Stainless steel

Stainless Steel

	Email		Print
	Bookmark		Link

Stainless steel

In metallurgy

Metallurgy

Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic Chemical element, their intermetallics, and their mixtures, which are called alloys....
, stainless steel is defined as a steel

Steel

Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight , depending on grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten....
alloy

Alloy

An alloy is a partial or complete solid solution of one or more chemical element in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history....
with a minimum of 10% chromium

Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is a steely-gray, Lustre , hard metal that takes a high polish and has a high melting point....
content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel (it stains less), but it is not stain-proof. It is also called corrosion-resistant steel or CRES when the alloy type and grade are not detailed, particularly in the aviation industry.

Discussion

Ask a question about 'Stainless steel'

Start a new discussion about 'Stainless steel'

Answer questions from other users

Full Discussion Forum

History

A few corrosion-resistant iron artifacts survive from antiquity. A famous (and very large) example is the Iron Pillar of Delhi, erected by order of Kumara Gupta I

Kumara Gupta I

'Kumaragupta I' was ruler of the Gupta Empire from 415-455 Common Era. Like his father and predecessor, Chandragupta II, Kumaragupta was an able ruler....
around the year AD 400

400

Sorry, no overview for this topic
. Unlike stainless steel, however, these artifacts owe their durability not to chromium, but to their high phosphorus

Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the and . A Valency nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate minerals....
content, which, together with favorable local weather conditions, promotes the formation of a solid protective passivation layer of iron oxide

Iron oxide

Iron oxides are chemical compounds composed of iron and oxygen. Altogether, there are sixteen known iron oxides and oxyhydroxides....
s and phosphate

Phosphate

A phosphate, an inorganic chemical, is a Salt of phosphoric acid. Inorganic phosphates are mining to obtain phosphorus for use in agriculture and industry....
s, rather than the non-protective, cracked rust

Rust

Rust is a general term for a series of iron oxides, usually red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture....
layer that develops on most ironwork.

The corrosion resistance of iron-chromium alloys was first recognized in 1821 by the French

France

France , officially the French Republic , is a country whose Metropolitan France is located in Western Europe and that also comprises various Overseas departments and territories of France....
metallurgist Pierre Berthier

Pierre Berthier

Pierre Berthier was a France geologist and mining engineering.Pierre Berthier was born in Nemours. After studying at the ?cole Polytechnique, he went to the ?cole des Mines, where he became chief of the laboratory in 1816....
, who noted their resistance against attack by some acids and suggested their use in cutlery

Cutlery

Cutlery refers to any hand implement used in preparing, serving, and especially eating food in the Western world. It is more usually known as Silver or flatware in the United States, where cutlery can have the more specific meaning of knives and other cutting instruments....
. Metallurgists of the 19th century, however, were unable to produce the combination of low carbon and high chromium found in most modern stainless steels, and the high-chromium alloys they could produce were too brittle to be practical.

In the late 1890s, Hans Goldschmidt

Hans Goldschmidt

Johannes Wilhelm 'Goldschmidt' was a Germany chemist.Born in Berlin, he was a student of Robert Bunsen. His father, Theodor Goldschmidt, was the founder of the chemical company Chemische Fabrik Th....
of Germany

Germany

Germany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium, and the Netherlands....
developed an aluminothermic (thermite

Thermite

Thermite is a pyrotechnic composition of a metal powder and a metal oxide, which produces an aluminothermic reaction known as a thermite reaction....
) process for producing carbon-free chromium. In the years 1904–1911 several researchers, particularly Leon Guillet of France, prepared alloys that would today be considered stainless steel.

Friedrich Krupp Germaniawerft

Friedrich Krupp Germaniawerft

Friedrich Krupp Germaniawerft was a Germany shipbuilding company, located in the harbour at Kiel, and one of the largest and most important builders of U-boats for the Kaiserliche Marine in World War I and the Kriegsmarine in World War II....
built the 366-ton sailing yacht Germania featuring a chrome-nickel steel hull in Germany in 1908. In 1911, Philip Monnartz reported on the relationship between the chromium content and corrosion resistance. On October 17, 1912, Krupp

Krupp

The Krupp family, a prominent 400-year-old Germany dynasty from Essen, have become famous for their steel production and for their manufacture of ammunition and armaments....
engineers Benno Strauss and Eduard Maurer patented austenitic

Austenite

Austenite is a metallic non-magnetic solid solution of iron and an alloying element. In plain-carbon steel, austenite exists above the critical eutectoid temperature of 1000 K ; other alloys of steel have different eutectoid temperatures....
stainless steel.

