In metallurgy, stainless steel, also known as inox steel or inox from French inoxydable, is a steel alloy with a minimum of 10.5% chromium content by mass.
Stainless steel
From Wikipedia, the free encyclopedia
In
metallurgy,
stainless steel, also known as
inox steel or
inox from
French inoxydable, is a
steel alloy with a minimum of 10.5%
[1] chromium content by mass.
Description
Stainless steel is used for corrosion-resistant tools such as this
nutcracker
Stainless steel does not readily
corrode,
rust or stain with water as ordinary steel does. However, it is not fully stain-proof in low-oxygen, high-
salinity, or poor air-circulation environments.
[2]
There are different grades and surface finishes of stainless steel to
suit the environment the alloy must endure. Stainless steel is used
where both the properties of steel and
corrosion resistance are required.
Stainless steel differs from
carbon steel by the amount of chromium present. Unprotected carbon steel
rusts readily when exposed to air and moisture. This
iron oxide
film (the rust) is active and accelerates corrosion by forming more
iron oxide; and, because of the greater volume of the iron oxide, this
tends to flake and fall away. Stainless steels contain sufficient
chromium to form a
passive film of
chromium oxide,
which prevents further surface corrosion by blocking oxygen diffusion
to the steel surface and blocks corrosion from spreading into the
metal's internal structure.
[3] Passivation occurs only if the proportion of chromium is high enough and oxygen is present.
Properties
Stainless steel is not completely immune to corrosion in this
desalination equipment
Oxidation
High oxidation resistance in
air at ambient
temperature is normally achieved with additions of a minimum of 13% (by weight)
chromium, and up to 26% is used for harsh environments.
[4] The chromium forms a
passivation layer of
chromium(III) oxide (Cr
2O
3) when exposed to
oxygen. The layer is too thin to be visible, and the metal remains lustrous and smooth. The layer is impervious to
water and air, protecting the metal beneath, and this layer quickly reforms when the surface is scratched. This phenomenon is called
passivation and is seen in other metals, such as
aluminium and
titanium.
Corrosion resistance can 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
nuts and
bolts are forced together, the oxide layer can be scraped off, allowing the parts to
weld together. When forcibly disassembled, the welded material may be torn and pitted, an effect known as
galling.
This destructive galling can be avoided by the use of dissimilar
materials for the parts forced together, for example bronze and
stainless steel, or even different types of stainless steels
(martensitic against austenitic). However, two different alloys
electrically connected in a humid environment may act as a
voltaic pile
and corrode faster. Nitronic alloys made by selective alloying with
manganese and nitrogen may have a reduced tendency to gall.
Additionally, threaded joints may be
lubricated to prevent galling. Low-temperature
carburizing
is another option that virtually eliminates galling and allows the use
of similar materials without the risk of corrosion and the need for
lubrication.
Acids
Stainless steel is generally highly resistant to attack from
acids,
but this quality depends on the kind and concentration of the acid, the
surrounding temperature, and the type of steel. Type 904 is resistant
to
sulfuric acid at room temperature, even in high concentrations; type 316 and 317 are resistant below 10%, and
304 should not be used in the presence of sulfuric acid at any concentration. All types of stainless steel resist attack from
phosphoric acid, 316 and 317 more so than 304; types 304L and 430 have been successfully used with
nitric acid.
Hydrochloric acid will damage any kind of stainless steel, and should be avoided.
[5]
Bases
The 300 series of stainless steel grades is unaffected by any of the weak bases such as
ammonium hydroxide, even in high concentrations and at high temperatures. The same grades of stainless exposed to stronger bases such as
sodium hydroxide
at high concentrations and high temperatures will likely experience
some etching and cracking, especially with solutions containing
chlorides such as
sodium hypochlorite.
