Unified Numbering System for Nonferrous Metals and Alloys

The Unified Numbering System (UNS), is a designation system is formed by American Society for Testing Materials (ASTM) E52 and Society of Automotive Engineers (SAE) J1086 to correlate systems that are adopted by Aluminum Association (AA), ASTM, individuals and others users.

The UNS designation assignments for metals and alloys are established by ASTM or other appropriate trade associations. Each assigner administers a specific UNS designation series, considers the request for assignment of new designations to be included into the system and notifies the action taken towards the assignments to the applicants. The assigners also reports the details of new assignments to the office for the Unified Numbering System for Metals and Alloys immediately

This designation system has 9 sets of designations for nonferrous metals and alloys. Each designation comprises five digit numbers preceded by a single- letter prefix. The letter in the designation indicates the identified metal family in many cases: for instance, A - Aluminum and Aluminum alloys, C - Copper and Copper Alloys, N - Nickel and Nickel alloys, etc.

The UNS number does not require quality, condition, form, etc and hence it is not merely a specification. The UNS number rather serves as a distinct identification of metals and alloys, which have formerly established control limits.

The correlation provided by UNS avoids the confusion resulting from having same identification number for two or more materials and by the usage of more than one number for the same material. In addition, the UNS provides the uniformity required for purposes of cross referencing, storage and retrieval of data, maintaining record and efficient indexing.

Table 1. UNS Designations (or Codes) Established for Nonferrous Metals and Alloys