Similar developments were taking place contemporaneously in the United States, where Christian Dantsizen and Frederick Becket were industrializing ferritic

Ferrite (iron)

Ferrite or alpha iron is a materials science term for iron, or a solid solution with iron as the main constituent, with a body centred cubic crystal structure....
stainless.

In 1913, Harry Brearley

Harry Brearley

Harry Brearley is usually credited with the invention of "rustless steel" , although Krupp filed a patent for its brand of Nirosta a few months before Brearley's breakthrough....
of the Brown-Firth

Firth Brown Steels

In 1902 Sheffield steelmakers John Brown and Company exchanged shares and came to a working agreement with neighbouring company Thomas Firth & Sons....
research laboratory in Sheffield, England, while seeking an erosion-resistant alloy for gun barrels, discovered and subsequently industrialized a martensitic

Martensite

Martensite, named after the German :category:metallurgists Adolf Martens , most commonly refers to a very hard form of steel crystalline structure, but it is also any crystal structure that is formed by displacive transformation....
stainless steel alloy. The discovery was announced two years later in a January 1915 newspaper article in The New York Times
The New York Times

The New York Times is an American daily newspaper published in New York City. The largest metropolitan newspaper in the United States, "The Gray Lady"?named for its staid appearance and style?is regarded as a national newspaper of record....
. This was later marketed under the "Staybrite" brand by Firth Vickers

Vickers

Vickers was a famous name in British engineering that existed through many companies from 1828 until 2004....
in England and was used for the new entrance canopy for the Savoy Hotel

Savoy Hotel

The Savoy Hotel is a five-star hotel located in the Strand, London, in the City of Westminster in central London that opened on 6 August 1889. The hotel remains one of London's most prestigious and opulent hotels, with 263 rooms and panoramic views of the River Thames across Savoy Place and the Victoria Embankment, part of the Thames Embankm...
in 1929 in London

London

London is the capital of both England and the United Kingdom, and the most populous municipality in the European Union. An important settlement for two millennia, History of London goes back to its founding by the Roman Empire....
.

Properties

High oxidation-resistance in air

Earth's atmosphere

The Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. Dry air contains roughly 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% Carbon dioxide in the Earth's atmosphere, and trace amounts of other gases....
at ambient temperature

Temperature

In physics, temperature is a physical property of a Physical system that underlies the common notions of hot and cold; something that feels hotter generally has the greater temperature....
are normally achieved with additions of a minimum of 13% (by weight) chromium

Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is a steely-gray, Lustre , hard metal that takes a high polish and has a high melting point....
, and up to 26% is used for harsh environments. The chromium forms a passivation

Passivation

Passivation is the process of making a material "passive" in relation to another material prior to using the materials together. For example, prior to storing hydrogen peroxide in an aluminium container, the container can be passivated by rinsing it with a dilute solution of nitric acid and peroxide alternating with deionized water....
layer of chromium(III) oxide

Chromium(III) oxide

Chromium oxide is the inorganic compound of the Chemical formula Cr2O3. It is one of principal oxides of chromium and is used as a pigment....
(Cr₂O₃) when exposed to oxygen

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
. The layer is too thin to be visible, and the metal remains lustrous. It is impervious to water

Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
and air, protecting the metal beneath. Also, this layer quickly reforms when the surface is scratched. This phenomenon is called passivation

Passivation

Aluminium

Aluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13....
and titanium

Titanium

Titanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the ?space age metal?, it has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver colour....
. Corrosion resistance can however be adversely affected if the component is used in a non-oxygenated environment, a typical example being underwater keel-bolts buried in timber.

When stainless steel parts such as nut

Nut (hardware)

A nut is a type of hardware fastener with a screw thread hole. Nuts are almost always used opposite a mating screw#Bolt to fasten a stack of parts together....
s and bolt

Screw

A screw is a shaft with a helix groove or screw thread formed on its surface and provision at one end to turn the screw. Its main uses are as a threaded fastener used to hold objects together, and as a simple machine used to translate torque into linear force....
s are forced together, the oxide layer can be scraped off causing the parts to weld

Welding

Welding is a fabrication or sculpture process that joins materials, usually metals or thermoplastics, by causing coalescence . This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes used in conjunction with heat, or by itself,...
together. When disassembled, the welded material may be torn and pitted, an effect that is known as galling

Galling

Galling, according to ASTM standard G40 , is: ?a form of surface damage arising between sliding solids, distinguished by microscopic, usually localized, roughening and creation of protrusions above the original surface?....
. This destructive galling can be best avoided by the use of dissimilar materials, e.g. bronze to stainless steel, or even different types of stainless steels (martensitic

Martensite

Austenite

Austenite is a metallic non-magnetic solid solution of iron and an alloying element. In plain-carbon steel, austenite exists above the critical eutectoid temperature of 1000 K ; other alloys of steel have different eutectoid temperatures....
, etc.), when metal-to-metal wear is a concern. In addition, Nitronic alloys (trademark of Armco, Inc.) reduce the tendency to gall through selective alloying with manganese and nitrogen.

