What is cast iron made of?
Cast iron
Cast iron is made from pig iron, which is the product of smelting iron ore in a blast furnace. Cast iron can be made directly from the molten pig iron or by re-melting pig iron, often along with substantial quantities of iron, steel, limestone, carbon (coke) and taking various steps to remove undesirable contaminants. Phosphorus and sulfur may be burnt out of the molten iron, but this also burns out the carbon, which must be replaced. Depending on the application, carbon and silicon content are adjusted to the desired levels, which may be anywhere from 2–3.5% and 1–3%, respectively. If desired, other elements are then added to the melt before the final form is produced by casting.
Medieval technology
Cast iron had been made in China before the 4th century BC. European cast iron first appears in Middle Europe (for instance Lapphyttan in Sweden, Dürstel in Switzerland and the Märkische Sauerland in Germany) around 1150, in some places according to recent research even before 1100. The technique is considered to be an independent European development.
Cast iron pipe
Cast iron proved to be a beneficial material for the manufacture of water pipes and was used as a replacement for the original elm pipelines utilized earlier. These water pipelines were composed of individually cast pipe sections, often termed sticks, jointed together by a bell and spigot joint. Here one end of the pipe stick is flared, termed the bell or socket, to enable the opposite end of the next stick, the spigot end, to be inserted to create a joint. The gaps in these joints were sealed with oakum to prevents the water leaking out. A molten-lead joint was then run around the socket to ensure that the oakum seal remained in place.
Cannon
Field artillery cannon in Europe and the Americas were initially made most often of bronze, though later forms were constructed of cast iron and eventually steel. Bronze has several characteristics that made it preferable as a construction material: although it is relatively expensive, does not always alloy well, and can result in a final product that is "spongy about the bore", bronze is more flexible than iron and therefore less prone to bursting when exposed to high pressure; cast iron cannon are less expensive and more durable generally than bronze and withstand being fired more times without deteriorating. However, cast iron cannon have a tendency to burst without having shown any previous weakness or wear, and this makes them more dangerous to operate.
Cast iron pipe
The first cast iron pipe was produced in horizontal moulds, the core of the mould would be supported on small iron rods which would become part of the pipe. Horizontal casting resulted in an uneven distribution of metal around the pipe circumference. Typically slag would collect at the crown of the pipe creating a much weaker section.
Cast iron
Cast iron tends to be brittle, except for malleable cast irons. With its relatively low melting point, good fluidity, castability, excellent machinability, resistance to deformation and wear resistance, cast irons have become an engineering material with a wide range of applications and are used in pipes, machines and automotive industry parts, such as cylinder heads (declining usage), cylinder blocks and gearbox cases (also declining usage). It is resistant to destruction and weakening by oxidation.
Cast iron
Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its colour when fractured: white cast iron has carbide impurities which allow cracks to pass straight through, grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks, and ductile cast iron has spherical graphite "nodules" which stop the crack from further progressing.
Cookware and bakeware
Enameled cast iron cooking vessels are made of cast iron covered with a porcelain surface. This creates a piece that has the heat distribution and retention properties of cast iron combined with a non-reactive, low-stick surface.
The enamel over steel technique creates a piece that has the heat distribution of carbon steel and a non-reactive, low-stick surface. Such pots are much lighter than most other pots of similar size, are cheaper to make than stainless steel pots, and do not have the rust and reactivity issues of cast iron or carbon steel. Enamel over steel is ideal for large stockpots and for other large pans used mostly for water-based cooking. Because of its light weight and easy cleanup, enamel over steel is also popular for cookware used while camping.
Cladding is a technique for fabricating pans with a layer of efficient heat conducting material, such as copper or aluminum, covered on the cooking surface by a non-reactive material such as stainless steel, and often covered on the exterior aspect of the pan ("dual-clad") as well. Some pans feature a copper or aluminum interface layer that extends over the entire pan rather than just a heat-distributing disk on the base. Generally, the thicker the interface layer, especially in the base of the pan, the more improved the heat distribution. Claims of thermal efficiency improvements are, however, controversial, owing in particular to the limiting and heat-banking effect of stainless steel on thermal flows.
Cast iron
During the Industrial Revolution, cast iron was also widely used for frame and other fixed parts of machinery, including spinning and later weaving machines in textile mills. Cast iron became widely used, and many towns had foundries producing industrial and agricultural machinery.
Cast stone
Cast stone has been a prime building material for hundreds of years. The earliest known use of cast stone dates from about 1138 in the fortress of Carcassonne, France. Cast stone was first used extensively in London in the 19th century and gained widespread acceptance in America in 1920.
Cast-iron cookware
The Lodge Manufacturing company is currently the only major manufacturer of cast-iron cookware in the United States, as most other cookware suppliers use pots and pans made in Asia or Europe.
Surface plate
Prior to World War II, almost all surface plates were made from ribbed cast iron with the ribbing used to increase stiffness without incurring the weight of solid construction. The cast iron was aged to reduce stress in the metal in an effort to decrease the likelihood of the plate twisting or warping over time.
