The Unified Numbering System for Metals and Alloys (UNS) is an alloy designation system widely accepted in North America. Each UNS number relates to a specific metal or alloy and defines its specific chemical composition, or in some cases a specific mechanical or physical property. A UNS number alone does not constitute a full material specification because it establishes no requirements for material properties, heat treatment, form, or quality.
During the early 20th century many different metal alloys were developed in isolation within certain industries to meet the needs of that industry. This allowed a wide variety of competing standards, compositions and designations to flourish. By the 1960s there were a number of differing numbering or designation schemes for various alloys. This meant that the same number might be used for different alloys, different numbers might be used for the same alloy or different trade names might indicate similar or wildly different alloys. Additionally, the increasing number of new alloys meant that the problem would only get worse. [1]
In January 1971, an 18-month study recommended that a unified system would be possible and helpful. An advisory board was established in April 1972 to establish the Unified Numbering System (UNS). [2] The UNS is managed jointly by the ASTM International and SAE International. The resulting document SAE HS-1086 provides a cross-reference between various designation systems and the chemical composition.
A UNS number only defines a specific chemical composition, it does not provided full material specification. Requirements such as material properties (yield strength, ultimate strength, hardness, etc.), heat treatment, form (rolled, cast, forged, flanges, tubes, bars, etc.), purpose (high temperature, boilers and pressure vessels, etc.) and testing methods are all specified in the material or standard specification which is created by various trade and professional organizations. Many material or standard specifications include a number of different UNS numbers that may be used within that specification.
For example: UNS S30400 (SAE 304, Cr/Ni 18/10, Euronorm 1.4301 stainless steel) could be used to make stainless steel bars (ASTM A276) or stainless steel plates for pressure vessels (ASTM A240) or pipes (ASTM A312). Conversely, A312 pipes could be made out of about 70 different UNS alloy steels.
It consists of a prefix letter and five digits designating a material composition. For example, a prefix of S indicates stainless steel alloys, C indicates copper, brass, or bronze alloys, T indicates tool steels, and so on. The first 3 digits often match older 3-digit numbering systems, while the last 2 digits indicate more modern variations.
For example, Stainless Steel Type 310 in the original 3-digit system became S31000 in the UNS System. The more modern low-carbon variation, Type 310S, became S31008 in the UNS System. Often, the suffix digit is chosen to represent a material property specification. For example, "08" was assigned to UNS S31008 because the maximum allowed carbon content is 0.08%.
UNS series | Metal type(s) |
---|---|
A00001 to A99999 | Aluminum and aluminum alloys |
C00001 to C99999 | Copper and copper alloys (brasses and bronzes) |
D00001 to D99999 | Specified mechanical property steels |
E00001 to E99999 | Rare earth and rare earthlike metals and alloys |
F00001 to F99999 | Cast irons |
G00001 to G99999 | AISI and SAE carbon and alloy steels (except tool steels) |
H00001 to H99999 | AISI and SAE H-steels |
J00001 to J99999 | Cast steels (except tool steels) |
K00001 to K99999 | Miscellaneous steels and ferrous alloys |
L00001 to L99999 | Low-melting metals and alloys |
M00001 to M99999 | Miscellaneous nonferrous metals and alloys
|
N00001 to N99999 | Nickel and nickel alloys |
P00001 to P99999 | Precious metals and alloys |
R00001 to R99999 | Refractory metals and alloys
|
S00001 to S99999 | Heat and corrosion resistant (stainless) steels |
T00001 to T99999 | Tool steels, wrought and cast |
W00001 to W99999 | Welding filler metals |
Z00001 to Z99999 | Zinc and zinc alloys |
Some common materials and translations to other standards: [5]
A UNS-derived system known as ISC (in Chinese 统一数字代号, literally "unified numeric designator") is used in China in parallel to the composition-based nomenclature. [6] Individual grades may receive the same number (e.g. S31603), a slightly different number (e.g. S30400/S30408, S17400/S17440), or a totally different one (e.g. S20200/S35450, S41026 [7] /S45710). [5]
Stainless steel, also known as inox, corrosion-resistant steel (CRES), and rustless steel, is an alloy of iron that is resistant to rusting and corrosion. It contains iron with chromium and other elements such as molybdenum, carbon, nickel and nitrogen depending on its specific use and cost. Stainless steel's resistance to corrosion results from the 10.5%, or more, chromium content which forms a passive film that can protect the material and self-heal in the presence of oxygen.
