Category: Stainless steels

05.12.2020 By Vulkree

Stainless steels

Stainless steel's resistance to ferric oxide formation results from the presence of chromium in the alloy, which forms a passive film that protects the underlying material from corrosion attack, and can self-heal in the presence of oxygen. The addition of nitrogen also improves resistance to pitting corrosion and increases mechanical strength. Resistance to corrosion and staining, low maintenance, and familiar luster make stainless steel an ideal material for many applications where both the strength of steel and corrosion resistance are required.

Moreover, stainless steel can be rolled into sheetsplates, bars, wire, and tubing. These can be used in cookwarecutlerysurgical instrumentsmajor appliancesconstruction material in large buildings, industrial equipment e. The material's corrosion resistance, the ease with which it can be steam-cleaned and sterilized, and the absence of the need for surface coatings have prompted the use of stainless steel in kitchens and food processing plants.

The invention of stainless steel followed a series of scientific developments, starting in when chromium was first shown to the French Academy by Louis Vauquelin. In the early s, James Stodart, Michael Faradayand Robert Mallet observed the resistance of chromium-iron alloys "chromium steels" to oxidizing agents.

Robert Bunsen discovered chromium's resistance to strong acids. The corrosion resistance of iron-chromium alloys may have been first recognized in by Pierre Berthierwho noted their resistance against attack by some acids and suggested their use in cutlery. In the s, both Sheffield steelmakers and Krupp were producing chromium steel with the latter employing it for cannons in the s.

These events led to the first production of chromium-containing steel by J. Baur of the Chrome Steel Works of Brooklyn for the construction of bridges. Patent for the product was issued in They pursued the commercial value of the innovation via a British patent for "Weather-Resistant Alloys".

In the late s, German chemist Hans Goldschmidt developed an aluminothermic thermite process for producing carbon-free chromium. Between andseveral researchers, particularly Leon Guillet of France, prepared alloys that would be considered stainless steel today. InFriedrich Krupp Germaniawerft built the ton sailing yacht Germania featuring a chrome-nickel steel hull in Germany.

InPhilip Monnartz reported on the relationship between chromium content and corrosion resistance. Similar developments were taking place in the United States, where Christian Dantsizen and Frederick Becket were industrializing ferritic stainless steel. InElwood Haynes applied for a US patent on a martensitic stainless steel alloy, which was not granted until While seeking a corrosion-resistant alloy for gun barrels inHarry Brearley of the Brown-Firth research laboratory in Sheffield, England, discovered and subsequently industrialized a martensitic stainless steel alloy.

The discovery was announced two years later in a January newspaper article in The New York Times. 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 Stainless steelany one of a family of alloy steels usually containing 10 to 30 percent chromium. In conjunction with low carbon content, chromium imparts remarkable resistance to corrosion and heat. Other elements, such as nickelmolybdenumtitaniumaluminumniobiumcoppernitrogensulfurphosphorusor seleniummay be added to increase corrosion resistance to specific environmentsenhance oxidation resistance, and impart special characteristics.

Most stainless steels are first melted in electric-arc or basic oxygen furnaces and subsequently refined in another steelmaking vessel, mainly to lower the carbon content. In the argon-oxygen decarburization process, a mixture of oxygen and argon gas is injected into the liquid steel. By varying the ratio of oxygen and argon, it is possible to remove carbon to controlled levels by oxidizing it to carbon monoxide without also oxidizing and losing expensive chromium.

Thus, cheaper raw materials, such as high-carbon ferrochromiummay be used in the initial melting operation. There are more than grades of stainless steel. The majority are classified into five major groups in the family of stainless steels: austenitic, ferritic, martensitic, duplex, and precipitation-hardening.

Austenitic steelswhich contain 16 to 26 percent chromium and up to 35 percent nickel, usually have the highest corrosion resistance. They are not hardenable by heat treatment and are nonmagnetic. Typical applications include aircraft and the dairy and food-processing industries. Standard ferritic steels contain Martensitic steels typically contain They are hardenable by heat treatment, have modest corrosion resistance, and are employed in cutlerysurgical instruments, wrenchesand turbines.

