Introduction to the Unified Numbering System of Nonferrous Metals and Alloys
Abstract
The Unified Numbering System (UNS) is a standardized designation system established under ASTM E527 and SAE J1086 for numbering metals and alloys. This system provides a unified method for correlating various numbering systems used by organizations such as the American Society for Testing Materials (ASTM) and the Aluminum Association (AA). The UNS establishes nine series of designations for nonferrous metals and alloys, with each designation consisting of a single-letter prefix followed by five digits. The letter prefix typically represents the metal family, such as A for aluminum, C for copper alloys, and Z for zinc alloys. This system eliminates confusion caused by multiple identification numbers for the same material while ensuring uniformity in indexing, record keeping, and cross-referencing across the metals industry.
Understanding the Unified Numbering System Framework
The Unified Numbering System represents a comprehensive approach to metal and alloy identification that addresses the complexity of multiple numbering systems used throughout the industry. Established in accordance with ASTM E527 and SAE J1086 Recommended Practice for Numbering Metals and Alloys, this system serves as a bridge between various organizational standards and individual user requirements.
The primary purpose of the UNS extends beyond simple identification. It provides a standardized means of correlating systems used by major organizations including the American Society for Testing Materials (ASTM) and the Aluminum Association (AA), while also accommodating the needs of individual users and producers. This comprehensive approach ensures that all stakeholders in the metals industry can communicate effectively using a common identification language.
UNS Designation Structure and Metal Classification
The UNS designation system establishes nine distinct series of designations specifically for nonferrous metals and alloys. Each UNS designation follows a consistent format consisting of a single-letter prefix followed by five digits. This structure provides both clarity and systematic organization that facilitates easy identification and categorization.
The letter prefix system demonstrates intuitive design, with letters typically suggestive of the metal family they represent. For example, the letter A designates aluminum and aluminum alloys, C represents copper and copper alloys, and Z identifies zinc and zinc alloys. This logical approach makes the system user-friendly while maintaining technical precision.
Administration and Assignment Process
UNS designation assignments undergo processing through ASTM or other relevant trade associations, with each assignor bearing responsibility for administering specific UNS series designations. This distributed approach ensures that subject matter experts oversee their respective metal categories while maintaining system-wide consistency.
The assignment process involves careful consideration of requests for new UNS designations, with assignors evaluating each application and informing applicants of the action taken. Once approved, UNS designation assignors report immediately to the office of the Unified Numbering System for Metals and Alloys, providing details of each new assignment for inclusion into the comprehensive system database.
System Benefits and Industry Impact
The UNS provides substantial benefits to the metals industry by correlating many internationally used numbering systems currently administered by societies, trade associations, and individual users and producers. This correlation eliminates the confusion that arises from using multiple identification numbers for the same material, while also preventing the problematic situation where identical numbers are assigned to entirely different materials.
The system delivers the uniformity necessary for efficient indexing, record keeping, data storage and retrieval, and cross-referencing operations. This standardization proves particularly valuable in today's globalized metals industry, where materials may be specified, produced, and used across multiple countries and organizations.
Important System Limitations and Clarifications
It is crucial to understand that the UNS number functions as an identification tool rather than a specification document. The UNS designation establishes no requirements for form, condition, quality, or other material properties. Instead, it serves as a unified identification system for metals and alloys that have controlling limits established in specifications published by other organizations.
This distinction ensures that the UNS maintains its role as a correlation and identification system while allowing established standards organizations to maintain their authority over material specifications and requirements. Users must reference appropriate specifications from ASTM, AA, or other relevant organizations to obtain complete material requirements.
