ISO INTERNATIONAL STANDARD 2624 Second edition 1990-02-01 Copper and copper alloys - Estimation of average grain size Cuivre et alliages de cuivre -- Evaluation de la dimension moyenne du grain Referencenumber ISO 2624 : 1990 (E) Not for Resale ISO 2624 :1990 (E) Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (isO member bodies). The work of preparing International Standards is normally carried out through iso technical committees. Each member body interested in a subject for which a technical committee has been established has 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 mattersof 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 ISO 2624 was prepared by Technical Committee ISO/TC 26, Copperand copperalloys. This second edition canceis and replaces the first edition (1S0 2624 : 1973), of which it constitutes aminorrevision. Annex A forms an integral part of this International Standard. ?ISO 1990 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International OrganizationforStandardization Case postale 56 . CH-1211 Geneve 20 . Switzerland Printed in Switzerland Notfor Resale ISO2624 : 1990 (E) Introduction On a section of metal, a grain is that area within the boundary of a crystal. For the pur- pose of applying the methods described in this international Standard, a crystal and its twin bands are considered as one grain. Sub-grains, minor constituent phases, in- clusions and additives are not considered in the estimation of the grain size. Itis important, in using these methods,torecognize that the estimation ofgrain size is not a precise measurement. A metal structure is an aggregate of three-dimensional crystals of varying sizes and shapes. Even if all these crystals were identical in size and shape, the grain cross-sections produced by a random plane (surface of observation) through such a structure would have a distribution of areas varying from a maximum value to zero, depending upon where the plane cuts each individual crystal. Clearly, no twofieldsof observation canbeexactlythe same. Practical reasons limit the number of grains that can reasonably be counted to less than the number statistically desirable. ili CopyrightInenationaOrganizationfrStandardizati No reproduction or networking permited without license from IHS Not for Resale