BS EN ISO 03928-2016

BS EN ISO 3928:2016 Sintered metal materials, excluding hardmetals — Fatigue test pieces (ISO 3928:1999) BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN ISO 3928:2016 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN ISO 3928:2016. It is identical to ISO 3928:1999. It supersedes BS EN ISO 3928:2006 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee ISE/65, Sintered metal components. 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 necessary provisions of a contract. Users are responsible for its correct application. © The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 91033 3 ICS 77.040.10; 77.160 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2016. Amendments issued since publication Date Text affected EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN ISO 3928 July 2016 ICS 77.160; 77.040.10 Supersedes EN ISO 3928:2006 English Version Sintered metal materials, excluding hardmetals - Fatigue test pieces (ISO 3928:1999) Matériaux métalliques frittés, à l exclusion des métaux- durs - Éprouvettes pour essais de fatigue (ISO 3928:1999) Sintermetallwerkstoffe, ausgenommen Hartmetalle - Probekörper für die Ermüdungsprüfung (ISO 3928:1999) This European Standard was approved by CEN on 29 June 2016. 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-CENELEC 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-CENELEC 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 3928:2016 EBS EN ISO 3928:2016 EN ISO 3928:2016 (E) 3 European foreword The text of ISO 3928:1999 has been prepared by Technical Committee ISO/TC 119 “Powder metallurgy” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 3928:2016. 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 January 2017, and conflicting national standards shall be withdrawn at the latest by January 2017. 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 EN ISO 3928:2006. 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 3928:1999 has been approved by CEN as EN ISO 3928:2016 without any modification. BS EN ISO 3928:2016 INTERNATIONAL STANDARD © ISO ISO 3928:1999(E) 1 Sintered metal materials, excluding hardmetals — Fatigue test pieces 1 Scope This International Standard specifies: the die cavity dimensions used for making fatigue test pieces by pressing and sintering, together with certain dimensions of the test piece obtained from such a die; the dimensions of the test pieces machined from sintered and powder forged materials. This International Standard is applicable to all sintered metals and alloys, excluding hardmetals. 2 Pressed and sintered test pieces for fatigue test by reverse bend and axial testing 2.1 General The pressed and sintered piece may also be subjected to further treatment, such as sizing, polishing or heat treatment. If such treatments are applied, they shall be stated in the test report. In a metallographically examined cross section of a test piece, in the gauge region, the piece shall show no micro-lamination greater than 0,25 mm in length. Corners shall be broken in the gauge area. 2.2 Test piece specification: unnotched Figure 1 a) shows a drawing of the unnotched test piece. The flatness and parallelism of 0,1 mm are mandatory. The other dimensions are advisory. Burrs shall be avoided. 2.3 Test piece specification: notched Figure 2 a) shows a drawing of the notched test piece. The flatness and parallelism of 0,1 mm are mandatory. The other dimensions are advisory. Burrs shall be avoided. The tooling radius 5,5 mm of the die is subject to wear, then the corresponding radius dimension of the test piece shall be reported. 3 Die specifications 3.1 General The die should preferably be of hardmetal and its surface finish shall be such as to allow compression of test pieces under normal conditions. The die may include a small exit taper to facilitate ejection and avoid cracks or microlaminations in the test pieces. Die cavity may be tapered 0,01 per side to aid ejection. Die bore may be enlarged by 0,5 % for tooling to be used for repressing. The die should be well supported with shrink rings (of internal diameter 0 001 + , 120mmmm), so as to minimize lateral expansion during compacting. Such support decreases the possibility of cracking of the specimen at ejection. To reduce the incidence of cracks in the specimen, it is recommended to use top punch hold down during ejection.BS EN ISO 3928:2016 ISO 3928:1999(E) © ISO 2 3.2 Die specifications for unnotched test pieces The recommended die cavity is shown in Figure 1 b). 3.3 Die specifications for notched test pieces The recommended die cavities are shown in Figure 2 b). 