SIST EN 14425-3:2010
(Main)Advanced technical ceramics - Test methods for determination of fracture toughness of monolithic ceramics - Part 3: Chevron notched beam (CNB) method
Advanced technical ceramics - Test methods for determination of fracture toughness of monolithic ceramics - Part 3: Chevron notched beam (CNB) method
This European Standard provides a test method for fracture toughness determination based on the chevronnotch method. For the purposes of this European Standard, the term monolithic includes particle and whisker reinforced advanced technical ceramics which can be regarded as macroscopically homogeneous. It does not include long-fibre reinforced ceramics.
Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit von monolithischer Keramik - Teil 3: Verfahren für Biegeproben mit Chevron-Kerb (CNB-Verfahren)
Diese Europäische Norm legt ein Prüfverfahren zur Bestimmung der Bruchzähigkeit nach dem Chevron Kerb Verfahren fest. Für die Anwendung dieser Europäischen Norm schließt der Begriff monolithisch partikel- und whiskerverstärkte Hochleistungskeramik ein, die als makroskopisch homogen angesehen werden kann. Das Verfahren gilt nicht für langfaserverstärkte Keramik.
Céramiques techniques avancées - Méthode d'essai de détermination de la ténacité à la rupture des céramiques monolithiques - Partie 3: Méthode de l'éprouvette à entaille en chevron
La présente Norme européenne propose une méthode d'essai visant à déterminer la ténacité à la rupture à l'aide de la méthode à entaille en chevron. Pour les besoins de la présente Norme européenne, le terme monolithique recouvre les céramiques techniques avancées renforcées de particules et de trichites pouvant être considérées comme macroscopiquement homogènes. Il n'inclut pas les céramiques renforcées de longues fibres.
Sodobna tehnična keramika - Preskusne metode za ugotavljanje odpornosti monolitske keramike proti lomljenju - 3. del: Upogibni preskus z zarezo (metoda CNB)
Ta evropski standard zagotavlja preskusno metodo za ugotavljanje odpornosti proti lomljenju na osnovi upogibne metode z zarezo. Za namene tega evropskega standarda izraz monolitski vključuje sodobno tehnično keramiko, ojačano z delci in filamenti, ki se lahko šteje za makroskopsko homogeno. Ne vključuje keramike, ojačane z dolgimi vlakni.
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.UQRVWL&1%Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit von monolithischer Keramik - Teil 3: Verfahren für Biegeproben mit Chevron-Kerb (CNB-Verfahren)Céramiques techniques avancées - Méthode d'essai de détermination de la ténacité à la rupture des céramiques monolithiques - Partie 3: Méthode de l'éprouvette à entaille en chevronAdvanced technical ceramics - Test methods for determination of fracture toughness of monolithic ceramics - Part 3: Chevron notched beam (CNB) method81.060.30Sodobna keramikaAdvanced ceramicsICS:Ta slovenski standard je istoveten z:EN 14425-3:2010SIST EN 14425-3:2010en,fr,de01-september-2010SIST EN 14425-3:2010SLOVENSKI
STANDARD
SIST EN 14425-3:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14425-3
June 2010 ICS 81.060.30 Supersedes CEN/TS 14425-3:2003English Version
Advanced technical ceramics - Test methods for determination of fracture toughness of monolithic ceramics - Part 3: Chevron notched beam (CNB) method
Céramiques techniques avancées - Méthode d'essai de détermination de la ténacité à la rupture des céramiques monolithiques - Partie 3: Méthode de l'éprouvette à entaille en chevron
Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit von monolithischer Keramik - Teil 3: Verfahren für Biegeproben mit Chevron-Kerb (CNB-Verfahren) This European Standard was approved by CEN on 30 April 2010.
