EN 843-6-2009 en Advanced technical ceramics - Mechanical properties of monolithic ceramics at room temperature - Part 6 Guidance for fractographic investigation《先进技术陶瓷 环境温度单片陶瓷的力学.pdf

1、BS EN 843-6:2009 ICS 81.060.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Advanced technical ceramics Mechanical properties of monolithic ceramics at room temperature Part 6: Guidance for fractographic investigationThis British Standard was published unde

2、r the authority of the Standards Policy and Strategy Committee on 31 January 2010 BSI 2010 ISBN 978 0 580 63845 9 Amendments/corrigenda issued since publication Date Comments BS EN 843-6:2009 National foreword This British Standard is the UK implementation of EN 843-6:2009. It supersedes DD CEN/TS 8

3、43-6:2004 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee RPI/13, Advanced technical ceramics. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the nece

4、ssary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations.BS EN 843-6:2009 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 843-6 August 2009 ICS 81.060.30 Supersedes CEN/TS 843-6:2004 Engli

5、sh Version Advanced technical ceramics - Mechanical properties of monolithic ceramics at room temperature - Part 6: Guidance for fractographic investigation Cramiques techniques avances - Proprits mcaniques des cramiques monolithiques temprature ambiante - Partie 6: Guide pour lanalyse fractographiq

6、ue Hochleistungskeramik - Mechanische Eigenschaften monolithischer Keramik bei Raumtemperatur - Teil 6: Leitlinie fr die fraktographische Untersuchung This European Standard was approved by CEN on 16 July 2009. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate

7、 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 exis

8、ts 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 b

9、odies 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.

10、EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR 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. EN 843-6:2009: EBS EN 843-6

11、:2009 EN 843-6:2009 (E) 2 Contents Page Foreword . 3 1 Scope 4 2 Normative references . 4 3 Terms and definitions . 4 3.1 General terms 4 3.2 Terms classifying inherently volume-distributed fracture origins 4 3.3 Terms classifying inherently surface-distributed fracture origins 5 3.4 Terms classifyi

12、ng features on fracture surfaces . 6 4 Significance and use 6 5 Apparatus 6 5.1 Preparation and cleaning facilities 6 5.2 Observational facilities . 7 6 Recommended procedure 9 6.1 Outline 9 6.2 Specimen storage and cleaning of fracture surfaces . 9 6.3 Visual inspection . 9 6.4 Optical microscope e

13、xamination . 10 6.5 Identification of major fracture surface features . 10 6.6 Scanning electron microscope examination . 12 6.7 Identification of fracture origin 12 6.8 Identification of chemical inhomogeneity at fracture origin 13 6.9 Drawing conclusions 13 7 Report . 13 Annex A (informative) Crac

14、k patterns in ceramic bodies . 14 Annex B (informative) Examples of general features of fracture surfaces 17 Annex C (informative) Examples of procedure for fracture origin identification. 19 C.1 Single large pores . 20 C.2 Agglomerates 22 C.3 Large grains . 24 C.4 Compositional inhomogeneities . 26

15、 C.5 Delaminations 28 C.6 Handling damage 30 C.7 Machining damage 31 C.8 Oxidation pitting 33 C.9 Complex origins 35 C.10 No obvious origins 36 Annex D (informative) Use of fracture mechanical information to aid fractography. 37 D.1 Fracture stress and origin size 37 D.2 Fracture stress and fracture

16、 mirror size . 40 Annex E (informative) Example layout of reporting pro-forma . 42 Bibliography . 44 BS EN 843-6:2009 EN 843-6:2009 (E) 3 Foreword This document (EN 843-6:2009) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI.

17、 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 February 2010, and conflicting national standards shall be withdrawn at the latest by February 2010. Attention is drawn to the possibility that som

18、e 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 843-6:2004. EN 843 Advanced technical ceramics Mechanical properties of monolithic ceramics at room

19、temperature consists of six parts: Part 1: Determination of flexural strength Part 2: Determination of Youngs modulus, shear modulus and Poissons ratio Part 3: Determination of subcritical crack growth parameters from constant stressing rate flexural strength tests Part 4: Vickers, Knoop and Rockwel

20、l superficial hardness Part 5: Statistical analysis Part 6: Guidance for fractographic investigation 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, C

21、zech 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. BS EN 843-6:2009 EN 843-6:2009 (E) 4 1 Sco

22、pe This Part of EN 843 contains guidelines to be adopted when evaluating the appearance of the fracture surface of an advanced technical ceramic. The purpose in undertaking this procedure can be various, for example, for material development or quality assessment, to identify normal or abnormal caus

23、es of failure, or as a design aid. NOTE Not all advanced technical ceramics are amenable to fractography. In particular, coarse-grained ceramics can show such rough surfaces that identifying the fracture origin may be impossible. Similarly, porous materials, especially those of a granular nature, te

24、nd not to fracture in a continuous manner, making analysis difficult. 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 d

25、ocument (including any amendments) applies. EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 General terms 3.1.1 crack disti

26、nct microstructural discontinuity arising during or after manufacture caused by the action of thermal and/or mechanical stress and leading to the generation of new surfaces which do not completely separate 3.1.2 flaw inhomogeneity which, through stress concentration, can act as a strength defining f

27、eature NOTE The term flaw used in this sense does not imply that the component is defective. 3.1.3 fracture process of propagation of a crack through a test-piece or component 3.1.4 fracture origin source from which failure commences 3.2 Terms classifying inherently volume-distributed fracture origi

28、ns 3.2.1 agglomerate unintentional microstructural inhomogeneity usually of altered density, for example a cluster of grains of abnormal size, particles, platelets or whiskers, resulting from non-uniformity in processing BS EN 843-6:2009 EN 843-6:2009 (E) 5 3.2.2 compositional inhomogeneity local va

29、riations in chemical composition, usually manifest as agglomerates (3.2.1), or as areas denuded of or enriched in dispersed phases, or as changes in grain size 3.2.3 delamination generally planar crack within a material arising from the method of manufacture 3.2.4 inclusion discrete inhomogeneity, u

30、sually as a result of inorganic contamination by a foreign body not removed during firing 3.2.5 large grain grain which is of abnormally large size as a result of poor particle size control or accelerated grain growth, and which can act as a flaw (3.1.2) 3.2.6 pore cavity or void within a material,

31、which may be isolated or continuously interconnected with others 3.2.7 porous region zone of enhanced porosity, usually three-dimensional in nature and resulting from inhomogeneity or organic contamination in processing 3.2.8 porous seam zone of enhanced porosity, usually linear or planar in nature

32、and resulting from inhomogeneity or organic contamination in processing 3.3 Terms classifying inherently surface-distributed fracture origins 3.3.1 chip small flake of material removed from a surface or an edge of an item or its fracture surface 3.3.2 handling damage scratches, chips or other damage

33、 resulting from contact between items, test-pieces or fracture surfaces, not present normally 3.3.3 machining damage result of removal of small chips (see 3.3.1) or the formation of scratches at, or cracks near, the surface resulting from abrasive removal of material 3.3.4 open pore void connected t

34、o the external surface, usually by virtue of machining 3.3.5 pit surface depression or surface connected shallow pore, usually resulting from manufacturing conditions or interaction with the external environment BS EN 843-6:2009 EN 843-6:2009 (E) 6 3.4 Terms classifying features on fracture surfaces

35、 3.4.1 fracture lines ridges or troughs running approximately parallel to the direction of propagation of a crack front, usually in the hackle (3.4.2) region NOTE In some cases, particularly with materials with low fracture toughness, additional lines can be found on fracture surfaces resulting from

36、 interactions of the crack with free surfaces or other features, including so- called Wallner lines, arrest lines, wake hackle, etc. Definitions of such terms can be found in ASTM C1256 (see reference 1 in the Bibliography). 3.4.2 hackle region of rough fracture outside the mirror (3.4.3) and mist (

37、3.4.4) regions, often with ridges or troughs emanating radially from the fracture origin (3.1.4) 3.4.3 mirror area of a fracture surface, usually approximately circular (or semicircular for near-edge fracture origins) and immediately surrounding a fracture origin (3.1.4), which is relatively flat an

38、d featureless compared with regions further removed from the fracture origin NOTE Not all materials or fractures show obvious fracture mirrors. They tend to be visible most clearly in high-stress, accelerating fractures from small flaws. 3.4.4 mist halo around the outer region of the mirror (3.4.3)

39、where the roughness is enhanced with a texture elongated in the direction of fracture NOTE The mist region is most clearly seen in glasses, glass-ceramics or ceramics with very fine grain sizes which produce smooth surfaces on fracture. 4 Significance and use Fractography is recommended as a routine

40、 diagnostic aid to the interpretation of fracture tests on test- pieces or of failures in components. Observation of the macroscopic features of fragments, such as cracks and their relative disposition, chips and scratches, provides information about the likely directions of stressing. Observation o

41、f intermediate scale features on the fracture surface, such as the shape of hackle (3.4.2) and fracture lines (3.4.1) give indications of the approximate position of the fracture origin (3.1.4). Microscopic observations give information on the nature of the fracture origin, and thus may provide evid

42、ence of the reasons for fracture. The accumulation of additional information about the conditions of fracture (stresses, forces, temperature, time under stress, likelihood of impact, etc.) is highly desirable for achieving justifiable conclusions. 5 Apparatus 5.1 Preparation and cleaning facilities

43、5.1.1 Cutting wheel, for large specimens. A diamond-bladed saw. NOTE This is needed to cut small samples for microscope observation, particularly in the scanning electron microscope BS EN 843-6:2009 EN 843-6:2009 (E) 7 5.1.2 Ultrasonic bath, for cleaning the fracture surface. 5.1.3 Compressed air su

44、pply, for drying specimens after cleaning and for removal of dust or lint. The supply should be dry and oil-free. 5.2 Observational facilities 5.2.1 Small hand lens, with a magnification in the range 3 to 8 times. 5.2.2 Optical microscope, preferably with photomicrographic facilities, and with varia

45、ble magnification in the range 5 to 50 times. NOTE As an alternative to photomicrographic facilities, a camera with appropriate lenses and a macrophotography stand. 5.2.3 Illumination system, a light source that can be positioned to the side of the test-piece to provide contrast on the fracture surf

46、ace. 5.2.4 Scanning electron microscope (SEM), preferably with energy-dispersive X-ray (EDX) analysis equipment fitted. BS EN 843-6:2009 EN 843-6:2009 (E) 8 Location of origin Collection and clean fragments History of fracture Objection Acton: Deduction: Result: Visual inspection Primary fracture fa

47、ce Binocular macroscope inspection Identify features and locate origin Tentative classification of origin More ? Mechanical nature of origin SEM inspection. Origin size, fracture mechanics Mechanical circumstances of fracture More ? Chemical nature of origin Report Overall conclusions Chemical cause

48、s of failure EDX analysis. Origin chemical inhomogeneity No No Yes YesFigure 1 Flow chart for general fractographic procedure BS EN 843-6:2009 EN 843-6:2009 (E) 9 6 Recommended procedure 6.1 Outline The sequence of steps in undertaking fractography on a specimen is outlined in Figure 1. It should be

49、 noted that not all the steps will be necessary on every occasion; for example, if only a check on approximate position of failure is needed, SEM examination is not generally necessary. Thus, the following series of paragraphs should be used as appropriate to the task, defined by the type of investigation needed. 6.2 Specimen storage and cleaning of fracture surfaces Fracture surfaces are rough and are prone to contamination in handling and storage. Contamination can lead to misinterpretation of observed features, especially in the SEM. Where poss