October 22, 2018

Unified Numbering System(UNS) for metals and alloys

The Unified Numbering System – UNS – was developed by ASTM and SAE to correlate different numbering systems for commercial metals and alloys.

The UNS number (Unified Numbering System) which was developed by ASTM and SAE,  is a systematic scheme in which each metal is designated by a letter followed by five numbers. It is a composition-based system of commercial materials and does not guarantee any performance specifications or exact composition with impurity limits. Other nomenclature systems have been incorporated into the UNS numbering system to minimize confusion.

For example, Aluminum 6061 (AA6061) is assigned UNS A96061. Likewise AISI 1018 steel becomes UNS G10180.
SS2205 isa assigned UNS J92205 (casting) and UNS S32205

The UNS number is not a specification – it is an identification number for a metal or alloy specified elsewhere. The UNS numbering categories are

Axxxxx – Aluminum Alloys
Cxxxxx – Copper Alloys, including Brass and Bronze
Fxxxxx – Iron, including Ductile Irons and Cast Irons

Stainless Steel 2205 Propeller

Stainless Steel 2205 Propeller

Gxxxxx – Carbon and Alloy Steels
Hxxxxx – Steels – AISI H Steels
Jxxxxx – Steels – Cast
Kxxxxx – Steels, including Maraging, Stainless Steel, HSLA, Iron-Base Superalloys
Lxxxxx – Low Melting Metals, including Lead and Tin Alloys, Babbit Alloys and Solder Alloys
M1xxxx – Magnesium Alloys
Nxxxxx – Nickel Alloys
Rxxxxx – Refractory Alloys
R03xxx- Molybdenum Alloys
R04xxx- Niobium (Columbium) Alloys
R05xxx- Tantalum Alloys
R3xxxx- Cobalt Alloys
R5xxxx- Titanium Alloys
R6xxxx- Zirconium Alloys
Sxxxxx – Stainless Steels, including Precipitation Hardening Stainless Steel and Iron-Based Superalloys
Txxxxx – Tool Steels
Zxxxxx – Zinc Alloys


UNS SeriesMetal Type
A00001 to A99999 2)Aluminum and aluminum alloys
C00001 to C99999 2)Copper and copper alloys
D00001 to D99999 1)Specified mechanical property steels
E00001 to E99999 2)Rare earth and rare earthlike metals and alloys
F00001 to F99999 1)Cast irons
G00001 to G99999 1)AISI and SAE carbon and alloy steels (except tool steels)
H00001 to H99999 1)AISI and SAE H-steels
J00001 to J99999Cast steels (except tool steels)
K00001 to K99999 1)Miscellaneous steels and ferrous alloys
L00001 to L99999 2)Low-melting metals and alloys
M00001 to M99999 2)Miscellaneous nonferrous metals and alloys
N00001 to N99999 2)Nickel and nickel alloys
P00001 to P99999 2)Precious metals and alloys
R00001 to R99999 2)Reactive and refractory metals and alloys
S00001 to S99999 1)Heat and corrosion resistant (stainless) steels
T00001 to T99999 1)Tool steels, wrought and cast
W00001 to W99999Welding filler metals
Z00001 to Z99999Zinc and zinc alloys
  1. Ferrous metals and alloys
  2. Nonferrous metals and alloys

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