The American Iron and Steel Institute (AISI) is a trade association of North American steel producers. Including its predecessor organizations, it is one of the oldest trade associations in the United States, dating back to 1855. It assumed its present form in 1908, with Judge Elbert H. Gary, chairman of the United States Steel Corporation, as its first president. Its development was in response to the need for a cooperative agency in the iron and steel industry for collecting and disseminating statistics and information, carrying on investigations, providing a forum for the discussion of problems and generally advancing the interests of the industry.
Rebar, known when massed as reinforcing steel or steel reinforcement, is a steel bar used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. Concrete is strong under compression, but has low tensile strength. Rebar significantly increases the tensile strength of the structure. Rebar's surface features a continuous series of ribs, lugs or indentations to promote a better bond with the concrete and reduce the risk of slippage.
Surgical stainless steel is a grade of stainless steel used in biomedical applications. The most common "surgical steels" are austenitic SAE 316 stainless and martensitic SAE 440, SAE 420, and 17-4 stainless steels. There is no formal definition on what constitutes a "surgical stainless steel", so product manufacturers and distributors often apply the term to refer to any grade of corrosion resistant steel.
High-speed steel is a subset of tool steels, commonly used as cutting tool material.
Monel is a group of alloys of nickel and copper, with small amounts of iron, manganese, carbon, and silicon. Monel is not a cupronickel alloy because it has less than 60% copper.
In modern Western body piercing, a wide variety of materials are used. Some cannot be autoclaved, and others may induce allergic reactions, or harbour bacteria. Certain countries, such as those belonging to the EU, have legal regulations specifying which materials can be used in new piercings.
Alloy 20 is an austenitic stainless steel containing less than 50% iron developed for applications involving sulfuric acid. Its corrosion resistance also finds other uses in the chemical, petrochemical, power generation, and plastics industries. Alloy 20 resists pitting and chloride ion corrosion, better than 304 stainless steel and on par with 316L stainless steel. Its copper content protects it from sulfuric acid. Alloy 20 is often chosen to solve stress corrosion cracking problems, which may occur with 316L stainless. Alloy of the same name with the designation "Cb-3" indicates niobium stabilized.
Marine grade stainless alloys typically contain molybdenum to resist the corrosive effects of NaCl or salt in seawater. Concentrations of salt in seawater can vary, and splash zones can cause concentrations to increase dramatically from the spray and evaporation.
The SAE steel grades system is a standard alloy numbering system for steel grades maintained by SAE International.
Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties.
An aluminium alloy (UK/IUPAC) or aluminum alloy is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There are two principal classifications, namely casting alloys and wrought alloys, both of which are further subdivided into the categories heat-treatable and non-heat-treatable. About 85% of aluminium is used for wrought products, for example rolled plate, foils and extrusions. Cast aluminium alloys yield cost-effective products due to the low melting point, although they generally have lower tensile strengths than wrought alloys. The most important cast aluminium alloy system is Al–Si, where the high levels of silicon (4–13%) contribute to give good casting characteristics. Aluminium alloys are widely used in engineering structures and components where light weight or corrosion resistance is required.
Steel grades to classify various steels by their composition and physical properties have been developed by a number of standards organizations.
6061 aluminium alloy is a precipitation-hardened aluminium alloy, containing magnesium and silicon as its major alloying elements. Originally called "Alloy 61S", it was developed in 1935. It has good mechanical properties, exhibits good weldability, and is very commonly extruded. It is one of the most common alloys of aluminium for general-purpose use.
ASTM A325 is an ASTM International standard for heavy hex structural bolts, titled Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength. It defines mechanical properties for bolts that range from 1⁄2 to 1+1⁄2 inches in diameter.
A tube, or tubing, is a long hollow cylinder used for moving fluids or to protect electrical or optical cables and wires.
Zeron 100 is a super duplex stainless steel developed by Rolled Alloys. The alloy has excellent corrosion resistance combined with high strength. It typically contains 25% chromium and 7% nickel and 3.6% molybdenum along with copper and tungsten additions. Zeron 100 has a 50–50 austenitic–ferritic structure. It also has greater resistance to chloride pitting, crevice corrosion and stress corrosion cracking than exhibited by the standard 300 series stainless steels.
Ti-6Al-4V, also sometimes called TC4, Ti64, or ASTM Grade 5, is an alpha-beta titanium alloy with a high specific strength and excellent corrosion resistance. It is one of the most commonly used titanium alloys and is applied in a wide range of applications where low density and excellent corrosion resistance are necessary such as e.g. aerospace industry and biomechanical applications.
SAE 304 stainless steel is the most common stainless steel. It is an alloy of iron, carbon, chromium and nickel. It is an austenitic stainless steel, and is therefore not magnetic. It is less electrically and thermally conductive than carbon steel. It has a higher corrosion resistance than regular steel and is widely used because of the ease in which it is formed into various shapes.