Richmond, Virginia
Among Richmond's most interesting architectural features is its Cast-iron architecture. Second only to New Orleans in its concentration of cast iron work, the city is home to a unique collection of cast iron porches, balconies, fences, and finials. Richmond's position as a center of iron production helped to fuel its popularity within the city. At the height of production in the 1890, 25 foundries operated in the city employing nearly 3,500 metal workers. This number is seven times the number of general construction workers being employed in Richmond at the time which illustrates the importance of its iron exports. Porches and fences in urban neighborhoods such as Jackson Ward, Church Hill, and Monroe Ward are particularly elaborate, often featuring ornate iron casts never replicated outside of Richmond. In some cases cast were made for a single residential or commercial application.
Surface plate
Despite a fall in popularity among machine shops, cast iron remains the most popular material for surface masters (different usage from a surface plate) among laboratory metrologists, machine builders, gauge makers, and other high-accuracy industries that have a requirement for gauging flatness. Cast iron that has been properly cast is more dimensionally and geometrically stable over time than granite or ceramics, is more easily worked to a higher grade of flatness, and provides a better bearing surface to assist the creation of other master standards. These specialized surface plates are produced in sets of three, by the company that will be using them, so the plates may be regularly verified and refined without the need to send the plates out for external rework. Despite the very stable structure, cast iron remains unsuitable even in high tolerance production applications for use as a normal surface plate because of thermal expansion encountered with regular use as an inspection tool. The nature and use of a surface master, by contrast, already necessitates expensive measures to control temperature regardless of material choice, and cast iron becomes preferable.
Industrial Revolution
Bar iron was the commodity form of iron used as the raw material for making hardware goods such as nails, wire, hinges, horse shoes, wagon tires, chains, etc. and for structural shapes. A small amount of bar iron was converted into steel. Cast iron was used for pots, stoves and other items where its brittleness was tolerable. Most cast iron was refined and converted to bar iron, with substantial losses. Bar iron was also made by the bloomery process, which was the predominant iron smelting process until the late 18th century.
Materials science
The study of metal alloys is a significant part of materials science. Of all the metallic alloys in use today, the alloys of iron (steel, stainless steel, cast iron, tool steel, alloy steels) make up the largest proportion both by quantity and commercial value. Iron alloyed with various proportions of carbon gives low, mid and high carbon steels. An iron-carbon alloy is only considered steel if the carbon level is between 0.01% and 2.00%. For the steels, the hardness and tensile strength of the steel is related to the amount of carbon present, with increasing carbon levels also leading to lower ductility and toughness. Heat treatment processes such as quenching and tempering can significantly change these properties, however. Cast Iron is defined as an iron–carbon alloy with more than 2.00% but less than 6.67% carbon. Stainless steel is defined as a regular steel alloy with greater than 10% by weight alloying content of Chromium. Nickel and Molybdenum are typically also found in stainless steels.
Cast iron pipe
The oldest cast iron water pipes date from the 17th century and were installed to distribute water throughout the gardens of the Chateau de Versailles. These amount to some 35 km of pipe, typically 1m lengths with flanged joints. The extreme age of these pipes make them of considerable historical value. Despite extensive refurbishment in 2008 by Saint-Gobain PAM, 80% remain original.
Cast-iron cookware
The primary producers of traditional cast iron in France are Le Creuset and Staub, though both companies only offer enameled cast iron cookware lines. Netherton Foundry in Shropshire, England, produces cast iron and spun iron cookware. Skeppshult is a Scandinavian foundry that produces cast iron cookware and cast iron kitchen accessories. While there are many well-established brands in the United States such as Milo, Camp Chef, Lodge, Bayou Classic, and John Wright, most manufacture their cookware in China.
Cementite
Cementite (or iron carbide) is a compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula FeC. By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. It is a hard, brittle material, normally classified as a ceramic in its pure form, and is a frequently found and important constituent in ferrous metallurgy. While cementite is present in most steels and cast irons, it is produced as a raw material in the iron carbide process, which belongs to the family of alternative ironmaking technologies.
Architectural metals
Cast iron was a major 19th century building material of the Industrial Revolution. Although brittle, it is remarkably strong in compression. It was frequently used for structural purposes, such as columns, building fronts, domes and light courts. Decorative uses have included stairs, elevators, lintels, grilles, verandas, balconies, railings, fences, streetlights, and tombs. The Bradbury Building is an example of extensive decorative cast iron. Today, cast iron is used for plumbing fixtures and piping in new construction, and its structural and decorative use is used occasionally through historic preservation practices.