Duplex stainless steels are a combination of austenitic and ferritic stainless steels in equal amounts; they contain 21 to 27 percent chromium, 1. Duplex stainless steels are stronger and more resistant to corrosion than austenitic and ferritic stainless steels, which makes them useful in storage-tank construction, chemical processing, and containers for transporting chemicals.

Precipitation-hardening stainless steel is characterized by its strength, which stems from the addition of aluminum, copper, and niobium to the alloy in amounts less than 0. It is comparable to austenitic stainless steel with respect to its corrosion resistance, and it contains 15 to Precipitation-hardening stainless steel is used in the construction of long shafts. Stainless steel.

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Stainless steel

Thank you for your feedback. Home Technology Industry. The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree See Article History. Read More on This Topic. This outstanding group receives its stainless characteristics from an invisible, self-healing chromium oxide film that forms when chromium Learn More in these related Britannica articles:.

This outstanding group receives its stainless characteristics from an invisible, self-healing chromium oxide film that forms when chromium is added at concentrations greater than More than two thirds of global nickel production is used to produce stainless steel. As an alloying element, nickel enhances its important properties such as formability, weldability and ductility, while increasing corrosion resistance in certain applications. Stainless steel has been in use for more than one hundred years.

It comprises a wide range of iron-based alloys, but unlike conventional steel they are resistant to corrosion and do not rust when exposed to water alone. In addition to their inherent corrosion resistance, nickel-containing stainless steels are easy to form and weld; they remain ductile at very low temperatures and yet can be used for high-temperature applications. In addition, unlike conventional steel and non-nickel-containing stainless steel, they are non-magnetic. This means they can be made into an exceptionally wide range of products, spanning applications in the chemical industry, the health sector and domestic uses.

Nickel provides these properties by changing the crystal structure of steel to an austenitic face-centred cubic crystal structure at almost all temperatures.

Conventional steel has a ferritic body-centred cubic crystal structure at ambient temperature. The austenitic structure provides stainless steels with good ductility and formability. A slightly higher nickel content further increases the stability of the austenite and reduces the work-hardening tendency, increasing suitability for deep drawing. Unlike low-nickel, high-manganese alloys, these alloys are not prone to delayed cold cracking.

Their excellent formability has led to series austenitic alloys being widely used for items such as kitchen sinks and cooking pots. Many pieces of stainless steel equipment are fabricated by welding. In general, nickel austenitic alloys are better for welding than other alloys, with Types and being the most widely-fabricated stainless steels in the world. Unlike ferritic alloys, they are not prone to brittleness as a result of high-temperature grain growth and the welds have excellent bend and impact properties.

They are readily weldable in both thick and thin sections.

Type 316 and 316L Stainless Steels

Toughness - the ability of a material to absorb energy without breaking - is essential in many engineering applications. Most stainless steels have good toughness at room temperature, however, as temperature decreases the ferritic structure becomes progressively more brittle, making ferritic stainless steels unsuitable for use at cryogenic temperatures. In contrast, the common austenitic stainless steels retain good toughness even at liquid helium temperatures oCwhich is why grades such as Type are widely used for cryogenic applications.

stainless steels

Adding nickel gives the austenitic alloys of stainless steel significantly greater high-temperature strength than other alloys, particularly the ability to resist the tendency to move slowly or deform permanently under mechanical stresses, known as creep.

These alloys are also much less prone to forming damaging brittle phases when exposed to temperatures in excess of oC. Nickel also stabilises the protective oxide film and reduces spalling during thermal cycling.

This is why austenitic alloys are preferred for high-temperature applications and where fire resistance is needed. This, in turn, lessens the environmental impact of nickel-containing stainless steels by reducing both the need for virgin materials and the energy that their production uses. The durability of stainless steels can be seen in buildings.

Ease of production is not something that is immediately apparent to the end user. However, long experience of manufacturing the common austenitic alloys, their widespread use, their versatility and the scale of their production have allowed them to become widely and economically available in all shapes and quantities and in all parts of the world.