Nickel

Nickel

Nickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge....
also contributes to passivation, as do other less commonly used ingredients such as molybdenum

Molybdenum

Molybdenum , is a Group 6 element chemical element with the symbol Mo and atomic number 42. It has the List of elements by melting point melting point of any element....
and vanadium

Vanadium

Vanadium is the chemical element with the symbol V and atomic number 23. It is a soft, silvery grey, ductile transition metal. The formation of an oxide layer stabilizes the metal against oxidation....
.

Applications

Stainless steel’s resistance to corrosion

Corrosion

Corrosion means the breaking down of essential properties in a material due to chemical reactions with its surroundings. In the most common use of the word, this means a loss of electrons of metals reacting with water and oxygen....
and staining, low maintenance, relatively low cost, and familiar luster make it an ideal base material for a host of commercial applications. There are over 150 grades of stainless steel, of which fifteen are most common. The alloy is milled

Steel mill

A steel mill is an industrial plant for the manufacture of steel.Steel is an alloy of iron and carbon. It is produced in a two-stage process....
into coils, sheets, plates, bars, wire, and tubing to be used in cookware, cutlery

Cutlery

Hardware

Hardware is a general term that refers to the physical cultural artifacts of a technology. It may also mean the physical components of a computer system, in the form of computer hardware....
, surgical instruments

Surgical instruments

A surgical instrument is a specially designed tool or device for performing specific actions of carrying out desired effects during a surgery or operation, such as modifying biological tissue, or to provide access for viewing it....
, major appliances, industrial equipment, and as an automotive and aerospace structural alloy and construction material in large buildings. Storage tanks and tankers used to transport orange juice

Orange juice

Orange juice is a popular beverage. It is a source of vitamin C , potassium, folic acid . Citrus juices also contain flavonoids that are believed to have beneficial health effects....
and other food are often made of stainless steel, due to its corrosion resistance and antibacterial properties. This also influences its use in commercial kitchens and food processing plants, as it can be steam cleaned, sterilized

Sterilization (microbiology)

Sterilization refers to any process that effectively kills or eliminates transmissible agents from a surface, equipment, article of food or medication, or biological culture medium....
, and does not need painting or application of other surface finishes.

Stainless steel is also used for jewellery and watches. The most common stainless steel alloy used for this is 316L. It can be re-finished by any jeweller and will not oxidize or turn black.

Some firearms incorporate stainless steel components as an alternative to blued or parkerized steel. A few more expensive revolvers like the Smith and Wesson Model 60 are milled entirely from stainless steel. This gives a high-luster finish similar in appearance to nickel plating but, unlike plating, not subject to rust when scratched.

Uses in sculpture, building facades and building structures

Stainless steel was in vogue during the art deco
Art Deco

Art Deco was a popular international design movement from 1925 until 1939, affecting the decorative arts such as architecture, interior design, and industrial design, as well as the visual arts such as fashion, painting, the graphic arts and film....
period. The most famous example of this is the upper portion of the Chrysler Building
Chrysler Building

The Chrysler Building is an Art Deco skyscraper in New York City, located on the east side of Manhattan in the Turtle Bay, Manhattan area at the intersection of 42nd Street and Lexington Avenue ....
(illustrated to the right). Diners and fast food restaurants feature large ornamental panels, stainless fixtures and furniture. Owing to the durability of the material, many of these buildings retain their original appearance.
The forging of stainless steel has given rise to a fresh approach to architectural blacksmith
Blacksmith

A blacksmith is a person who processess iron or steel by forging the metal; i.e., by using tools to hammer, bend, cut, and otherwise shape it in its non-liquid form....
ing in recent years.
The Gateway Arch (picture above) is clad entirely in stainless steel: 886 tons (804 metric tonne
Tonne

A tonne or metric ton , also referred to as a metric tonne, is a measurement of mass equal to 1,000 kilograms, or 2204.6226 pounds....
s) of plate, #3 finish, type 304 stainless steel.
Type 316 stainless is used on the exterior of both the Petronas Twin Towers
Petronas Twin Towers

