It is nowten yearssince the thirdeditionofMetallicMaterials, andovertwentysincethefirst edition. Overthis periodtheworkhasbeenextensivelyused as acomprehensivesourcebook by all those concerned with the use of engineering materials. Since the third edition, there have been a number of basic changes in the methods of specifyingmaterials. Probablythe mostimportantofwhich is the introductionofthe Unified Numbering System (UNS). These codes are issued in agreement between the Society of AutomotiveEngineers (SAE) and the American SocietyforTestingandMaterials(ASTM), and reflect the acknowledgement of a need for a numbering system with some logic. The UNS codes have been issued to cover all the trade names, codes and specifications used in the US, and cognizance has been takenofcodes used inother areas. The codes have a letter prefix - A for aluminium, C for copper, etc. - followed by a 5 figure code. This refers to a basic analysis and lists US specifications and trade names covered by this analysis.
This edition of Metallic Materials lists approximately 4,000 UNS codes and refers the reader either to the basic analysis for this code, or to one of the existing specifications or trade names covered by the code. In this edition steps have been taken to update the trade names and specifications, to eliminate mistakes, and to supply asmuchcontemporaryinformation as possible. Theextent ofthe additions has made it necessary to examine the way that someofthe specifications are known under various designations, and the implicationsofthis examination are explained in the 'How to use this book' section.