4 Machined test pieces Many types of machined test piece may be used according to the different known procedures of fatigue testing (rotating beam, axial loading, reverse bending, etc.) except that it is not recommended to machine test pieces with square or rectangular cross sections. An example of the rotating beam piece, is given in Figure 3. Figure 4 shows an example of a test piece for axial loading fatigue testing. The machined test pieces shall be ground over their active length, using a diamond wheel, and lapped longitudinally in order to remove all traces of circumferential scratches. Final polishing should be in the longitudinal direction (no circumferential scratch lines should be visible); try to achieve a smooth blend with no undercut. Cold work and stresses from machining significantly increase the yield strength of austenitic stainless steel. Annealing or stress relieving may be required to duplicate the as-sintered structure. Any such heat treatment shall be reported. Practical experience with fatigue testing of carefully machined test pieces of circular cross section has shown that their endurance limits may be 20 % to 30 % higher than those obtained on unmachined, as-moulded test pieces with square or rectangular cross sections. Use progressively lighter machining passes to minimize residual stresses. Diameter in gauge length should be uniform within – 0,025 mm. 5 Identification of test pieces For the identification of test pieces, the following shall be stated: a) reference to this International Standard, i.e. ISO 3928; b) type of material; c) density of test piece; d) dimensions of test piece (thickness); e) when pressed and sintered test pieces are made according to clause 2, the nature of any finishing treatment shall be stated and also, preferably, the material and surface finish of the compacting tool; f) form of test piece, i.e. figure number; g) die material, i.e. tool steel or hardmetal/carbide; h) whether as-sintered or heat treated; i) hardness of test piece according to heat treatment; j) bottom of notch radius used on notched test piece, Figure 2.BS EN ISO 3928:2016 © ISO ISO 3928:1999(E) 3 Dimensions in millimetres k a) Test piece b) Die Figure 1 — Unnotched test piece and compacting die for use with unnotched fatigue test piecesBS EN ISO 3928:2016 ISO 3928:1999(E) © ISO 4 Dimensions in millimetress a) Test piece b) Die The stress concentration factor K tdepends upon radius R, as follows: rK t axial loading K t reverse bending 0,9 – 0,02 2,41,8 0,45 – 0,02 3,22,4 Figure 2 — Notched test piece and compacting die for use with notched fatigue test piecesBS EN ISO 3928:2016 © ISO ISO 3928:1999(E) 5 Dimensions in millimetress Figure 3 — Machined rotating beam fatigue test piece Figure 4 — Machined axial loading test pieceBS EN ISO 3928:2016 ISO 3928:1999(E) © ISO 6 Annex A (informative) Remarks ISO 1099, ISO 1352 and ISO 1143 define the general principles of fatigue testing of metals. These principles are applicable to sintered metals with the following remarks. a) Sintered metals are characterized by the presence of pores, which are unavoidable stress raisers. b) Porosity reduces the actual cross section of the specimen to be tested; this means that the nominal stress values, as calculated from the usual formulae, are smaller than the true stresses. c) In most cases, the presence of interconnected pores opening to the surface makes sintered pieces much more sensitive to environmental conditions than pore-free materials are; porous products can be affected by internal corrosion processes not only during fatigue testing, but also before the test therefore such test pieces must be stored more carefully than pore-free test pieces. d) The surface state of a test specimen or PM part significantly influences its fatigue behaviour; therefore, in order to obtain a proper transmission of fatigue data obtained with specimens used to assess the fatigue behaviour of PM component, the surface states of specimens and components must be comparable. e) Machining by milling or turning densifies the surface and introduces compressive residual stresses. This leads to a much higher fatigue strength compared to the non-machined state. (A grinding operation is much softer.) Therefore, surface machining of test specimens should be carried out only in cases where the critical area of a PM part is also machined. However, as most PM parts have non-machined surfaces, evaluation of the fatigue behaviour should preferably be performed by transmission of fatigue data obtained with non-machined surfaces.BS EN ISO 3928:2016 © ISO ISO 3928:1999(E) 7 Bibliography [1] ISO 296, Machine tools — Self-holding tapers for tool shanks. [2] ISO 1099, Metals — Axial fatigue testing. [3] ISO 1143, Metals — Rotating bar bending fatigue testing. [4] ISO 1352, Steel — Torsional stress fatigue testing.This page deliberately left blankThis page deliberately left blankBSI is the national body responsible for preparing British Standards and other standards-related publications, information and services. BSI is incorporated by Royal Charter. 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