The Petronas Twin Towers , in Kuala Lumpur, Malaysia are twin towers and were the world's tallest buildings, before being surpassed by Taipei 101....
and the Jin Mao Building
Jin Mao Building

The Jin Mao Tower is an 88-storey landmark supertall skyscraper in the Lujiazui area of the Pudong district of Shanghai, People's Republic of China....
, two of the world's tallest skyscraper
Skyscraper

A skyscraper is a tall, continuously habitable building. There is no official definition nor height above which a building may clearly be classified as a skyscraper....
s.
The Parliament House of Australia in Canberra
Parliament House, Canberra

File:Parliament House, Canberra.jpgParliament House is the meeting place of the Parliament of Australia. It is located in Canberra, the capital of Australia....
has a stainless steel flagpole weighing over 220 tons.
The aeration building in the Edmonton Composting Facility, the size of 14 hockey rinks, is the largest stainless steel building in North America.
The United States Air Force Memorial
United States Air Force Memorial

The United States Air Force Memorial honors the service of the personnel of the United States Air Force and its predecessors. The Memorial is located in Arlington, Virginia, on the grounds of Fort Myer near The Pentagon, at the intersection of Columbia Pike and South Joyce Street....
has an austenitic stainless steel structural skin.

Recycling & reuse

Stainless steel is 100% recyclable. In fact, an average stainless steel object is composed of about 60% recycled material, 25% originating from end-of-life products and 35% coming from manufacturing processes.

Types of stainless steel

There are different types of stainless steels: when nickel

Nickel

Nickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge....
is added, for instance, the austenite

Austenite

Austenite is a metallic non-magnetic solid solution of iron and an alloying element. In plain-carbon steel, austenite exists above the critical eutectoid temperature of 1000 K ; other alloys of steel have different eutectoid temperatures....
structure of iron is stabilized. This crystal structure makes such steels non-magnetic and less brittle

Brittle

A material is brittle if it is liable to fracture when subjected to stress . That is, it has little tendency to deform before fracture. This fracture absorbs relatively little energy, even in materials of high Strength of materials, and usually makes a snapping sound....
at low temperatures. For greater hardness and strength, carbon

Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
is added. When subjected to adequate heat treatment

Heat treatment

Heat treatment is a method used to alter the physical property, and sometimes chemical property, properties of a material. The most common application is metallurgy....
, these steels are used as razor

Razor

A razor is a bladed tool primarily used in the shaving off of unwanted body hair....
blades, cutlery

Cutlery

Tool

A broad definition of a tool is an entity used to interface between two or more domains that facilitates more effective action of one domain upon the other....
s, etc.

Significant quantities of manganese

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a Oxidation state in nature , and in many minerals....
have been used in many stainless steel compositions. Manganese preserves an austenitic structure in the steel as does nickel, but at a lower cost

Cost

In economics, business, retail, and accounting, a cost is the value of money that has been used up to produce something, and hence is not available for use anymore....
.

Stainless steels are also classified by their crystalline structure:

Austenitic
Austenite

Austenite is a metallic non-magnetic solid solution of iron and an alloying element. In plain-carbon steel, austenite exists above the critical eutectoid temperature of 1000 K ; other alloys of steel have different eutectoid temperatures....
, or 300 series, stainless steels comprise over 70% of total stainless steel production. They contain a maximum of 0.15% carbon, a minimum of 16% chromium and sufficient nickel and/or manganese to retain an austenitic structure at all temperatures from the cryogenic region to the melting point of the alloy. A typical composition of 18% chromium and 10% nickel, commonly known as 18/10 stainless, is often used in flatware. Similarly, 18/0 and 18/8 are also available. Superaustenitic stainless steels, such as alloy AL-6XN
AL-6XN

The AL-6XN alloy is a superaustenitic stainless steel which was developed by . It exhibits far greater resistance to chloride pitting, crevice corrosion and stress-corrosion cracking than exhibited by the standard 300 series stainless steels, and is less costly than the traditional nickel-base corrosion resistant alloys....
and 254SMO, exhibit great resistance to chloride pitting and crevice corrosion due to high molybdenum content (>6%) and nitrogen additions, and the higher nickel content ensures better resistance to stress-corrosion cracking versus the 300 series. The higher alloy content of superaustenitic steels makes them more expensive. Other steels can offer similar performance at lower cost and are preferred in certain applications.