Table 1. Description of Numbers (or Codes) Established for Nonferrous Metals and Alloys
| Designation | Description |
| A00001-A99999 | Aluminum and aluminum alloys |
| A01001-A63562 | Aluminum Foundry Alloys, Ingot or Casting |
| A82014-A87475 | Wrought Aluminum Alloys Clad with Wrought Aluminum Alloys, Non- or Heat Treatable |
| A91030- A91450 | Wrought Aluminum Alloys, Non- Heat Treatable |
| A93002-A95954 | Wrought Aluminum Alloys, Non- Heat Treatable |
| A98001-A98280 | Wrought Aluminum Alloys, Non- Heat Treatable |
| A92001-A92618 | Wrought Aluminum Alloys, Heat Treatable |
| A96002-A97472 | Wrought Aluminum Alloys, Heat Treatable |
| C00001-C99999 | Copper and copper alloys |
| Wrought Alloys | |
| C10100-C15760 | Pure and Low Alloyed Copper (>99%Cu) |
| C16200-C16500 | Cadmium Copper |
| C17000-C17700 | Copper-Beryllium Alloy (Beryllium Bronzes) |
| C18000-C19900 | Copper and High Copper Alloys (>96%Cu) |
| C20500-C29800 | Brasses (Cu-Zn) |
| C31000-C35600 | Leaded Brasses (Cu-Zn-Pb ) |
| C40400-C49080 | Tin Brasses (Cu-Zn-Sn-Pb) |
| C50100-C52900 | Phosphor bronzes (Cu-Sn-P) |
| C53200-C54800 | Leaded Phosphor Bronzes |
| C55180-C56000 | Cu-Ag-P and Cu-P Brazing Filler Metal |
| C60600-C64400 | Aluminum Bronzes |
| C64700-C66100 | Silicon Bronzes |
| C66200-C66420 | Copper Alloys |
| C66700-C67820 | Manganese Bronzes |
| C68000-C69950 | Silicon Brasses and Other Copper-Zinc Alloys |
| C70100-C72950 | Copper-Nickel Alloys |
| C73150-C79900 | Nickel Silvers and Leaded Nickel Silvers |
| Cast alloys | |
| C80100-C81200 | Cast Coppers (>99%Cu) |
| C81300-C82800 | Cast Chromium Copper and Beryllium Copper Alloys (>96%Cu) |
| C83300-C85800 | Cast Red, Yellow and Leaded Brasses |
| C86100-C86800 | Cast Manganese Bronzes and Leaded Manganese Bronzes |
| C87300-C87900 | Cast Silicon Brasses and Bronzes |
| C89320-C89940 | Cast Cu-Sn-Bi-(Se, Zn, Ni) Alloys |
| C90200-C94500 | Tin Bronzes and Leaded Tin Bronzes |
| C94700-C94900 | Cast Nickel-Tin Bronzes |
| C95200-C95810 | Cast Aluminum Bronzes |
| C96200-C96800 | Cast Copper-Nickel Alloys |
| C97300-C97800 | Cast Nickel-Silver Alloys |
| C98200-C98840 | Cast Leaded Copper Alloys |
| C99300-C99750 | Cast Copper Alloys |
| E00001-E99999 | Rare earth and rare earth-like metals and alloys |
| E00000-E00999 | Actinium |
| EO1000-E20999 | Cerium |
| E21000-E45999 | Mixed rare earths |
| E46000-E47999 | Dysprosium |
| E48000-E49999 | Erbium |
| E50000-E51999 | Europium |
| E52000-E55999 | Gadolinium |
| E56000-E57999 | Holmium |
| E58000-E67999 | Lanthanum |
| E68000-E68999 | Lutetium |
| E69000-E73999 | Neodymium |
| E74000-E77999 | Praseodymium |
| E78000-E78999 | Promethium |
| E79000-E82999 | Samarium |
| E83000-E84999 | Scandium |
| E85000-E86999 | Terbium |
| E87000-E87999 | Thulium |
| E88000-E89999 | Ytterbium |
| E90000-E99999 | Yttrium |
| L00001-L99999 | Low-melting metals and alloys |
| L00001-L00999 | Bismuth |
| L01001-L01999 | Cadmium |
| L02001-L02999 | Cesium |
| L03001-L03999 | Gallium |
| L04001-L04999 | Indium |
| L06001-L06999 | Lithium |
| L07001-L07999 | Mercury |
| L08001-L08999 | Potassium |
| L09001-L09999 | Rubidium |
| L10001-L10999 | Selenium |
| L11001-L11999 | Sodium |
| L13001-L13999 | Tin |
| L50001-L59999 | Lead |
| M00001-M99999 | Miscellaneous nonferrous metals and alloys |
| M00001-M00999 | Antimony |
| M01001-M01999 | Arsenic |
| M02001-M02999 | Barium |
| M03001-M03999 | Calcium |
| M04001-M04999 | Germanium |
| M05001-M05999 | Plutonium |
| M06001-M06999 | Strontium |
| M07001-M07999 | Tellurium |
| M08001-M08999 | Uranium |
| M10001-M19999 | Magnesium |
| M20001-M29999 | Manganese |
| M30001-M39999 | Silicon |
| P00001-P99999 | Precious metals and alloys |
| P00001-P00999 | Gold |
| P01001-P01999 | Iridium |
| P02001-P02999 | Osmium |
| P03001-P03999 | Palladium |
| P04001-P04999 | Platinum |
| P05001-P05999 | Rhodium |
| P06001-P06999 | Ruthenium |
| P07001-P07999 | Silver |
| R00001-R99999 | Reactive and refractory metals and alloys |
| R01001-R01999 | Boron |
| R02001.R02999 | Hafnium |
| R03001-R03999 | Molybdenum |
| R04001.R04999 | Niobium (Columbium) |
| R05001-R05999 | Tantalum |
| R06001-R06999 | Thorium |
| R07001.R07999 | Tungsten |
| R08001-R08999 | Vanadium |
| R10001.R19999 | Beryllium |
| R20001-R29999 | Chromium |
| R30001.R39999 | Cobalt |
| R40001.R49999 | Rhenium |
| R50001-R59999 | Titanium |
| R60001-R69999 | Zirconium |
| W00001-W99999 | Welding filler metals, classified by weld deposit composition |
| W60000-W69999 | Copper base alloys |
| W70000-W79999 | Surfacing alloys |
| W80000-W89999 | Nickel base alloys |
| Z00001-Z99999 | Zinc and zinc alloys |
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