ISO INTERNATIONAL STANDARD 683-15 Second edition 1992-08-15 Heat-treatable steels, alloy steels and free-cutting steels Part 15: Valve steels for internal combustion engines Aciers pour traitement thermique, aciers allies et aciers pour decolletage Partie 15: Aciers pour soupapes de moteurs a combustion interne Reference number ISO 683-15:1992(E) ISO 683-15:1992(E) Foreword sO (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 matters of electrotechnical standardization Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Inter- bodies casting avote. International Standard isO 683-15 was prepared by Technical Committee ISO/TC 17, Steel, Sub-Committee SC 4, Heat treatable and alloy steels. This second edition cancels and replaces the first edition (Iso 683-15:1976), of which it constitutes a technical revision. Iso 683 consists of the foliowing parts, under the general title Heat. treatable steels, alloy steels and free-cutting steels: Part 1: Direct-hardening unalloyed and tow-alloyed wrought steel in form of different black products - Part g: Wrought free-cutting steels 一 Part 10: Wrought nitriding steels -- Part 11: Wrought case-hardening steels - Part 13: Wrought stainless steels Part 15: Valve steels for internal combustion engines Part 16: Precipitation hardening stainless steels Part 17: Ball and roller bearing steels ISO1992 or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56· CH-1211 Geneve 20 · Switzerland Printed in Switzerland ii ISO 683-15:1992(E) Part 18: Bright products of unalloyed and low alloy steels Annex A of this part of Iso 683 is for information only ii