The low carbon version of the Austenitic Stainless Steel, for example 316L or 304L, are used to avoid corrosion problem caused by welding. The "L" means that the carbon content of the Stainless Steel is below 0.03%, this will reduce the sensitization effect, precipitation of Chromium Carbides at grain boundaries, due to the high temperature produced by welding operation.

Ferritic
Ferrite (iron)

Ferrite or alpha iron is a materials science term for iron, or a solid solution with iron as the main constituent, with a body centred cubic crystal structure....
stainless steels are highly corrosion-resistant, but less durable than austenitic grades. They contain between 10.5% and 27% chromium and very little nickel, if any, but some types can contain lead. Most compositions include molybdenum
Molybdenum

Molybdenum , is a Group 6 element chemical element with the symbol Mo and atomic number 42. It has the List of elements by melting point melting point of any element....
; some, aluminium or titanium
Titanium

Titanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the ?space age metal?, it has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver colour....
. Common ferritic grades include 18Cr-2Mo, 26Cr-1Mo, 29Cr-4Mo, and 29Cr-4Mo-2Ni. These alloys can be degraded by the presence of chromium, a intermetallic phase which can precipitate upon welding.

Martensitic
Martensite

Martensite, named after the German :category:metallurgists Adolf Martens , most commonly refers to a very hard form of steel crystalline structure, but it is also any crystal structure that is formed by displacive transformation....
stainless steels are not as corrosion-resistant as the other two classes but are extremely strong and tough, as well as highly machineable
Machining

Conventional machining, one of the most important material removal methods, is a collection of material-working processes in which power-driven machine tools, such as Lathe s, milling machines, and drill presses are used with a sharp cutting tool to mechanically cut the material to achieve the desired geometry....
, and can be hardened by heat treatment. Martensitic stainless steel contains chromium
Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is a steely-gray, Lustre , hard metal that takes a high polish and has a high melting point....
(12-14%), molybdenum
Molybdenum

Molybdenum , is a Group 6 element chemical element with the symbol Mo and atomic number 42. It has the List of elements by melting point melting point of any element....
(0.2-1%), nickel
Nickel

Nickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge....
(0-<2%), and carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
(about 0.1-1%) (giving it more hardness but making the material a bit more brittle). It is quenched and magnetic.

Precipitation-hardening martensitic stainless steels have corrosion resistance comparable to austenitic varieties, but can be precipitation hardened to even higher strengths than the other martensitic grades. The most common, 17-4PH, uses about 17% chromium and 4% nickel. There is a rising trend in defense budgets to opt for an ultra-high-strength stainless steel when possible in new projects, as it is estimated that 2% of the US GDP is spent dealing with corrosion. The Lockheed-Martin Joint Strike Fighter is the first aircraft to use a precipitation-hardenable stainless steel—Carpenter Custom 465—in its airframe.

Duplex stainless steels have a mixed microstructure of austenite and ferrite, the aim being to produce a 50/50 mix, although in commercial alloys, the mix may be 40/60 respectively. Duplex steels have improved strength over austenitic stainless steels and also improved resistance to localised corrosion, particularly pitting, crevice corrosion and stress corrosion cracking. They are characterised by high chromium (19–28%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. The most used Duplex Stainless Steel are the 2205 (22% Chromium, 5% Nickel) and 2507 (25% Chromium, 7% Nickel); the 2507 is also known as "SuperDuplex" due to its higher corrosion resistance.

Comparison of standardized steels

EN-standard Steel no. k.h.s DIN	EN-standard Steel name	SAE grade	UNS Unified numbering system The unified numbering system is an alloy designation system widely accepted in North America. It consists of a prefix letter and five digits designating a material composition....
		440A	S44002
1.4112		440B	S44003
1.4125		440C	S44004
		440F	S44020
1.4016	X6Cr17	430	S43000
1.4512	X6CrTi12	409	S40900
		410	S41000
1.4310	X10CrNi18-8	301	S30100
1.4318	X2CrNiN18-7	301LN	N/A
1.4307	X2CrNi18-9	304L	S30403
1.4306	X2CrNi19-11	304L	S30403
1.4311	X2CrNiN18-10	304LN	S30453
1.4301	X5CrNi18-10	304	S30400
1.4948	X6CrNi18-11	304H	S30409
1.4303	X5CrNi18-12	305	S30500
	X5CrNi30-9	312
1.4541	X6CrNiTi18-10	321	S32100
1.4878	X12CrNiTi18-9	321H	S32109
1.4404	X2CrNiMo17-12-2	316L	S31603
1.4401	X5CrNiMo17-12-2	316	S31600
1.4406	X2CrNiMoN17-12-2	316LN	S31653
1.4432	X2CrNiMo17-12-3	316L	S31603
1.4435	X2CrNiMo18-14-3	316L	S31603
1.4436	X3CrNiMo17-13-3	316	S31600
1.4571	X6CrNiMoTi17-12-2	316Ti	S31635
1.4429	X2CrNiMoN17-13-3	316LN	S31653
1.4438	X2CrNiMo18-15-4	317L	S31703
1.4539	X1NiCrMoCu25-20-5	904L	N08904
1.4547	X1CrNiMoCuN20-18-7	N/A	S31254