The common nickel-containing austenitic alloys are clearly excellent all-round performers.

The difference between 304 and 316 stainless steels

They are widely available, their properties and applications are well-understood and they are versatile and easy to use. They also demonstrate excellent durability and are extensively recycled when their useful life is over. They frequently offer the most practical, lowest-risk material choice, meaning these grades are found in a wide range of applications:. It is the addition of nickel that enables stainless steel to become such a versatile alloy.

Ferritic cube. Austenistic cube. The properties of nickel-containing stainless steel. Formability The austenitic structure provides stainless steels with good ductility and formability.Marine-grade stainless steel, called typeis resistant to certain types of corrosive environments. Some common types are the L, F, N, and H variants. Each is slightly different, and each is used for different purposes. The "L" designation means L steel has less carbon than This is easy to remember, as the L stands for "low.

Cost is very similar, and both are durable, corrosion-resistant, and a good choice for high-stress situations. However, can be annealed to resist weld decay. And neither are as durable as and L, which have higher molybdenum content and are better for overall corrosion resistance.

The molybdenum content increases corrosion resistance, improves resistance to pitting in chloride ion solutions, and increases strength at high temperatures. Type grade stainless steel is particularly effective in acidic environments. This grade of steel is effective in protecting against corrosion caused by sulfuric, hydrochloric, acetic, formic, and tartaric acids, as well as acid sulfates and alkaline chlorides. Common uses for type stainless steel include in the construction of exhaust manifolds, furnace parts, heat exchangers, jet engine parts, pharmaceutical and photographic equipment, valve and pump parts, chemical processing equipment, tanks, and evaporators.

It also is used in pulp, paper, and textile processing equipment and for any parts exposed to marine environments. The lower carbon content in L minimizes deleterious carbide precipitation carbon is drawn out of the metal and reacts with chromium due to heat, weakening the corrosion resistance as a result of welding.

Consequently, L is used when welding is required to ensure maximum corrosion resistance. Share Flipboard Email. Terence Bell.

Terence Bell wrote about commodities investing for The Balance, and has over 10 years experience in the rare earth and minor metal industries. Updated March 02, Physical Properties of type and L steels:.

Density: 0.

stainless steels

Manganese 2. Phosphorus 0. Sulfur 0. Silicon 0. Chromium Iron Balance Balance.Highly ductile, for formed products. Also hardens rapidly during mechanical working.

Good weldability. Better wear resistance and fatigue strength than Easier machining version of via addition of sulfur and phosphorus. The second most common grade after ; for food and surgical stainless steel uses; Alloy addition of molybdenum prevents specific forms of corrosion.

Also known as "marine grade" stainless steel due to its increased resistance to chloride corrosion compared to type SS is often used for building nuclear reprocessing plants. Most watches that are made of stainless steel are made of this grade. Rolex is an exception in that they use Type L. Similar to but lower risk of weld decay due to addition of titanium.

Stainless steel

See also with addition of niobium for desensitization during welding. Also known as "surgical steel". Excellent polishability. Good formability, but with reduced temperature and corrosion resistance.

It can be hardened to Rockwell 58 hardness, making it one of the hardest stainless steels. Also known as "razor blade steel". Available in three grades A, B, C more common and F free machinable. Do you want to learn more about: Making your material search easier Reducing your lead times Eliminating frustrating searches with multiple suppliers. Same corrosion resistance aswith slightly higher strength due to additional carbon.

Wear resistant, but less corrosion resistant. Do you want to learn more about: Making your material search easier Reducing your lead times Eliminating frustrating searches with multiple suppliers Sign up for Continental Steel product highlights and deals:.After heat treating, precipitation hardening stainless steels develop a high strength-to-weight ratio making it an ideal material for high-end applications such as aerospace and petrochemical.