[5]
Organics
Types 316 and 317 are both useful for storing and handling
acetic acid, especially in solutions where it is combined with
formic acid
and when aeration is not present (oxygen helps protect stainless steel
under such conditions), though 317 provides the greatest level of
resistance to corrosion. Type 304 is also commonly used with formic acid
though it will tend to discolor the solution. All grades resist damage
from
aldehydes and
amines, though in the latter case grade 316 is preferable to 304;
cellulose acetate will damage 304 unless the temperature is kept low. Fats and
fatty acids
only affect grade 304 at temperatures above 150 °C (302 °F), and grade
316 above 260 °C (500 °F), while 317 is unaffected at all temperatures.
Type 316L is required for processing of
urea.
[5]
Electricity and magnetism
Poor selection of materials can cause
galvanic corrosion to other metals in contact with stainless steel
Like steel, stainless steel is a relatively poor conductor of electricity, with lower
electrical conductivity than copper. Other metals in contact with stainless steel in a damp environment may suffer
galvanic corrosion even though the stainless metal may be unaffected.
Ferritic and
martensitic stainless steels are
magnetic. Annealed
austenitic stainless steels are
non-magnetic.
Work hardening can make austenitic stainless steels slightly magnetic.
3D printing
Some
3D printing providers have developed proprietary stainless steel
sintering blends for use in rapid prototyping. One of the more popular stainless steel grades used in
3D printing
would be 316L stainless steel. Due to the high temperature gradient and
fast rate of solidification, stainless steel manufactured via
3D printing
tends to have more refined microstructures. This in turn results in
better mechanical properties. However, stainless steel is not used as
much as materials like Ti6Al4V in the
3D printing industry. This is because stainless steel manufactured via the traditional methods tends to be more economically competitive.
Types
There are different types of stainless steels: when
nickel is added, for instance, the austenite structure of iron is stabilized. This crystal structure makes such steels virtually non-
magnetic and less
brittle at low temperatures. For greater
hardness and strength, more
carbon is added. With proper
heat treatment, these steels are used for such products as
razor blades, cutlery, and tools.
Significant quantities of
manganese
have been used in many stainless steel compositions. Manganese
preserves an austenitic structure in the steel, similar to nickel, but
at a lower
cost.
Stainless steels are also classified by their
crystalline structure:
- Austenitic, or 200 and 300 series, stainless steels have an austenitic crystalline structure, which is a face-centered cubic
crystal structure. Austenite steels make up 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.
-
- 200 Series—austenitic chromium-nickel-manganese alloys. Type 201 is
hardenable through cold working; Type 202 is a general purpose stainless
steel. Decreasing nickel content and increasing manganese results in
weak corrosion resistance.[6]
-
- 300 Series. The most widely used austenite steel is the 304, also known as 18/8 for its composition of 18% chromium and 8% nickel.[7] 304 may be referred to as A2 stainless (not to be confused with AISI grade A2 air hardening alloy tool steel containing about 5% chromium). The second most common austenite steel is the 316
grade, also referred to as A4 stainless and called marine grade
stainless, used primarily for its increased resistance to corrosion. A
typical composition of 18% chromium and 10% nickel, commonly known as 18/10 stainless, is often used in cutlery and high-quality cookware. 18/0 is also available.
- Superaustenitic stainless steels, such as Allegheny Ludlum alloy AL-6XN and 254SMO, exhibit great resistance to chloride pitting and crevice corrosion because of 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. For example ASTM A387 is
used in pressure vessels but is a low-alloy carbon steel with a chromium
content of 0.5% to 9%.[8] Low-carbon versions, for example 316L or 304L, are used to avoid corrosion problems caused by welding. Grade 316LVM is preferred where biocompatibility is required (such as body implants and piercings).[9] The "L" means that the carbon content of the alloy is below 0.03%, which reduces the sensitization effect (precipitation of chromium carbides at grain boundaries) caused by the high temperatures involved in welding.
- Ferritic
stainless steels generally have better engineering properties than
austenitic grades, but have reduced corrosion resistance, because of the
lower chromium and nickel content. They are also usually less
expensive. Ferritic stainless steels have a body-centered cubic
crystal system and contain between 10.5% and 27% chromium with very
little nickel, if any, but some types can contain lead. Most
compositions include molybdenum; some, aluminium or titanium. Common
ferritic grades include 18Cr-2Mo, 26Cr-1Mo, 29Cr-4Mo, and 29Cr-4Mo-2Ni.
