machine shall be equipped with a system for measuring the force displacement. The accuracy of the measurement shall be better than 1 µm. 5.2 Load train The grips shall align the specimen with the direction of the force. Slippage of the filament in the grips shall be prevented. The load train performance including the alignment system and the force transmitting system shall not change because of heating. 5.3 Adhesive Use a suitable adhesive for affixing the filament to the ends of the grip, such as epoxy resin, cement or sealing wax. 5.4 Test chamber 5.4.1 General When testing under inert conditions, a gastight chamber allows proper control of the test environment during the test. The installation shall be such that the variation of the load due to the variation of pressure is less than 1 % of the scale of the load cell being used. 5.4.2 Gas atmosphere The gas atmosphere shall be chosen depending on the material to be tested and on the test temperature. The level of pressure shall be chosen depending on the material to be tested, on the test temperature and on the type of gas. 5.4.3 Vacuum chamber The level of vacuum shall not induce chemical and/or physical instabilities of the filament material. 5.5 Set-up for heating The set-up for heating shall be constructed in such a way that the variation of temperature within the gauge length is less than 20 °C at test temperature. 5.6 Temperature measurement Thermocouples shall comply with EN 60584-1 and EN 60584-2.
Alternatively, pyrometers or thermocouples which are not covered by EN 60584-1 and EN 60584-2, but which are appropriately calibrated, can be used. 5.7 Data recording system Calibrated recorders may be used to record force-displacement curves. The use of a digital data recording system combined with an analogue recorder is recommended. SIST EN 1007-6:2009
EN 1007-6:2007 (E) 8 6 Hot end method 6.1 General In high temperature the test specimen strain can be determined in simple analogy to the room temperature method assuming that the test specimen sees isothermal conditions along its whole length. According to this hypothesis, the gauge length L0 is equal to the test specimen length Lf. 6.2 Test specimens Specimens with a gauge length of 25 mm shall be used to establish the force-displacement curves. Specimens with a gauge length of 10 mm and 40 mm shall be used to determine the load train compliance Cl. The tolerance on the gauge length is ± 1 mm. 6.3 Test specimen preparation Extreme care shall be taken during test specimen preparation to ensure that the procedure is repeatable from test specimen to test specimen and to avoid handling damage. NOTE As an example to prevent damage during test specimen manipulation and mounting, the assembly of test specimen and alumina tubes is maintained straight by an extra alumina rod, as shown in Figure 1.
key 1 alumina tubes 2 temporary screw attachment 3 test specimen 4 high temperature joints between the test specimen and the alumina tubes 5 alumina rod Figure 1 — Test specimen assembly SIST EN 1007-6:2009
EN 1007-6:2007 (E) 9 6.4 Number of test specimens For each test condition, five valid test results at a gauge length of 25 mm, are required. For the determination of strain related properties, three additional tests at each gauge length of 10 mm and 40 mm are required in order to establish load-train compliance, CL. NOTE 1 If a statistical evaluation is required, the number of test specimens at a gauge length of 25 mm should be in accordance with EN 843-5. NOTE 2 A compliance determination is not required if only strength needs to be determined. 6.5 Test procedure 6.5.1 Test set-up: determination of the temperature profile The following determinations shall be carried out under actual test conditions. Prior to testing, the temperature profile inside the furnace shall be established over the temperature range of interest. This shall be done by measuring the temperature at a minimum of three locations that correspond to the ends and the centre of the maximum gauge length. NOTE 1 When the type of specimen assembly described in Figure 1 is used, the temperature profile may be determined inside the furnace at the end and at mid-way between the tubes positioned at the distance corresponding to the maximum gauge length and without the filament mounted. During a series of tests, the test temperature is determined indirectly from the temperature indicated by the temperature control device. The relation between the control temperature and the test temperature is established over the range of temperature of interest. NOTE 2 Usually the determination of the temperature profile and the relation between control temperature and test temperature are established simultaneously. 6.5.2 Test set-up: other considerations 6.5.2.1 General The dimension of the filament varies with the temperature and the variation is very difficult to measure. 6.5.2.2 Determination of the gauge length, L0 The gauge length is measured to an accuracy of ± 0,1 mm at room temperature. 6.5.2.3 Determination of the initial cross-section area, A0 The filament diameter and thus the initial cross-section area at test temperature, is measured at room temperature in accordance with EN 1007-3. NOTE 1 In principle, the initial cross-section area is determined on the filament to be tested. In practice, this can be achieved by sampling the lengths to be tested from a single filament at intermittent locations and using the parts in between for diameter measurement. This assumes that for the lengths of fibres to be tested, the diameter does not vary significantly with the length. NOTE 2 An alternative method consists of measuring the filament cross-section after fracture from a transverse cross-section taken from the part of the grips still containing embedded fibre. In this case, care is taken not to damage the fibre during preparation. SIST EN 1007-6:2009