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 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 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 and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14425-3:2010: ESIST EN 14425-3:2010
EN 14425-3:2010 (E) 2 Contents Page Foreword .31 Scope .42 Normative references .43 Terms and definitions .44 Principle, significance and use .45 Test apparatus .56 Test pieces .56.1 Material selection .56.2 Test piece dimensions .56.3 Sawn notch .67 Procedure .68 Calculation of results .79 Interferences and errors .810 Reporting .8Bibliography . 14 SIST EN 14425-3:2010
EN 14425-3:2010 (E) 3 Foreword This document (EN 14425-3:2010) 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 December 2010, and conflicting national standards shall be withdrawn at the latest by December 2010. 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 CEN/TS 14425-3:2003. 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 and the United Kingdom. SIST EN 14425-3:2010
EN 14425-3:2010 (E) 4 1 Scope This European Standard provides a test method for fracture toughness determination based on the chevron-notch method. For the purposes of this European Standard, the term monolithic includes particle and whisker reinforced advanced technical ceramics which can be regarded as macroscopically homogeneous. It does not include long-fibre reinforced ceramics. 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 843-1:2006, Advanced technical ceramics — Mechanical properties of monolithic ceramics at room temperature — Part 1: Determination of flexural strength EN 1006, Advanced technical ceramics — Monolithic ceramics — Guidance on the selection of test pieces for the evaluation of properties 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) ISO 3611, Micrometer callipers for external measurement 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 chevron-notch test piece test piece in which a two coplanar saw cuts are made at an angle to each other part way through a test piece to leave a remaining cross-section with a sharp tip from which a crack may be initiated in a controlled or semi-controlled manner 4 Principle, significance and use In the chevron-notched beam method, a crack is generated during the test from a sharp tip resulting when two coplanar notches are cut in a test piece (see Figure 1). This overcomes the need to generate sharp planar cracks before commencing the test.
During the test, the crack front widens as the crack propagates from the tip, resulting in an increase in the force required to maintain growth. Countering this, the test piece becomes more compliant as the crack lengthens, and so the two effects result in a peak load being attained after some distance of propagation. The toughness is determined from the peak force applied. This test method employs the chevron notch in a flexural strength test piece, loaded in four-point bending geometry. The advantage is that it can be performed on standard flexural strength test pieces. SIST EN 14425-3:2010
EN 14425-3:2010 (E) 5 The test is most appropriate for homogeneous isotropic materials, but can be used with care on anisotropic materials subject to the geometry of fracture remaining valid. In materials which are inhomogeneous on the scale of the crack dimensions, a wide scatter of results and the development of invalid non-planar cracks may occur. In addition, the test is valid primarily for materials which do not show rising crack resistance with increasing crack length. Since the crack width progressively increases as propagation occurs, the concurrent presence of rising crack resistance means that the crack front would no longer stay straight but would become convex, producing an uncertainty in the calculated results. It should be noted that this test employs a slowly moving crack. The numerical value for the fracture toughness calculated from this method may not be the same as those from fast crack propagation tests, especially if the susceptibility to subcritical crack growth is significant.
5 Test apparatus 5.1 Flexural strength test apparatus of four-point bending type, in accordance with the requirements in EN 843-1. 5.2 Mechanical testing machine, capable of accurate recording of load/displacement data for loads in the range 0 N to 500 N. The load shall be calibrated in accordance with EN ISO 7500-1. NOTE A stiff loading system (i.e. frame, load cell and fixtures, etc.) is advantageous for this test. The compliance is ideally less than 5 × 10-5 m/N (see [1]). 5.3 Micrometer in accordance with ISO 3611 but measuring to an accuracy of 0,002 mm.
5.4 Calibrated device for measuring dimensions of the cut chevron after fracture, reading to an accuracy of 0,002 mm or better. NOTE This may be achieved by use of an appropriate travelling microscope, or a conventional microscope with a calibrated stage micrometer, or a microscope with a micrometer eyepiece. 5.5 Humidity measuring device for measuring relative humidity to an accuracy of ± 2 %, e.g. those according to ISO 4677. 6 Test pieces 6.1 Material selection Select the material or components from which test pieces are to be machined with reference to the considerations given in EN 1006. 6.2 Test piece dimensions 6.2.1 The test pieces shall preferably be of dimensions as for determination of flexural strength and described in EN 843-1. Alternatively, if availability of material permits, the dimensions may be scaled larger for convenience of machining of the notch. NOTE It is usually advantageous to test coarse-grained or heterogeneous materials in larger test piece sizes because it improves the chances of obtaining a valid test (see 7.9). 6.2.2 The standard size test pieces shall be (3,00 ± 0,15) mm × (4,00 ± 0,15) mm in cross-section, and have a minimum length of 45 mm. The surfaces shall be machined to a flatness of better than 0,01 mm over the test piece length, and opposite pairs of faces shall be parallel to better than 0,01 mm over the test piece length. The section should be visibly rectangular.
