ISO INTERNATIONAL STANDARD 3738-2 First edition 1988-12-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEKAYHAPOAHAA OPIAHM3AUMA NO CTAHAAPTW3ALMM Hardmetals-Rockwellhardnesstest(scaleA)- Part 2 : Preparation and calibration of standard test blocks Metauxdurs -Essai dedureteRockwell (echelleA)- Partie2:Preparation et étalonnage desblocs de reference Reference number ISO 3738-2: 1988 (E) ISO 3738-2 :1988 (E) Foreword ISo (the International Organization for Standardization) is a woridwide federation of national standards bodies (ISo member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member bodyinterested inasubjectforwhichatechnicalcommitteehasbeenestablishedhas the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISo Council. They are approved in accordance with iSO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO3738-2was preparedbyTechnicat CommitteeISO/TC119, Powder metallurgy. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. @International OrganizationforStandardization,1988 Printed in Switzerland INTERNATIONALSTANDARD ISO3738-2:1988(E) Hardmetals - Rockwell hardness test (scale A) Part 2 : Preparation and calibration of standard test blocks 1 Scope and field of application than a total of 1 % (m/m) of other carbides (e.g. of titanium tantalum, niobium). The composition and structure shall be This part of ISO 3738 specifies the preparation and calibration chosen to give the desired hardness. Free carbon and eta- of hardmetal primary standard test blocks, secondary standard phase shall be absent. test blocks and working standard test blocks from master stan- dard test blocks to be used for the verification of Rockwell 4.2 Standard test blocks shall have a nominal diameter of hardness testing machines (scale A) and indenters for testing 45 mm and a nominal thickness of 8 mm. The bottom face shall hardmetals. be chamfered 0,8 mm by 45°. This document should be read in conjunction with iSO 3738-1. 4.3 Every standard test block shall be ground on both flat faces. The face on which indentations are to be made shall have a surface finish of Ra < 0,2 μm, and may be polished. 2 Reference The maximum deviation in flatness of the surfaces shall not ISo3738-1,Hardmetals-Rockwellhardnesstest(scaleA)-- exceed 0,o10 mm.The bottom of the blocks shall not be Part1:Testmethod. convex. Themaximum deviation in parallellism shall not exceed 3 Symbols anddesignations 0,020 mm per 50 mm. Table 1 5 Master standard test blocks Symbo! Designation 51 Standard deviation of hardness determinations on 5.1 Two sets of fivemaster standard test blocks each shall be the first surface of a primary standard test block retained by the Cemented Carbide Producers Association (CCPA), USA, and one set shall be retained by the Secretariat $2 Standard deviation of hardness determinations on the test surface of a primary standard test block ofISO/TC119. Sp Mean standard deviation of hardness determi- One of the sets retained in the USA shall be used for calibrating nations on a primary standard test block. primary standard test blocks. Standard deviations shall be calculated using the equation 5.2 The markings and internationally agreed hardnesses and standard deviations of three sets of the five master test blocks are given in tab