Stainless steel grades

100 Series—austenitic chromium-nickel-manganese alloys

Type 101—austenitic that is hardenable through cold working for furniture
Type 102—austenitic general purpose stainless steel working for furniture

200 Series—austenitic chromium-nickel-manganese alloys

Type 201—austenitic that is hardenable through cold working
Type 202—austenitic general purpose stainless steel

300 Series—austenitic chromium-nickel alloys

Type 301—highly ductile, for formed products. Also hardens rapidly during mechanical working. Good weldability. Better wear resistance and fatigue strength than 304.
Type 302—same corrosion resistance as 304, with slightly higher strength due to additional carbon.
Type 303—free machining version of 304 via addition of sulfur
Sulfur

Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant Valence non-metal....
and phosphorus
Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the and . A Valency nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate minerals....
. Also referred to as "A1" in accordance with ISO 3506.
Type 304—the most common grade; the classic 18/8 stainless steel. Also referred to as "A2" in accordance with ISO 3506.
Type 304L— same as the 304 grade but contains less carbon to increase weldability. Is slightly weaker than 304.
Type 304LN—same as 304L, but also nitrogen is added to obtain a much higher yield and tensile strength than 304L.
Type 308—used as the filler metal when welding 304
Type 309—better temperature resistance than 304, also sometimes used as filler metal when welding dissimilar steels, along with inconel
Inconel

Inconel is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys . Inconel alloys are typically used in high temperature applications....
.
Type 316—the second most common grade (after 304); for food and surgical stainless steel
Surgical stainless steel

Surgical stainless steel is a specific type of stainless steel, used in medical applications.The chromium gives the metal its scratch-resistance and corrosion resistance....
uses; alloy addition of molybdenum prevents specific forms of corrosion. It is also known as marine grade stainless steel due to its increased resistance to chloride corrosion compared to type 304. 316 is often used for building nuclear reprocessing
Nuclear reprocessing

Nuclear reprocessing separates components of spent nuclear fuel such as:...
plants. 316L is an extra low carbon grade of 316, generally used in stainless steel watches and marine applications due to its high resistance to corrosion. Also referred to as "A4" in accordance with ISO 3506. 316Ti includes titanium for heat resistance, therefore it is used in flexible chimney liners.
Type 321—similar to 304 but lower risk of weld decay due to addition of titanium. See also 347 with addition of niobium for desensitization during welding.

400 Series—ferritic and martensitic chromium alloys

Type 405— ferritic for welding applications
Type 408—heat-resistant; poor corrosion resistance; 11% chromium, 8% nickel.
Type 409—cheapest type; used for automobile
Automobile

An automobile or motor car is a wheeled motor vehicle for transportation passengers, which also carries its own car engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally f...
exhausts; ferritic (iron/chromium only).
Type 410—martensitic (high-strength iron/chromium). Wear-resistant, but less corrosion-resistant.
Type 416—easy to machine due to additional sulfur
Type 420—Cutlery Grade martensitic; similar to the Brearley's original rustless steel. Excellent polishability.
Type 430—decorative, e.g., for automotive trim; ferritic. Good formability, but with reduced temperature and corrosion resistance.
Type 439—ferritic grade, a higher grade version of 409 used for catalytic converter exhaust sections. Increased chromium for improved high temperature corrosion/oxidation resistance.
Type 440—a higher grade of cutlery steel, with more carbon, allowing for much better edge retention when properly heat-treated. It can be hardened to approximately Rockwell
Rockwell scale

The Rockwell scale is a hardness scale based on the indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload....
58 hardness, making it one of the hardest stainless steels. Due to its toughness and relatively low cost, most display-only and replica swords or knives are made of 440 stainless. Also known as razor blade steel. Available in four grades: 440A, 440B, 440C, and the uncommon 440F (free machinable). 440A, having the least amount of carbon in it, is the most stain-resistant; 440C, having the most, is the strongest and is usually considered more desirable in knifemaking than 440A, except for diving or other salt-water applications.
Type 446—For elevated temperature service

500 Series—heat-resisting chromium alloys
600 Series—martensitic precipitation hardening alloys

601 through 604: Martensitic low-alloy steels.
610 through 613: Martensitic secondary hardening steels.
614 through 619: Martensitic chromium steels.
630 through 635: Semiaustenitic and martensitic precipitation-hardening stainless steels.