These alloys can be degraded by the presence of
chromium, an intermetallic phase which can precipitate upon welding.
- Martensitic stainless steels are not as corrosion-resistant as the other two classes but are extremely strong and tough, as well as highly machinable,
and can be hardened by heat treatment. Martensitic stainless steel
contains chromium (12–14%), molybdenum (0.2–1%), nickel (less than 2%),
and carbon (about 0.1–1%) (giving it more hardness but making the
material a bit more brittle). It is quenched and magnetic.
- Duplex steel
stainless steels have a mixed microstructure of austenite and ferrite,
the aim usually being to produce a 50/50 mix, although in commercial
alloys the ratio may be 40/60. Duplex stainless steels have roughly
twice the strength compared to austenitic stainless steels and also
improved resistance to localized corrosion, particularly pitting,
crevice corrosion and stress corrosion cracking. They are characterized
by high chromium (19–32%) and molybdenum (up to 5%) and lower nickel
contents than austenitic stainless steels.
- The properties of duplex stainless steels are achieved with an
overall lower alloy content than similar-performing super-austenitic
grades, making their use cost-effective for many applications. Duplex
grades are characterized into groups based on their alloy content and
corrosion resistance.
- Lean duplex refers to grades such as UNS S32101 (LDX 2101), S32202 (UR2202), S32304, and S32003.
- Standard duplex refers to grades with 22% chromium, such as UNS S31803/S32205, with 2205 being the most widely used.
- Super duplex is by definition a duplex stainless steel with a Pitting Resistance Equivalent Number
(PREN) > 40, where PREN = %Cr + 3.3x(%Mo + 0.5x%W) + 16x%N. Usually
super duplex grades have 25% or more chromium. Some common examples are
S32760 (Zeron 100 via Rolled Alloys), S32750 (2507), and S32550 (Ferralium).
- Hyper duplex refers to duplex grades with a PRE > 48. UNS S32707 and S33207 are the only grades currently available on the market.
- 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.
Grades
There are over 150 grades of stainless steel, of which 15 are most commonly used. There are a number of systems for
grading stainless and other steels, including US
SAE steel grades.
Comparison of standardized steels
| 1.4109 |
X65CrMo14 |
440A |
S44002 |
| 1.4112 |
X90CrMoV18 |
440B |
S44003 |
| 1.4125 |
X105CrMo17 |
440C |
S44004 |
|
|
440F |
S44020 |
| 1.4016 |
X6Cr17 |
430 |
S43000 |
| 1.4408 |
G-X 6 CrNiMo 18-10 |
316 |
S31600 |
| 1.4512 |
X6CrTi12 |
409 |
S40900 |
|
|
410 |
S41000 |
| 1.4310 |
X10CrNi18-8 |
301 |
S30100 |
| 1.4318 |
X2CrNiN18-7 |
301LN |
|
| 1.4307 |
X2CrNi18-9 |
304L |
S3043 |
| 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 |
|
| 1.4841 |
X22CrNi2520 |
310 |
S31000 |
| 1.4845 |
X 5 CrNi 2520 |
310S |
S31008[10] |
| 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 |
| 1.4362 |
X2CrNi23-4 |
2304 |
S32304 |
| 1.4462 |
X2CrNiMoN22-5-3 |
2205 |
S31803/S32205 |
| 1.4501 |
X2CrNiMoCuWN25-7-4 |
J405 |
S32760 |
| 1.4539 |
X1NiCrMoCu25-20-5 |
904L |
N08904 |
| 1.4529 |
X1NiCrMoCuN25-20-7 |
|
N08926 |
| 1.4547 |
X1CrNiMoCuN20-18-7 |
254SMO |
S31254 |
Standard finishes
Main article:
Brushed metal
316L stainless steel, with an unpolished, mill finish
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 to change the properties of the final material. Any
oxidation that forms on the surface (
mill scale) is removed by
pickling,
and a 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 condition
- No. 3: Coarse abrasive finish applied mechanically
- No. 4: Brushed finish
- No. 5: Satin finish
- No. 6: Matte finish (brushed but smoother than #4)
- No. 7: Reflective finish
- No. 8: Mirror finish
- No. 9: Bead blast finish
- No. 10: Heat colored finish—offering a wide range of electropolished and heat colored surfaces
Applications
Stainless steel’s resistance to corrosion and staining, low maintenance, and familiar
lustre make it an ideal material for many applications. The alloy is
milled into coils, sheets, plates, bars, wire, and tubing to be used in
cookware,
cutlery,
household hardware,
surgical instruments,
major appliances, industrial equipment (for example, in
sugar refineries)
and as an automotive and aerospace structural alloy and construction
material in large buildings. Storage tanks and tankers used to transport
orange juice
and other food are often made of stainless steel, because of its
corrosion resistance. This also influences its use in commercial
kitchens and food processing plants, as it can be steam-cleaned and
sterilized and does not need paint or other surface finishes.
Stainless steel is used for jewelry and watches, with 316L being the
type commonly used for such applications. It can be re-finished by any
jeweler and will not oxidize or turn black.
Some firearms incorporate stainless steel components as an alternative to
blued or
parkerized steel. Some
handgun models, such as the
Smith & Wesson Model 60 and the Colt
M1911 pistol,
can be made entirely from stainless steel. This gives a high-luster
finish similar in appearance to nickel plating. Unlike plating, the
finish is not subject to flaking, peeling, wear-off from rubbing (as
when repeatedly removed from a holster), or rust when scratched.
Some
automotive manufacturers use stainless steel as decorative highlights in their vehicles.
Architecture
Stainless steel is used for buildings for both practical and aesthetic reasons. Stainless steel was in vogue during the
art deco period. The most famous example of this is the upper portion of the
Chrysler Building
(pictured). Some diners and fast-food restaurants use large ornamental
panels and stainless fixtures and furniture. Because of the durability
of the material, many of these buildings still retain their original
appearance. Stainless steel is used today in building construction
because of its durability and because it is a weldable building metal
that can be made into aesthetically pleasing shapes. An example of a
building in which these properties are exploited is the
Art Gallery of Alberta in
Edmonton, which is wrapped in stainless steel.
Type 316 stainless is used on the exterior of both the
Petronas Twin Towers and the
Jin Mao Building, two of the world's tallest
skyscrapers.
[12]
The
Parliament House of Australia in Canberra has a stainless steel flagpole weighing over 220 tonnes (240 short tons).
The aeration building in the
Edmonton Composting Facility, the size of 14 hockey rinks, is the largest stainless steel building in North America.
Bridges
Monuments and sculptures
- Unisphere, constructed as the theme symbol of the 1964 New York World's Fair, is constructed of Type 304L stainless steel as a spherical framework with a diameter of 120 feet (37 m) (New York City)
- Gateway Arch
(pictured) is clad entirely in stainless steel: 886 tons (804 metric
tonnes) of 0.25 in (6.4 mm) plate, #3 finish, type 304 stainless steel.[14] (St. Louis, Missouri)
- United States Air Force Memorial has an austenitic stainless steel structural skin (Arlington, Virginia)
- Atomium
was renovated with stainless-steel cladding in a renovation completed
in 2006; previously the spheres and tubes of the structure were clad in
aluminium (Brussels, Belgium)
- Cloud Gate sculpture by Anish Kapoor (Chicago, Illinois)
- Sibelius Monument is made entirely of stainless steel tubes (Helsinki, Finland)
- The Kelpies (Falkirk, Scotland)
- Man of Steel (sculpture) under construction (Rotherham, England)
- Juraj Jánošík monument (Terchova, Slovakia)
Other
Surgical tools, such as these
hemostats, are commonly made of stainless steel
Stainless steel is often used for everyday
kitchen sinks, appliances, and cookware
Stainless steel is often used for cookware
Stainless steel is used for industrial equipment when durability and cleanability are important
- Automotive bodies
The
Allegheny Ludlum Corporation worked with
Ford on various
concept cars with stainless steel bodies from the 1930s through the 1970s to demonstrate the material's potential. The 1957 and 1958
Cadillac Eldorado Brougham had a stainless steel roof. In 1981 and 1982, the
DeLorean DMC-12 production automobile used stainless steel body panels over a
glass-reinforced plastic monocoque. Intercity buses made by
Motor Coach Industries are partially made of stainless steel. The aft body panel of the
Porsche Cayman
model (2-door coupe hatchback) is made of stainless steel. It was
discovered during early body prototyping that conventional steel could
not be formed without cracking (due to the many curves and angles in
that automobile). Thus,
Porsche was forced to use stainless steel on the Cayman.
- Passenger rail cars
Rail cars have commonly been manufactured using corrugated stainless
steel panels (for additional structural strength). This was particularly
popular during the 1960s and 1970s, but has since declined. One notable
example was the early
Pioneer Zephyr. Notable former manufacturers of stainless steel rolling stock included the
Budd Company (USA), which has been licensed to Japan's
Tokyu Car Corporation, and the Portuguese company
Sorefame. Many railcars in the United States are still manufactured with stainless steel, unlike other countries who have shifted away.
- Aircraft
Budd also built an airplane, the
Budd BB-1 Pioneer, of stainless steel tube and sheet, which is on display at the
Franklin Institute.
The American
Fleetwings Sea Bird amphibious aircraft of 1936 was also built using a spot-welded stainless steel hull.
The Bristol Aeroplane Company built the all-stainless steel
Bristol 188 high-speed research aircraft, which first flew in 1963.
The use of stainless steel in mainstream aircraft is hindered by its excessive weight compared to other materials, such as
aluminum.
- Airports
Stainless steel is a modern trend for roofing material for airports
due to its low glare reflectance to keep pilots from being blinded, also
for its properties that allow thermal reflectance in order to keep the
surface of the roof close to ambient temperature. The
Hamad International Airport in
Qatar was built with all stainless steel roofing for these reasons, as well as the
Sacramento International Airport in
California.
- Jewelry
Valadium, a stainless steel and 12% nickel alloy is used to make
class and military rings. Valadium is usually silver-toned, but can be
electro-plated to give it a gold tone. The gold tone variety is known as
Sun-lite Valadium.
[15] Other "Valadium" types of alloy are trade-named differently, with such names as "Siladium" and "White Lazon."
- Surgery and dentistry
Surgical tools and medical equipment are usually made of stainless
steel, because of its durability and ability to be sterilized in an
autoclave. In addition,
surgical implants
such as bone reinforcements and replacements (e.g. hip sockets and
cranial plates) are made with special alloys formulated to resist
corrosion, mechanical wear, and biological reactions
in vivo.
Stainless steel is used in a variety of applications in dentistry. It
is common to use stainless steel in many instruments that need to be
sterilized, such as needles,
[16] endodontic files in
root canal therapy, metal posts in root canal–treated teeth, temporary crowns and crowns for
deciduous teeth, and arch wires and brackets in orthodontics.
[17] The surgical stainless steel alloys (e.g., 316 low-carbon steel) have also been used in some of the early dental implants.
[18]
- Kitchens
Stainless steel is often preferred for
kitchen sinks because of its ruggedness, durability, heat resistance, and ease of cleaning. In better models,
acoustic noise is controlled by applying
resilient undercoating to dampen vibrations. The material is also used for cladding of surfaces such as
appliances and
backsplashes.
Cookware and bakeware
may be clad in stainless steels, to enhance their cleanability and
durability. Because stainless steel is a poor conductor of heat, it is
often used as a thin surface cladding over a core of copper or aluminum,
which conduct heat more readily.
Maintenance
If treated or stored incorrectly, any grade of stainless steel may
discolor or stain. To maintain optimum appearance, the surface should be
cared for regularly.
During installation
The quality of installation affects the durability and lifespan of stainless steel.
[19]
Therefore, it is important to make sure stainless steel is in good
condition before installation. Normally, giving it a quick clean is
enough prior to installation. However, if surface contamination is
present, more attention is required. In fields such as aerospace,
pharmaceuticals and food handling, an extremely high standard of
cleanliness may be required, so extra care should be taken.
Routine maintenance
Maintenance is required to maintain the quality and appearance of
steel. Depending on the environment, it is carried out between one and
ten times per year. A proper maintenance routine significantly prolongs
the life of stainless steel.
[20]
Maintenance tools
Abrasive cleaning tools should be avoided to prevent alteration of
stainless steel finishes. Chloride-containing solutions, such as bleach,
should also be avoided.
- Soft cloth and water: suitable for cosmetic issues and general cleaning
- Mild detergent: needed if stains cannot be easily lifted with water
- Glass cleaner: useful for removing fingerprints and similar stains
Despite its design and use, stainless steel can still be susceptible
to corrosion, some grades more than others, and especially in corrosive
environments. Challenging environments include saline environments, such
as coastal areas where regular exposure to sea salt is common and
northern urban areas where de-icing salts are common during winter.
Manufacturing environments, especially in chemical and food industries,
may also be subject to corrosive substances.
Stainless steel may also corrode if surfaces come into direct contact
with iron or carbon steel. Trace particles from iron or carbon steel
will rust on stainless steel surfaces. If left unattended, rust spots
may compromise surface passivation and may spread internally.
Contamination is common when stainless steel is subject to sparks from
nearby welding, cutting, drilling, or grinding of carbon steel.
Treating stainless steel corrosion[23][24]
- Light rust: all-purpose lubricant or domestic stainless steel cleaners (typically containing calcium carbonate or citric acid)
- Moderate rust: phosphorus acid solutions
- Severe rust: hydrofluoric acid bath (typically performed by
professional service providers due to the hazardous nature of chemicals)
Recycling and reuse
Stainless steel is 100%
recyclable.
An average stainless steel object is composed of about 60% recycled
material of which approximately 40% originates from end-of-life products
and about 60% comes from manufacturing processes.
[25] According to the
International Resource Panel's
Metal Stocks in Society report,
the per capita stock of stainless steel in use in society is 80–180 kg
in more developed countries and 15 kg in less-developed countries.
There is a secondary market that recycles usable scrap for many
stainless steel markets. The product is mostly coil, sheet, and blanks.
This material is purchased at a less-than-prime price and sold to
commercial quality stampers and sheet metal houses. The material may
have scratches, pits, and dents but is made to the current
specifications.
Health effects
Stainless steel is generally considered to be biologically inert, but
some sensitive individuals develop a skin irritation due to a
nickel allergy caused by certain alloys.
History
An announcement, as it appeared in the 1915
New York Times, of the development of stainless steel
[26]
The corrosion resistance of iron-chromium alloys was first recognized in 1821 by
French metallurgist
Pierre Berthier, who noted their resistance against attack by some acids and suggested their use in
cutlery.
Metallurgists of the 19th century 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 1872, the Englishmen Clark and Woods patented an alloy that would today be considered a stainless steel.
[27]
In the late 1890s
Hans Goldschmidt of
Germany developed an aluminothermic (
thermite) process for producing carbon-free chromium. Between 1904 and 1911 several researchers, particularly
Leon Guillet of France, prepared alloys that would today be considered stainless steel.
[28]
Friedrich Krupp Germaniawerft built the 366-ton sailing yacht
Germania featuring a chrome-nickel steel hull in Germany in 1908.
[29] In 1911,
Philip Monnartz reported on the relationship between chromium content and corrosion resistance. On 17 October 1912,
Krupp engineers Benno Strauss and Eduard Maurer patented
austenitic stainless steel as
Nirosta.
[30][31][32]
Similar developments were taking place contemporaneously in the
United States, where Christian Dantsizen and Frederick Becket were
industrializing
ferritic stainless steel. In 1912,
Elwood Haynes applied for a US patent on a
martensitic stainless steel alloy, which was not granted until 1919.
[33]
Also in 1912,
Harry Brearley of the
Brown-Firth research laboratory in
Sheffield, England,
while seeking a corrosion-resistant alloy for gun barrels, discovered
and subsequently industrialized a martensitic stainless steel alloy. The
discovery was announced two years later in a January 1915 newspaper
article in
The New York Times.
[26] The metal was later marketed under the "Staybrite" brand by
Firth Vickers in England and was used for the new entrance canopy for the
Savoy Hotel in
London in 1929.
[34]
Brearley applied for a US patent during 1915 only to find that Haynes
had already registered a patent. Brearley and Haynes pooled their
funding and with a group of investors formed the American Stainless
Steel Corporation, with headquarters in Pittsburgh, Pennsylvania.
[35]
In the beginning stainless steel was sold in the US under different brand names like "
Allegheny metal"
and "Nirosta steel". Even within the metallurgy industry the eventual
name remained unsettled; in 1921 one trade journal was calling it
"unstainable steel."
[36] In 1929, before the Great Depression hit, over 25,000 tons of stainless steel were manufactured and sold in the US.
[37]
See also
References
Stainless steel cladding is used on the Walt Disney Concert Hall
Stainless steel does not readily corrode, rust or stain with water as ordinary steel does. However, it is not fully stain-proof in low-oxygen, high-salinity, or poor air-circulation environments.[2] There are different grades and surface finishes of stainless steel to suit the environment the alloy must endure. Stainless steel is used where both the properties of steel and corrosion resistance are required.Stainless steel is used for corrosion-resistant tools such as this nutcracker
Stainless steel (row 3) resists salt-water corrosion better than aluminum-bronze (row 1) or copper-nickel alloys (row 2)
Stainless steel is not completely immune to corrosion in this desalination equipment
Like steel, stainless steel is a relatively poor conductor of electricity, with lower electrical conductivity than copper. Other metals in contact with stainless steel in a damp environment may suffer galvanic corrosion even though the stainless metal may be unaffected.Poor selection of materials can cause galvanic corrosion to other metals in contact with stainless steel
Swiss Army knives are made of martensitic stainless steel.
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 to change the properties of the final material. Any oxidation that forms on the surface (mill scale) is removed by pickling, and a passivation layer is created on the surface. A final finish can then be applied to achieve the desired aesthetic appearance.316L stainless steel, with an unpolished, mill finish
The 630-foot-high (190 m), stainless-clad (type 304) Gateway Arch defines St. Louis's skyline
The pinnacle of New York's Chrysler Building is clad with Nirosta stainless steel, a form of Type 302[11][12]
Stainless steel’s resistance to corrosion and staining, low maintenance, and familiar lustre make it an ideal material for many applications. The alloy is milled into coils, sheets, plates, bars, wire, and tubing to be used in cookware, cutlery, household hardware, surgical instruments, major appliances, industrial equipment (for example, in sugar refineries) and as an automotive and aerospace structural alloy and construction material in large buildings. Storage tanks and tankers used to transport orange juice and other food are often made of stainless steel, because of its corrosion resistance. This also influences its use in commercial kitchens and food processing plants, as it can be steam-cleaned and sterilized and does not need paint or other surface finishes.An art deco sculpture on the Niagara-Mohawk Power building in Syracuse, New York
Surgical tools, such as these hemostats, are commonly made of stainless steel
Stainless steel is often used for everyday kitchen sinks, appliances, and cookware
Stainless steel is often used for cookware
Stainless steel is used for industrial equipment when durability and cleanability are important
The corrosion resistance of iron-chromium alloys was first recognized in 1821 by French metallurgist Pierre Berthier, who noted their resistance against attack by some acids and suggested their use in cutlery. Metallurgists of the 19th century 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.An announcement, as it appeared in the 1915 New York Times, of the development of stainless steel[26]
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