NOTE Chamfering in accordance with EN 843-1 is unnecessary for this test. SIST EN 14425-3:2010
EN 14425-3:2010 (E) 6 6.2.3 The test piece surfaces shall be ground to a good quality finish using final grinding with a peripheral wheel of grit size between 320 and 500 mesh grit, using a depth of cut of no more than 0,002 mm for the last 0,04 mm of material removed from each surface. No edge treatment is necessary. NOTE Although a large notch is placed in the test piece, the quality of grinding remains important for dimensional accuracy for registration in cutting the notch and for minimizing residual stresses. 6.3 Sawn notch 6.3.1 The notch is produced by two saw cuts at an appropriate angle to each other as shown in Figure 1. The notch width s
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.UQRVWL&1%Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit von monolithischer Keramik - Teil 3: Verfahren für Biegeproben mit Chevron-Kerb (CNB-Verfahren)Céramiques techniques avancées - Méthode d'essai de détermination de la ténacité à la rupture des céramiques monolithiques - Partie 3: Méthode de l'éprouvette à entaille en chevronAdvanced technical ceramics - Test methods for determination of fracture toughness of monolithic ceramics - Part 3: Chevron notched beam (CNB) method81.060.30Sodobna keramikaAdvanced ceramicsICS:Ta slovenski standard je istoveten z:FprEN 14425-3kSIST FprEN 14425-3:2010en,fr,de01-januar-2010kSIST FprEN 14425-3:2010SLOVENSKI
STANDARD
kSIST FprEN 14425-3:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
FINAL DRAFT
FprEN 14425-3
October 2009 ICS 81.060.30 Will supersede CEN/TS 14425-3:2003English Version
Advanced technical ceramics - Test methods for determination of fracture toughness of monolithic ceramics - Part 3: Chevron notched beam (CNB) method
Céramiques techniques avancées - Méthode d'essai de détermination de la ténacité à la rupture des céramiques monolithiques - Partie 3: Méthode de l'éprouvette à entaille en chevron
Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit von monolithischer Keramik - Teil 3: Verfahren für Biegeproben mit Chevron-Kerb (CNB-Verfahren) This draft European Standard is submitted to CEN members for unique acceptance procedure. It has been drawn up by the Technical Committee CEN/TC 184.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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 Management Centre has the same status as the official 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.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. FprEN 14425-3:2009: EkSIST FprEN 14425-3:2010
FprEN 14425-3:2009 (E) 2 Contents Page Foreword .31 Scope .42 Normative references .43 Terms and definitions .44 Principle, significance and use .45 Test apparatus .56 Test pieces .56.1 Material selection .56.2 Test piece dimensions .56.3 Sawn notch .67 Procedure .68 Calculation of results .79 Interferences and errors .810 Reporting .9Bibliography . 14 kSIST FprEN 14425-3:2010
FprEN 14425-3:2009 (E) 3 Foreword This document (FprEN 14425-3:2009) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. This document is currently submitted to the Unique Acceptance Procedure. This document will supersede CEN/TS 14425-3:2003. kSIST FprEN 14425-3:2010
FprEN 14425-3:2009 (E) 4
1 Scope This European Standard provides a test method for fracture toughness determination based on the chevron-notch method. For the purposes of this European Standard, the term monolithic includes particle and whisker reinforced advanced technical ceramics which can be regarded as macroscopically homogeneous. It does not included long-fibre reinforced ceramics. 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 843-1, Advanced technical ceramics — Mechanical properties of monolithic ceramics at room temperature — Part 1: Determination of flexural strength EN 1006, Advanced technical ceramics — Monolithic ceramics — Guidance on the selection of test pieces for the evaluation of properties 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) ISO 3611, Micrometer callipers for external measurement ISO 4677, Atmospheres for conditioning and testing — Determination of relative humidity 3 Terms and definitions For the purposes of this document, the following term and definition applies. 3.1 chevron-notch test piece test piece in which a two coplanar saw cuts are made at an angle to each other part way through a test piece to leave a remaining cross-section with a sharp tip from which a crack may be initiated in a controlled or semi-controlled manner. 4 Principle, significance and use In the chevron-notched beam method, a crack is generated during the test from a sharp tip resulting when two coplanar notches are cut in a test piece (see Figure 1). This overcomes the need to generate sharp planar cracks before commencing the test.