Type 630 is most common PH stainless, better known as 17-4; 17% chromium, 4% nickel.

650 through 653: Austenitic steels strengthened by hot/cold work.
660 through 665: Austenitic superalloys; all grades except alloy 661 are strengthened by second-phase precipitation.

Type 2205— the most widely used duplex (ferritic/austenitic) stainless steel grade. It has both excellent corrosion resistance and high strength.

Stainless steel designations
SAE designation	UNS designation	% Cr	% Ni	% C	% Mn	% Si	% P	% S	% N	Other
Austenitic
201	S20100	16–18	3.5–5.5	0.15	5.5–7.5	0.75	0.06	0.03	0.25	-
202	S20200	17–19	4–6	0.15	7.5–10.0	0.75	0.06	0.03	0.25	-
205	S20500	16.5–18	1–1.75	0.12–0.25	14–15.5	0.75	0.06	0.03	0.32–0.40	-
301	S30100	16–18	6–8	0.15	2	0.75	0.045	0.03	-	-
302	S30200	17–19	8–10	0.15	2	0.75	0.045	0.03	0.1	-
302B	S30215	17–19	8–10	0.15	2	2.0–3.0	0.045	0.03	-	-
303	S30300	17–19	8–10	0.15	2	1	0.2	0.15 min	-	Mo 0.60 (optional)
303Se	S30323	17–19	8–10	0.15	2	1	0.2	0.06	-	0.15 Se min
304	S30400	18–20	8–10.50	0.08	2	0.75	0.045	0.03	0.1	-
304L	S30403	18–20	8–12	0.03	2	0.75	0.045	0.03	0.1	-
304Cu	S30430	17–19	8–10	0.08	2	0.75	0.045	0.03	-	3–4 Cu
304N	S30451	18–20	8–10.50	0.08	2	0.75	0.045	0.03	0.10–0.16	-
305	S30500	17–19	10.50–13	0.12	2	0.75	0.045	0.03	-	-
308	S30800	19–21	10–12	0.08	2	1	0.045	0.03	-	-
309	S30900	22–24	12–15	0.2	2	1	0.045	0.03	-	-
309S	S30908	22–24	12–15	0.08	2	1	0.045	0.03	-	-
310	S31000	24–26	19–22	0.25	2	1.5	0.045	0.03	-	-
310S	S31008	24–26	19–22	0.08	2	1.5	0.045	0.03	-	-
314	S31400	23–26	19–22	0.25	2	1.5–3.0	0.045	0.03	-	-
316	S31600	16–18	10–14	0.08	2	0.75	0.045	0.03	0.10	2.0–3.0 Mo
316L	S31603	16–18	10–14	0.03	2	0.75	0.045	0.03	0.10	2.0–3.0 Mo
316F	S31620	16–18	10–14	0.08	2	1	0.2	0.10 min	-	1.75–2.50 Mo
316N	S31651	16–18	10–14	0.08	2	0.75	0.045	0.03	0.10–0.16	2.0–3.0 Mo
317	S31700	18–20	11–15	0.08	2	0.75	0.045	0.03	0.10 max	3.0–4.0 Mo
317L	S31703	18–20	11–15	0.03	2	0.75	0.045	0.03	0.10 max	3.0–4.0 Mo
321	S32100	17–19	9–12	0.08	2	0.75	0.045	0.03	0.10 max	Ti 5(C+N) min, 0.70 max
329	S32900	23–28	2.5–5	0.08	2	0.75	0.04	0.03	-	1–2 Mo
330	N08330	17–20	34–37	0.08	2	0.75–1.50	0.04	0.03	-	-
347	S34700	17–19	9–13	0.08	2	0.75	0.045	0.030	-	Nb + Ta, 10 x C min, 1 max
348	S34800	17–19	9–13	0.08	2	0.75	0.045	0.030	-	Nb + Ta, 10 x C min, 1 max, but 0.10 Ta max; 0.20 Ca
384	S38400	15–17	17–19	0.08	2	1	0.045	0.03	-	-
Ferritic
405	S40500	11.5–14.5	-	0.08	1	1	0.04	0.03	-	0.1–0.3 Al, 0.60 max
409	S40900	10.5–11.75	0.05	0.08	1	1	0.045	0.03	-	Ti 6 x C, but 0.75 max
429	S42900	14–16	0.75	0.12	1	1	0.04	0.03	-	-
430	S43000	16–18	0.75	0.12	1	1	0.04	0.03	-	-
430F	S43020	16–18	-	0.12	1.25	1	0.06	0.15 min	-	0.60 Mo (optional)
430FSe	S43023	16–18	-	0.12	1.25	1	0.06	0.06	-	0.15 Se min
434	S43400	16–18	-	0.12	1	1	0.04	0.03	-	0.75–1.25 Mo
436	S43600	16–18	-	0.12	1	1	0.04	0.03	-	0.75–1.25 Mo; Nb+Ta 5 x C min, 0.70 max
442	S44200	18–23	-	0.2	1	1	0.04	0.03	-	-
446	S44600	23–27	0.25	0.2	1.5	1	0.04	0.03	-	-
Martensitic
403	S40300	11.5–13.0	0.60	0.15	1	0.5	0.04	0.03	-	-
410	S41000	11.5–13.5	0.75	0.15	1	1	0.04	0.03	-	-
414	S41400	11.5–13.5	1.25–2.50	0.15	1	1	0.04	0.03	-	-
416	S41600	12–14	-	0.15	1.25	1	0.06	0.15 min	-	0.060 Mo (optional)
416Se	S41623	12–14	-	0.15	1.25	1	0.06	0.06	-	0.15 Se min
420	S42000	12–14	-	0.15 min	1	1	0.04	0.03	-	-
420F	S42020	12–14	-	0.15 min	1.25	1	0.06	0.15 min	-	0.60 Mo max (optional)
422	S42200	11.0–12.5	0.50–1.0	0.20–0.25	0.5–1.0	0.5	0.025	0.025	-	0.90–1.25 Mo; 0.20–0.30 V; 0.90–1.25 W
431	S41623	15–17	1.25–2.50	0.2	1	1	0.04	0.03	-	-
440A	S44002	16–18	-	0.60–0.75	1	1	0.04	0.03	-	0.75 Mo
440B	S44003	16–18	-	0.75–0.95	1	1	0.04	0.03	-	0.75 Mo
440C	S44004	16–18	-	0.95–1.20	1	1	0.04	0.03	-	0.75 Mo
Heat resisting
501	S50100	4–6	-	0.10 min	1	1	0.04	0.03	-	0.40–0.65 Mo
502	S50200	4–6	-	0.1	1	1	0.04	0.03	-	0.40–0.65 Mo
Martensitic precipitation hardening
630	S17400	15-17	3-5	0.07	1	1	0.04	0.03	-	Cu 3-5, Ta 0.15-0.45