EN 1007-6:2007 (E) 10 6.5.3 Testing technique 6.5.3.1 General Follow the chronological steps. 6.5.3.2 Zero the load cell 6.5.3.3 Specimen mounting Mount the specimen in the load train with its longitudinal axis coinciding with that of the test machine. Care shall be taken not to induce torsional loads or surface damage to the filament. The position of the gauge length relative to the furnace shall be identical to that previously used in 6.5.1. 6.5.3.4 Setting of the controlled atmosphere When testing in inert gas, air and water vapour shall be removed before setting the inert atmosphere. This can be done by establishing vacuum (below 10 Pa) in the enclosure, or by circulating inert gas. When testing under vacuum, the vacuum level shall be according to 5.4.3. NOTE In view of the extreme oxidation sensitivity of some of the filament material, conventional flushing of the test chamber might not be sufficient to reduce the oxygen level below acceptable limits. 6.5.3.5 Heating of test specimen Raise the test specimen temperature to the required test temperature and maintain this test temperature for a short period to allow for temperature stabilisation. The test specimen temperature is the furnace temperature. Ensure that the test specimen stays in the initial state of stress during heating. 6.5.3.6 Measurements Record temperature. Record vacuum or gas pressure if applicable. Set the cross-head speed. Record the force versus force/cross-head displacement curve up to failure. Cool down until the risk of degradation is removed before opening the test chamber. 6.5.3.7 Test validity The following circumstances invalidate the test: failure to specify and record test conditions; any slippage in the load train as evidenced by a drop in the force/displacement curve, before reaching the maximum tensile force; any deviation from linearity in the load/cross-head displacement curve after the initial slack has been taken up. The following circumstance invalidates only the strength and stress to failure: failure at the grip(s): see Figure 2. SIST EN 1007-6:2009
EN 1007-6:2007 (E) 11
key 1 rupture at the grips : rupture not valid 2 valid rupture Figure 2 — Rupture at the grips 6.6 Calculation of results 6.6.1 Calculation of the load train compliance, Cl The load train compliance is determined at each test temperature. NOTE This is because some of the contributions to the load train compliance (for example the cement used for fixing the filament) may vary with temperature. Calculate the total compliance Ct for the tests at each of the gauge lengths from the inverse slope in the linear part of the force/cross-head displacement curve.
For each test, plot the total compliance Ct versus L0/A0. Perform a linear regression analysis of Ct versus L0/A0 and determine the load train compliance Cl from the intercept with the ordinate axis (Figure 3). SIST EN 1007-6:2009
EN 1007-6:2007 (E) 12
key 1 total compliance, Ct
(mm/N) 2 Lo = 10 mm 3 Lo = 25 mm 4 Lo = 40 mm 5 Lo/Ao (mm-1) Figure 3 — Determination of the load train compliance Cl 6.6.2 Tensile strength Calculate the tensile strength from the following equation: 0mmAF=σ (1) where σm is the filament strength, in megapascals (MPa); Fm is the maximum load, in Newtons (N); A0 is the initial cross-sectional area, in square millimetres (mm2). SIST EN 1007-6:2009
EN 1007-6:2007 (E) 13 6.6.3 Elastic modulus The elastic modulus is calculated from the following equation: 3lt0010)(1A−×−×=CCLE (2) where E is the elastic modulus, in gigapascals (GPa); A0 is the initial cross-sectional area, in square millimetres (mm2); Cl is the load train compliance, in millimetres per Newton (mm.N-1); Ct is the total compliance, in millimetres per Newton (mm.N-1); L0 is the total gauge length, in millimetres (mm). 6.6.4 Tensile strain at failure The tensile strain at failure, εm, is calculated from the following equation: E×=10mmσε (3) where εm is the tensile strain at failure, in %; σm is the tensile strength, in megapascals (MPa); E is the elastic modulus, in gigapascals (GPa). 6.6.5 Test report The report shall be in accordance with the reporting provisions of EN ISO/IEC 17025 and shall contain at least the following information: a) name and address of testing establishment; b) date of test; c) on each page, a unique report identification and page number; d) customer name and address; e) reference to this standard, i.e. determined in accordance with EN 1007-6:2007; f) authorising signature; g) any deviation from the method described, with appropriate validation, i.e. demonstrated to be acceptable to the parties involved; h) description of the equipment used; SIST EN 1007-6:2009
