1、BRITISH STANDARD BS EN 23995:1993 ISO 3995:1985 Specification for Metallic powders Determination of green strength by transverse rupture of rectangular compacts The European Standard EN 23995:1993 has the status of a British Standard UDC 621.762:669-492.2:620.174BSEN23995:1993 This British Standard,
2、 having been prepared under the directionof the Iron and Steel Standards Policy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 15 June 1993 BSI 02-2000 The following BSI references relate to the work on this standard: Committee reference ISM/65 Special anno
3、uncement in BSINews January 1993 ISBN 0 580 21925 9 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 Oesterreichisches Normungsin
4、stitut Belgium Institut belge de normalisation Denmark Dansk Standardiseringsraad Finland Suomen Standardisoimisliito, r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normung e.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Icel
5、and Ireland National Standards Authority of Ireland Italy Ente Nazionale Italiano di Unificazione Luxembourg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Norm
6、alizacin y Certificacin Sweden Standardiseringskommissionen i Sverige Switzerland Association suisse de normalisation United Kingdom British Standards Institution Amendments issued since publication Amd. No. Date CommentsBSEN23995:1993 BSI 02-2000 i Contents Page Cooperating organizations Inside fro
7、nt cover National foreword ii Foreword 2 1 Scope and field of application 3 2 Principle 3 3 Apparatus 3 4 Sampling 3 5 Procedure 3 6 Expression of results 4 7 Test report 5 National annex NA (informative) Committees responsible Inside back cover Figure 1 Example of tooling to produce a rectangular t
8、est piece 5 Figure 2 Diagram of test fixture 6 Figure 3 Example of loading beam apparatus 6 Figure 4 Procedure of compacting and ejection 7BSEN23995:1993 ii BSI 02-2000 National foreword This British Standard has been prepared under the direction of the Iron and Steel Standards Policy Committee and
9、is the English language version of EN23995:1983 Metallic powders Determination of green strength by transverse rupture of rectangular compacts, published by the European Committee for Standardization (CEN). It is identical with ISO3995:1985, prepared by Technical Committee119, Powder metallurgy, of
10、the International Organization for Standardization (ISO) with the active participation of the UK. This British Standard supersedes BS5600-2.5:1988 which is withdrawn. This edition makes no technical changes to the standard. A British Standard does not purport to include all the necessary provisions
11、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, pagesi andii, the EN title page, pages
12、2to 8, 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.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 23995 April 1993 UDC 621.762:669-49
13、2.2:620.174 Descriptors: Powder metallurgy, metallic powder, compressed products, rectangular shape, mechanical tests, green strength, flexural strength English version Metallic powders Determination of green strength by transverse rupture of rectangular compacts (ISO 3995:1985) Poudres mtalliques D
14、termination de la rsistance de comprims rectangulaires cru (ISO3995:1985) Metallpulver Bestimmung der Prekrperfestigkeit von Probekrpern mit rechteckigem Querschnitt unter Biegebeanspruchung (ISO3995:1985) This European Standard was approved by CEN on 1993-04-02. CEN members are bound to comply with
15、 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 Secretaria
16、t 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 v
17、ersions. 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 Comit Europen de Normal
18、isation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1993 Copyright reserved to CEN members Ref. No. EN 23995:1993 EEN23995:1993 BSI 02-2000 2 Foreword In 1992, ISO3995:1985 Metallic powders Determination of green strength by transverse rupture of rectangul
19、ar compacts was submitted to the CEN Primary Questionnaire procedure. Following the positive result of the CEN/CS Proposal ISO3995:1985 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 pub
20、lication of an identical text or by endorsement, at the latest by October1993, and conflicting national standards shall be withdrawn at the latest by October1993. According to the Internal Regulations of CEN/CENELEC, the following countries are bound to implement this European Standard: Austria, Bel
21、gium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EN23995:1993 BSI 02-2000 3 1 Scope and field of application This International Standard specifies a method for the determination of green
22、 strength by measuring the transverse rupture strength of compacts of rectangular cross-section. 2 Principle Subjection of a compact pressed from metallic powder to a uniformly increasing transverse force under controlled conditions until fracture occurs. Determination of the transverse rupture stre
23、ngth, or green strength as used herein, as the stress, calculated from the flexure formula, required to break the compact as a simple beam supported near the ends and applying the force midway between the fixed centre of supports. The green strength is determined on compacts either having a particul
24、ar density or after compaction at a specific compacting pressure. 3 Apparatus 3.1 Die, preferably of cemented carbide or alternatively of tool steel, and two punches for producing rectangular test pieces with dimensions according to clause4. An example of a design for tooling is shown inFigure 1. 3.