Stainless steel finishes

Standard mill finishes can be applied to flat rolled stainless steel directly by the rollers and by mechanical abrasives. Steel is first rolled to size and thickness and then annealed

Annealing (metallurgy)

Annealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness....
to change the properties of the final material. Any oxidation that forms on the surface (scale) is removed by pickling

Pickling (metal)

Pickling is a treatment of metallic surfaces in order to remove impurities, stains, rust or Fouling with a solution called pickle liquor, containing strong acids, before subsequent processing, such as extrusion, rolling, painting, galvanization or plating with tin or chromium....
, and the passivation layer is created on the surface. A final finish can then be applied to achieve the desired aesthetic appearance.

No. 0 - Hot rolled, annealed, thicker plates
No. 1 - Hot rolled, annealed and passivated
No. 2D - Cold rolled, annealed, pickled and passivated
No. 2B - Same as above with additional pass-through highly polished rollers
No. 2BA - Bright annealed (BA or 2R) same as above then Bright annealed under Oxygen-free atmospheric conditions
No. 3 - Coarse abrasive finish applied mechanically
No. 4 - Brushed finish
No. 5 - Satin finish
No. 6 - Matte finish
No. 7 - Reflective finish
No. 8 - Mirror finish
No. 9 - Bead blast finish
No. 10 - heat colored finish-wide range of electropolished & heat colored surfaces

External links

by Specialty Steel Supply
by International Stainless Steel Forum
by The Stainless Steel Information Center
by BSSA
by Cambridge University

Stainless steel

History

Properties

Applications

Uses in sculpture, building facades and building structures

Recycling & reuse

Types of stainless steel

Comparison of standardized steels

Stainless steel grades

Stainless steel finishes

See also

Bibliography

External links