EN 1007-6:2007 (E) 14 i) complete identification of the tested filament (manufacturer, type, batch, date of receipt, etc.); j) agreed sampling scheme for selecting test specimen from the batch of material; k) method employed for determination of the filament diameter, and average filament diameter; l) number of tests carried out and the number of valid results obtained; m) for each test specimen, the gauge length expressed in millimetres; n) heating rate, temperature of test and displacement rate; o) individual values of tensile strength and strain to failure, the average tensile strength and strain to failure, and the average elastic modulus; p) details of any aspect of experimental procedure which might influence the results; q) comments on the test or test results. 7 Cold end method
7.1 General Two methods are presented, both using a change in specimen compliance in order to eliminate the parasitic contributions to the measured total elongation. 7.2 Method A 7.2.1 Principle of the method The principle of this method is summarised in Annex A. 7.2.2 Test specimens Specimen with a total length Lf1 greater than that of the sum of the uniformly heated length Lh (Lh ≥ 25 mm) and twice the gradient length Ld (Lf > Lh + 2 x Ld) shall be used to establish the force-displacement curves. Specimens of a total length Lf2 = Lf1 + 10 mm and Lf3 = Lf1 + 20 mm shall be used to determine the load train compliance. 7.2.3 Test specimen preparation Extreme care shall be taken during specimen preparation to ensure that the procedure is repeatable from specimen to specimen and to avoid handling damage. 7.2.4 Number of test specimens For each test condition, five valid test results at test specimen length Lf1 are required. For the determination of strain related properties, three additional tests at Lf2 and three additional tests at Lf3 are required to establish load train compliance Cl. NOTE 1 If a statistical evaluation is required, the number of test specimens at any of the above total lengths should be in accordance with EN 843-5. NOTE 2 A compliance determination is not required if only strength needs to be determined. SIST EN 1007-6:2009
EN 1007-6:2007 (E) 15 7.2.5 Test procedure 7.2.5.1 Test set-up: determination of the temperature profile of the furnace and determination of the uniformly heated length Lh The following determinations shall be carried out under actual test conditions. Prior to testing, the temperature profile inside the furnace shall be established over the temperature range of interest in order to determine the uniformly heated length Lh at each temperature of interest. This shall be done by measuring the temperature at least at 10 locations distributed along the length of the empty furnace. The determination of the uniformly heated length, Lh, critically depends on the accuracy of the temperature profile. Also in this method A, the gauge length L0 is equal to the uniformly heated length Lh. 7.2.5.2 Test set-up: other considerations - Determination of the cross-section area A0 The filament diameter varies with temperature and the variation is very difficult to measure. The filament diameter and thus the cross-sectional area at test temperature shall be measured at room temperature in accordance with EN 1007-3. 7.2.6 Testing technique 7.2.6.1 General Carry out the following in the order given. 7.2.6.2 Load cell Zero the load cell. 7.2.6.3 Specimen mounting Mount the specimen in the load train with its longitudinal axis coinciding with that of the test machine. Care shall be taken not to induce torsional loads or surface damage to the filament
7.2.6.4 Setting of the controlled atmosphere When testing under inert gas, air and water vapour shall be removed before setting the inert atmosphere. This can be done by establishing vacuum (below 10 Pa) in the enclosure, or by circulating inert gas. When testing under vacuum, the vacuum level shall be according to 5.4.3. NOTE In view of the extreme oxidation sensitivity of some of the filament material, conventional flushing of the test chamber might not be sufficient to reduce the oxygen level below acceptable limits. 7.2.6.5 Heating of test specimen Raise the test specimen temperature to the required test temperature and maintain this test temperature for a short period to allow for temperature stabilisation. Ensure that the test specimen stays in the initial state of stress during heating. The test specimen temperature is the furnace temperature. 7.2.6.6 Measurements Record temperature. Record vacuum or gas pressure if applicable. Set the cross-head speed. SIST EN 1007-6:2009
EN 1007-6:2007 (E) 16 Record the force/cross-head displacement curve up to failure. Cool down until the risk of degradation is removed before opening the test chamber. 7.2.6.7 Test validity The following circumstances invalidate the test: failure to specify and record test conditions; any slippage in the load train as evidenced by a drop in the force/displacement curve, before reaching the maximum tensile force; any deviation from linearity in the load/cross-head displacement curve after the initial slack has been taken up. The following circumstance invalidates only the determination of the strength and strain to failu
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