25、2 Press, capable of applying forces up to about300kN with a minimum accuracy of 2% and adjustable to permit an even increase of the force at a rate no higher than50kN/s. 3.3 Balance, capable of weighing the compacts to an accuracy of 0,01g. 3.4 Micrometer or other suitable measuring device, for meas
26、uring the dimensions of the compacts to an accuracy of 0,01mm. 3.5 Fixture for testing, having two support cylinders (rollers) with a fixed distance between them and a load cylinder (roller). All three cylinders shall be3 0,1mm in diameter and shall be made of hardened steel with a hardness of at le
27、ast700HV, or of hardmetal. The cylinders shall be mounted parallel and the distance between the centres of the support cylinders shall be25 0,2mm, measured with an accuracy of 0,1mm. The load cylinders shall be mounted midway between the support cylinders. The mounting of the cylinders shall be such
28、 as to account for the permitted deviation from parallelism of the top and bottom faces of the test piece. A diagrammatic arrangement of a typical test fixture is shown inFigure 2. 3.6 Loading device, which may be either of the following: 3.6.1 A compression testing machine capable of determining th
29、e breaking force with a minimum accuracy of 2N. 3.6.2 A loading beam apparatus to properly locate the test piece and which is capable of applying a breaking force through a lever arrangement. The applied force can be exerted by various systems, an example of which is given inFigure 3. The applied fo
30、rce on the test piece shall be calculated to an accuracy of 2N. 4 Sampling The quantity of the test sample shall be chosen to give three test pieces with the dimensions10to13mm wide, at least30mm long and5,5to6,5mm thick. The thickness of the test piece shall be uniform within0,1mm over the distance
31、 between supports. If necessary, preliminary tests should be made in order to establish the quantity of powder which is needed to fulfil this requirement. 5 Procedure 5.1 Cleaning of the die and punches Wipe the die cavity and the punches with soft and clean paper towelling soaked with an appropriat
32、e solvent such as acetone. Allow the solvent to evaporate. 5.2 Powder testing conditions 5.2.1 Powders which do not contain a lubricant can be compacted in the following ways: a) in a dry die (WARNING: seizure and excessive die wear may occur, particularly at high compacting pressures); b) in a die
33、with lubricated walls (see5.3.1); c) after admixing a lubricant (see5.3.2) and in a dry die. 5.2.2 Powders which contain a lubricant can be compacted in the following ways: a) in a dry die; b) after admixing additional lubricant (see5.3.2) and in a dry die.EN23995:1993 4 BSI 02-2000 5.3 Lubrication
34、Use one of the following methods of lubrication. 5.3.1 Die wall lubrication Apply to the die walls a mixture or a solution of a lubricant in a volatile liquid, for example100g of zinc stearate in1000cm 3of acetone. After any excess liquid has drained away, allow the solution adhering to the walls to
35、 evaporate leaving a thin layer of lubricant. 5.3.2 Lubrication of powder Lubricate the powder to be tested by thoroughly mixing into it a quantity (for example0,5to1,5%) of a suitable solid lubricant (for example zinc stereate or stearic acid). 5.4 Compacting and ejection Insert the lower punch int
36、o the die cavity. Position the die to the desired filling height by using supporting spacers between the die and the foot of the lower punch. Pour the sample into the die cavity, taking the usual precautions to ensure that the powder is uniformly distributed in the die cavity. Position the upper pun
37、ch and place the die with the punches between the platens of the press. Apply and release a preliminary force of approximately20kN. Remove the spacers supporting the die. If the die is supported by springs, or in some similar way, it is not necessary to apply the preliminary force. Apply the final f
38、orce at a constant rate which shall not exceed50kN/s. Eject the compact from the die by means of the lower punch. The procedure of compacting and ejection is exemplified inFigure 4. 5.5 Compacting pressure Green strength can be determined at a given pressure or density following agreement between su
39、pplier and customer. In the first case the recommended pressure is400N/mm 2 . In the second case, when test pieces are pressed to a given density, the maximum deviation between the three test pieces shall not exceed0,1g/cm 3 . 5.6 Determination of density Measure the length, width and thickness of t
40、he test piece in the plane of application of the force to the nearest0,01mm. Determine the mass and the volume (calculated from the average value of dimensions). 5.7 Determination of breaking force Break the test piece under controlled conditions using either a compression testing machine or a loadi
41、ng beam device. 5.7.1 Method 1 Using a compression testing machine Position the test piece in the transverse rupture test fixture (seeFigure 2) so that it is centrally located and perpendicular to the axis of the support cylinders. Place the fixture between the platens of the testing machine and app
42、ly a compressive force at a unifrom rate such that the test piece fractures within a time not less than10s. Record the breaking force to the nearest2N. 5.7.2 Method 2 Using a loading beam device (seeFigure 3) Adjust the balance of the beam so that it is level. Position the test piece in the loading
43、beam device so that it is centrally located and perpendicular to the axis of the support cylinders. Increase the load at a uniform rate such that the test piece fractures within a time not less than10s. Determine the input force to the nearest2N. NOTEWhen a container and shot are used, the beam shal
44、l be balanced with the container in position. The load exerted is then calculated from the mass of the shot only. 6 Expression of results 6.1 Calculate the density of the test piece from its mass and volume. Calculate the artithmetical mean of the determination on three different test pieces to the
45、nearest0,05g/cm 3 . 6.2 The green strength S, expressed in newtons per square millimetre, is given by the formula where 6.3 Calculate the arithmetical mean of the three determinations rounded to the nearest0,2N/mm 2for values up to and including10N/mm 2and to the nearest0,5N/mm 2for values greater t
46、han10N/mm 2 . P is the force, in newtons, required to rupture; L is the length, in millimetres, of span of the fixture; t is the thickness, in millimetres, of the test piece; w is the width, in millimetres, of the test piece.EN23995:1993 BSI 02-2000 5 7 Test report The test report shall include the
47、following information: a) reference to this International Standard; b) all details necessary for identification of the test sample; c) the type, nature and amount of the lubricant, if it has been added to the powder; in certain cases it may be desirable to report how the lubricant was added; d) the
48、density of the test pieces or the compacting pressure; e) compacting die material (tool steel or cemented carbide); f) the result obtained; g) all operations not specified by this International Standard, or regarded as optional; h) details of any occurrence which may have affected the result. NOTEMa
49、ting parts shall be fitted and lapped. Figure 1 Example of tooling to produce a rectangular test pieceEN23995:1993 6 BSI 02-2000 Figure 2 Diagram of test fixture Figure 3 Example of loading beam apparatusEN23995:1993 BSI 02-2000 7 Figure 4 Procedure of compacting and ejection8 blankBSEN23995:1993 BSI 02-2000 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/-) t