During the test, the crack front widens as the crack propagates from the tip, resulting in an increase in the force required to maintain growth. Countering this, the test piece becomes more compliant as the crack lengthens, and so the two effects result in a peak load being attained after some distance of propagation. The toughness is determined from the peak force applied. kSIST FprEN 14425-3:2010
FprEN 14425-3:2009 (E) 5 This test method employs the chevron notch in a flexural strength test piece, loaded in four-point bending geometry. The advantage is that it can be performed on standard flexural strength test pieces. The test is most appropriate for homogeneous isotropic materials, but can be used with care on anisotropic materials subject to the geometry of fracture remaining valid. In materials which are inhomogeneous on the scale of the crack dimensions, a wide scatter of results and the development of invalid non-planar cracks may occur. In addition, the test is valid primarily for materials which do not show rising crack resistance with increasing crack length. Since the crack width progressively increases as propagation occurs, the concurrent presence of rising crack resistance means that the crack front would no longer stay straight but would become convex, producing an uncertainty in the calculated results. It should be noted that this test employs a slowly moving crack. The numerical value for the fracture toughness calculated from this method may not be the same as those from fast crack propagation tests, especially if the susceptibility to subcritical crack growth is significant.
5 Test apparatus 5.1 Flexural strength test apparatus of four-point bending type in accordance with the requirements in EN 843-1. 5.2 Mechanical testing machine capable of accurate recording of load/displacement data for loads in the range 0 N to 500 N. The load shall be calibrated in accordance with EN ISO 7500-1. NOTE A stiff loading system (i.e. frame, load cell and fixtures, etc.) is advantageous for this test. The compliance is ideally less than 5 x 10-5 m/N (see [1]). 5.3 Micrometer in accordance with ISO 3611 but measuring to an accuracy of 0,002 mm.
5.4 Calibrated device for measuring dimensions of the cut chevron after fracture, reading to an accuracy of 0,002 mm or better. NOTE This may be achieved by use of an appropriate travelling microscope, or a conventional microscope with a calibrated stage micrometer, or a microscope with a micrometer eyepiece. 5.5 Humidity measuring device for measuring relative humidity to an accuracy of ± 2 %, e.g. those according to ISO 4677. 6 Test pieces 6.1 Material selection Select the material or components from which test pieces are to be machined with reference to the considerations given in EN 1006. 6.2 Test piece dimensions 6.2.1 The test pieces shall preferably be of dimensions as for determination of flexural strength and described in EN 843-1. Alternatively, if availability of material permits, the dimensions may be scaled larger for convenience of machining of the notch. NOTE It is usually advantageous to test coarse-grained or heterogeneous materials in larger test piece sizes because it improves the chances of obtaining a valid test (see 7.9). 6.2.2 The standard size test pieces shall be 3,00 ± 0,15 mm x 4,00 ± 0,15 mm in cross-section, and have a minimum length of 45 mm. The surfaces shall be machined to a flatness of better than 0,01 mm over the test kSIST FprEN 14425-3:2010
FprEN 14425-3:2009 (E) 6 piece length, and opposite pairs of faces shall be parallel to better than 0,01 mm over the test piece length. The section should be visibly rectangular.
NOTE Chamfering in accordance with EN 843-1 is unnecessary for this test. 6.2.3 The test piece surfaces shall be ground to a good quality finish using final grinding with a peripheral wheel of grit size between 320 and 500 mesh grit, using a depth of cut of no more than 0,002 mm for the last 0,04 mm of material removed from each surface. No edge treatment is necessary. NOTE Although a large notch is placed in the test piece, the quality of grinding remains important for dimensional accuracy for registration in cutting the notch and for minimizing residual stresses. 6.3 Sawn notch 6.3.1 The notch is produced by two saw cuts at an appropriate angle to each other as shown in Figure 1. The notch width shall be less than 0,20 mm at the surface, and the notch
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