UNS - Unified Numbering System

The Unified Numbering System (UNS) was developed by ASTM and SAE to correlate different numbering systems for commercial metals and alloys. The UNS number is an identification number that categorizes metals and alloys into 19 series, each representing different metal types and their compositions.

UNS SeriesMetal TypeCategory
A00001 to A99999Aluminum and aluminum alloysNonferrous
C00001 to C99999Copper and copper alloysNonferrous
D00001 to D99999Specified mechanical property steelsFerrous
E00001 to E99999Rare earth and rare earthlike metals and alloysNonferrous
F00001 to F99999Cast ironsFerrous
G00001 to G99999AISI and SAE carbon and alloy steels (except tool steels)Ferrous
H00001 to H99999AISI and SAE H-steelsFerrous
J00001 to J99999Cast steels (except tool steels)Ferrous
K00001 to K99999Miscellaneous steels and ferrous alloysFerrous
L00001 to L99999Low-melting metals and alloysNonferrous
M00001 to M99999Miscellaneous nonferrous metals and alloysNonferrous
N00001 to N99999Nickel and nickel alloysNonferrous
P00001 to P99999Precious metals and alloysNonferrous
R00001 to R99999Reactive and refractory metals and alloysNonferrous
S00001 to S99999Heat and corrosion resistant (stainless) steelsFerrous
T00001 to T99999Tool steels, wrought and castFerrous
W00001 to W99999Welding filler metalsFerrous
Z00001 to Z99999Zinc and zinc alloysNonferrous

Overview

The Unified Numbering System (UNS) provides a correlation between different commercial numbering systems for metals and alloys, developed jointly by ASTM and SAE.

Key Information

  • Purpose: Identification and classification of metals and alloys
  • Ferrous Metals and Alloys: Series D, F, G, H, J, K, S, T, W
  • Nonferrous Metals and Alloys: Series A, C, E, L, M, N, P, R, Z
  • Format: Each series contains 99,999 designations

The UNS number itself is not a specification but rather serves as a reference identifier that correlates to specifications defined elsewhere.