Precipitation Hardening PH stainless steels are classified as martensitic or semi-austenitic. They develop their high strength and hardness through a variety of heat treatments resulting in a very high strength-to-weight ratio. They are austenitic in the annealed state, and martensitic in the hardened condition. The PH grades achieve high tensile properties in heat treated conditions. Applications for PH steels include aerospace components, flat springs, and retaining rings. Corrosion resistance of precipitation hardening stainless steels is generally superior to that of the standard hardenable martensitic stainless steels, but is not quite as good as chromium-nickel Type Corrosion resistance of the PH stainless steels depends, to some extent, on the heat treated condition.

Accelerated laboratory corrosion tests have been conducted on the precipitation hardening stainless steels since their development, as well as extensive in-service use in a variety of corrosive conditions. The semi-austenitic precipitation hardening stainless steels in Condition A can be readily formed prior to heat treatment.

Work hardening and springback in these steels is similar to that of Type Semi-austenitic PH stainless steels in Condition C and the martensitic PH stainless steels are extremely hard and strong and as such are limited to mild forming operations. Standard heat treatments have been developed to achieve a variety of strength levels in the PH stainless steels. The semi-austenitic PH grades require a multi-step heat treatment to achieve their full strength potential. The precipitation hardening class of stainless steels is generally considered to be weldable by common fusion and resistance techniques.

Special consideration is required to achieve optimum mechanical properties by considering the best heat-treated conditions in which to weld and which heat treatments should follow welding. Skip to main content.

stainless steels

Our Products. Precipitation Hardening Stainless Steels. Contact Our Sales Team We're here to answer your questions. Available Grades. Product Details. Corrosion Resistance. Heat Treatment. Stainless Steel Stainless Steel Comparator pdf.

stainless steels

Contact Us. Request Information Our team or one of our subsidiaries will be in touch promptly to address your inquiry. Carbon Steel. Stainless Steel. Electrical Steel.Alloying metallic elements added during the making of the steel increase corrosion resistance, hardness, or strength. The metals used most commonly as alloying elements in stainless steel include chromium, nickel, and molybdenum.

Stainless steels are a iron-based alloy containing at between Stainless steel achieve its stainless characteristic through the formation of an invisible and adherent chromium-rich oxide surface film. Other alloying elements added to improve the characteristics of the stainless steel include nickel, molybdenum, copper, titanium, aluminum, silicon, niobium, nitrogen, sulphur, and selenium.

Since stainless steel resists corrosion, maintains its strength at high temperatures, and is easily maintained, it is widely used in items such as automotive and food processing products, as well as medical and health equipment. The most common US grades of stainless steel are:.

The most commonly specified austenitic chromium-nickel stainless class stainless steel, accounting for more than half of the stainless steel produced in the world. This grade withstands ordinary corrosion in architecture, is durable in typical food processing environments, and resists most chemicals. Type is available in virtually all product forms and finishes.

The inclusion of molybdenum gives greater resistance to various forms of deterioration. Ferritic plain chromium stainless category stainless steel suitable for high temperatures. This grade has the lowest chromium content of all stainless steels and thus is the least expensive. The most widely used martensitic plain chromium stainless class with exceptional strength stainless steel, featuring the high level of strength conferred by the martensitics. It is a low-cost, heat-treatable grade suitable for non-severe corrosion applications.

The most widely used ferritic plain chromium stainless category stainless steel, offering general-purpose corrosion resistance, often in decorative applications. Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro.

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AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information. If you want to promote your products or services in the Engineering ToolBox - please use Google Adwords. Stainless Steels Classifications Stainless steels are commonly grouped into martensitic stainless steels, ferritic stainless steels, austenitic stainless steels, duplex ferritic-austenitic stainless steels, and precipitation-hardening stainless steels Sponsored Links.

Stainless steels are in general grouped into martensitic stainless steels ferritic stainless steels austenitic stainless steels duplex ferritic-austenitic stainless steels precipitation-hardening stainless steels Alloying metallic elements added during the making of the steel increase corrosion resistance, hardness, or strength.

Stainless steels are available in the form of plate sheet strip foil bar wire pipes tubes Stainless steels are a iron-based alloy containing at between Carbon is normally in amounts from 0.