Wrought iron
Wrought iron lacks the carbon content necessary for hardening through heat treatment, but in areas where steel was uncommon or unknown, tools were sometimes cold-worked (hence cold iron) in order to harden them. An advantage of its low carbon content is its excellent weldability. Furthermore, sheet wrought iron cannot bend as much as steel sheet metal (when cold worked). Wrought iron can be melted and cast, however the product is no longer wrought iron, since the slag stringers characteristic of wrought iron disappear on melting, so the product resembles impure cast Bessemer steel. There is no engineering advantage as compared to cast iron or steel, both of which are cheaper.
Ferrous metallurgy
Cast iron is rather brittle and unsuitable for striking implements. It can, however, be "decarburized" to steel or wrought iron by heating it in air for several days. In China, these iron working methods spread northward, and by 300 BC, iron was the material of choice throughout China for most tools and weapons. A mass grave in Hebei province, dated to the early 3rd century BC, contains several soldiers buried with their weapons and other equipment. The artifacts recovered from this grave are variously made of wrought iron, cast iron, malleabilized cast iron, and quench-hardened steel, with only a few, probably ornamental, bronze weapons.
James Bogardus
Bogardus attached plaques to his cast-ironwork that read: "James Bogardus Originator & Patentee of Iron Buildings Pat' May 7, 1850." After his invention of cast-iron in the early 1850s, he demonstrated the use of it in the construction of building facades, especially in New York City for the next two decades. He was based in New York, but also worked in Washington, DC, where three cast-iron structures erected by Bogardus in 1851 were the first such constructions in the capital. The success of the cast-iron exteriors from 1850-1880 led to the adoption of steel-frame construction for entire buildings.
Ferrous metallurgy
Steel (with a carbon content between pig iron and wrought iron) was first produced in antiquity as an alloy. Its process of production, Wootz steel, was exported before the 4th century BC from India to ancient China, Africa, the Middle East and Europe. Archaeological evidence of cast iron appears in 5th-century BC China. New methods of producing it by carburizing bars of iron in the cementation process were devised in the 17th century. During the Industrial Revolution, new methods of producing bar iron by substituting coke for charcoal were devised and these were later applied to produce steel, creating a new era of greatly increased use of iron and steel that some contemporaries described as a new Iron Age. In the late 1850s, Henry Bessemer invented a new steelmaking process, that involved blowing air through molten pig iron to burn off carbon, and so to produce mild steel. This and other 19th-century and later steel making processes have displaced wrought iron. Today, wrought iron is no longer produced on a commercial scale, having been displaced by the functionally equivalent mild or low carbon steel.
Iron
Cast iron was first produced in China during 5th century BC, but was hardly in Europe until the medieval period. The earliest cast iron artifacts were discovered by archaeologists in what is now modern Luhe County, Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture, and architecture. During the medieval period, means were found in Europe of producing wrought iron from cast iron (in this context known as pig iron) using finery forges. For all these processes, charcoal was required as fuel.
Cast-iron architecture
Cast iron has been used for centuries and was used in architecture in the pre-modern period; for instance, the 13th century Indian "Konark Sun Temple" used iron beams.
Cast iron
Grey cast iron is characterised by its graphitic microstructure, which causes fractures of the material to have a grey appearance. It is the most commonly used cast iron and the most widely used cast material based on weight. Most cast irons have a chemical composition of 2.5–4.0% carbon, 1–3% silicon, and the remainder iron. Grey cast iron has less tensile strength and shock resistance than steel, but its compressive strength is comparable to low- and medium-carbon steel. These mechanical properties are controlled by the size and shape of the graphite flakes present in the microstructure and can be characterised according to the guidelines given by the ASTM.
Iron
"White" cast irons contain their carbon in the form of cementite, or iron carbide (FeC). This hard, brittle compound dominates the mechanical properties of white cast irons, rendering them hard, but unresistant to shock. The broken surface of a white cast iron is full of fine facets of the broken iron carbide, a very pale, silvery, shiny material, hence the appellation. Cooling a mixture of iron with 0.8% carbon slowly below 723 °C to room temperature results in separate, alternating layers of cementite and α-iron, which is soft and malleable and is called pearlite for its appearance. Rapid cooling, on the other hand, does not allow time for this separation and creates hard and brittle martensite. The steel can then be tempered by reheating to a temperature in between, changing the proportions of pearlite and martensite. The end product below 0.8% carbon content is a pearlite-αFe mixture, and that above 0.8% carbon content is a pearlite-cementite mixture.
SoHo, Manhattan
An American architectural innovation, cast iron was cheaper to use for facades than materials such as stone or brick. Molds of ornamentation, prefabricated in foundries, were used interchangeably for many buildings, and a broken piece could be easily recast. The buildings could be erected quickly; some were built in four months. Despite the brief construction period, the quality of the cast-iron designs was not sacrificed. Bronze had previously been the metal most frequently used for architectural detail. Architects found that the relatively inexpensive cast iron could provide intricately designed patterns. Classical French and Italian architectural designs were often used as models for these facades. Because stone was the material associated with architectural masterpieces, cast iron, painted in neutral tints such as beige, was used to simulate stone.
Boiler
Cast iron may be used for the heating vessel of domestic water heaters. