BRITISH STANDARD Specification for Hardmetals — Metallographic determination of microstructure The European Standard EN 24499:1993 has the status of a British Standard UDC 669.018.25:620.186 BS EN 24499:1993 ISO 4499:1978 BS EN 24499:1993 Cooperating organizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Belgium Denmark Finland France Germany Greece Iceland Ireland Italy Luxembourg Netherlands Norway Portugal Spain Sweden Switzerland United Kingdom This British Standard, having been prepared under the direction of the Iron and Steel Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 June 1993 © BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference ISM/65 Special announcement BSI News January 1993 ISBN 580 21922 Oesterreichisches Normungsinstitut Institut belge de normalisation Dansk Standardiseringsraad Suomen Standardisoimisliito, r.y Association franỗaise de normalisation Deutsches Institut fỹr Normung e.V Hellenic Organization for Standardization Technological Institute of Iceland National Standards Authority of Ireland Ente Nazionale Italiano di Unificazione Inspection du Travail et des Mines Nederlands Normalisatie-instituut Norges Standardiseringsforbund Instituto Portuguès da Qualidade Asociación Espola de Normalización y Certificación Standardiseringskommissionen i Sverige Association suisse de normalisation British Standards Institution Amendments issued since publication Amd No Date Comments BS EN 24499:1993 Contents Cooperating organizations National foreword Foreword Scope and field of application Symbols and designations Apparatus Preparation of test piece section Procedure Test report National annex NA (informative) Committees responsible Figure ắ-phase ì 500 Figure — !-phase × 500 Table Table © BSI 12-1999 Page Inside front cover ii 3 3 3 Inside back cover i BS EN 24499:1993 National foreword This British Standard has been prepared under the direction of the Iron and Steel Standards Policy Committee and is the English language version of EN 24499:1993 Hardmetals — Metallographic determination of microstructure, published by the European Committee for Standardization (CEN) It is identical with ISO 4499:1978, prepared by Technical Committee 119 “Powder metallurgy”, of the International Organization for Standardization (ISO) with the active participation of the UK This British Standard supersedes BS 5600-4.13:1980, which is withdrawn This edition makes no technical changes to the standard A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application Compliance with a British Standard does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages to 6, an inside back cover and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover ii © BSI 12-1999 EUROPEAN STANDARD EN 24499 NORME EUROPÉENNE April 1993 EUROPÄISCHE NORM UDC 669.018.25:620.186 Descriptors: Powder metallurgy, hard metals, metallography, microscopic analysis, microstructure, grain structure English version Hardmetals — Metallographic determination of microstructure (ISO 4499:1978) Métaux-durs — Détermination métallographique de la microstructure (ISO 4499:1978) Hartmetalle — Metallographische Bestimmung der Mikrostruktur (ISO 4499:1978) This European Standard was approved by CEN on 1993-04-02 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 Central Secretariat 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 Central Secretariat has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1993 Copyright reserved to CEN members Ref No EN 24499:1993 E EN 24499:1993 Foreword In 1992, ISO 4499:1978 Hardmetals — Metallographic determination of microstructure was submitted to the CEN Primary Questionnaire procedure Following the positive result of the CEN/CS Proposal ISO 4499:1978 was submitted to the Formal Vote The result of the Formal Vote was positive 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 October 1993, and conflicting national standards shall be withdrawn at the latest by October 1993 According to the Internal Regulations of CEN/CENELEC, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom © BSI 12-1999 EN 24499:1993 Scope and field of application This International Standard specifies methods of metallographic determination of the microstructure of hardmetals Symbols and designations Table Symbol Designation µ-phase Tungsten carbide ¶-phase Binder phase (for example based on Co, Ni, Fe) ¾-phase Carbide having a cubic lattice (for example TiC, TaC) which may contain other carbides (for example WC) in solid solution ½-type phases Multiple carbides of tungsten and at least one metal of the binder phase Apparatus 3.1 Metallographic microscope, permitting observations at magnifications up to 500 × 3.2 Equipment for preparation of test-piece sections Preparation of test-piece section The test-piece section shall be prepared as for metallographic examination and the surface to be examined shall be free from grinding and polishing marks Care shall be taken to avoid tearing out of particles, which may lead to a wrong evaluation of microstructure NOTE There are several methods for preparation of hardmetal surfaces for metallographic examination Firstly, careful coarse grinding is carried out to remove sufficient material to ensure that the true structure is revealed After grinding with fine diamond grit wheels, polishing is effected by using diamond paste or diamond powders of progressively finer grain size down to 4m on rigidly supported laps of, for example, thin plastic, thin felt or paper Procedure The microstructure is examined by the gradual development of phases by etching There are several methods for etching hardmetal surfaces for metallographic examination Examples of suitable etching techniques are given in Table Care shall be taken to ensure that the true microstructure is revealed © BSI 12-1999 5.1 The existence of ½-type phases is determined after lightly etching the section, for example by technique (see Table 2) Phases of ½-type are coloured orange to brown, while other phases are unetched Etching by technique does not prevent subsequent etching by techniques and The whole surface is examined at a low magnification and, if necessary, at magnifications up to 500 × The existence and distribution of ½-type phases is noted and recorded 5.2 The existence of ¾-type phases is determined after etching the surface, for example by technique (see Table 2) This phase is coloured light yellowish-brown and has a typically rounded shape (see Figure 1) The etched section is examined and the existence of ¾-phase is noted and recorded Its size is estimated and recorded according to Figure as ¾-fine, ¾-medium or ¾-coarse 5.3 The existence of µ-phase is determined after etching the surface, for example by technique or, in the case of the presence of ¾-phase, by technique (see Table 2) The µ-phase appears grey and often has an angular shape The etched section is examined and the existence of µ-phase is noted and recorded Its size is estimated and recorded according to Figure as µ-fine, µ-medium or µ-coarse 5.4 The ¶-phase is identified after etching the surface, for example by technique or (see Table 2) This phase remains white Test report The test report shall include the following information: a) reference to this International Standard; b) all details necessary for identification of the test sample; c) the result obtained; d) all operations not specified by this International Standard, or regarded as optional; e) details of any occurrence which may have affected the result EN 24499:1993 Table Etching technique Composition of etchants Conditions of etching Application of etching A Freshly prepared mixture of equal quantities of 10 to 20 % (m/m) aqueous solutions of potassium hexacyanoferrate(III) (potassium ferricyanide) and potassium or sodium hydroxide Etch in mixture A at approximately 20 °C Identification for to 20 s Flush the test-piece section of ½-phases with water immediately, without removing the oxide layer Dry the surface carefully with acetone or alcohol without wiping A See technique Etch at approximately 20 °C in mixture A Identification of ¾-phase for to Then wash in water and etch in mixture B for approximately 10 s Next wash in water, then in alcohol, and dry the test-piece section Finally, etch in mixture A for approximately 20 s B A mixture of equal volumes of concentrated hydrochloric acid and water A See technique Etch in mixture A at approximately 20 °C Identification for to of µ-phase NOTE The separate solutions of potassium hexacyanoferrate(III) and potassium or sodium hydroxide may be stored for a long time, but must be freshly mixed each day when used © BSI 12-1999 EN 24499:1993 Figure ắ-phase ì 500 â BSI 12-1999 EN 24499:1993 Figure à-phase ì 500 © BSI 12-1999 BS EN 24499:1993 National annex NA (informative) Committees responsible The United Kingdom participation in the preparation of this European Standard was entrusted by the Iron and Steel Standards Policy Committee (ISM/-) to Technical Committee ISM/65 upon which the following bodies were represented: British Hardmetal Association Federation of British Engineers (Test Manufacturers) Society of Motor Manufacturers and Traders Limited Coopted member © BSI 12-1999 BS EN 24499:1993 ISO 4499:1978 BSI — British Standards 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