ISO 6157-1 INTERNATIONAL STANDARD First edition 1988-08-01 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION Fasteners - Surface discontinuities -- Part 1 : Bolts, screws and studs for general requirements Elementsdefixation-Defautsdesurface- Partie 1: Boulons, vis et goujons d'usage general Reference number ISO 6157-1 : 1988 (E) Not for Resale 1SO 6157-1 : 1988 (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 normaly 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 approval before their acceptance as International Standards by the ISso Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 6157-1 was prepared by Technical Committee ISO/TC 2, Fasteners. 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 Organization for Standardization, 1988 Printed in Switzerland mitted without license from IHS Not for Resale ISO 6157-1 : 1988 (E) INTERNATIONAL STANDARD Fasteners - Surface discontinuities - Part 1 : Bolts, screws and studs for general requirements 1 Scope and field of application NOTES 1 The figures in clause 3 are examples only. They apply correspond- ingly also to other types of bolts, screws and studs. 1.1 This part of ISO 6157 establishes limits for various types of surface discontinuities on bolts, screws and studs for general 2 The individual figures show the surface discontinuities exaggerated in some cases for clarity. requirements. It applies to bolts, screws and studs with 2 References nominal thread diameters 5 mm and larger; Iso 468, Surface roughness - Parameters, their values and general rules for specifying requirements. product grades A and B; Iso 898-1, Mechanical properties of fasteners -- Part 1: Bolts, property classes up to and including 10.9, unless other- screws and studs. wise specified in product standards or agreed between Iso 2859, Sampling procedures and tables for inspection by supplier and purchaser. attributes. Iso 3269, Fasteners -- Acceptance inspection. 1.2 Limits for surface discontinuities on bolts, screws and studs for special requirements (e.g. automatic assembly) are laid down in IS0 6157-3. When the engineering requirements 3 Types, causes, appearance and limits of the application necessitate that surface discontinuities on of surface discontinuities bolts, screws and studs be more closely controlled, it should be specified in the respective product standard, or the purchaser shall specify the applicable limits in the inquiry and purchase 3.1 Cracks order. A crack is a clean (crystalline) fracture passing through or across the grain boundaries and may possibly follow inclusions 1.3 Where the permissible limits for surface discontinuities of foreign elements. Cracks are normally caused by overstress- indicated in clause 3 occur, the minimum values for the ing the metal during forging or other forming operations, or mechanical and functional properties specified in 1so 898-1 during heat treatment. Where parts are subjected to significant should stil! be met. reheating, cracks usually are discoloured by scale. 1 Copyright International Organization fo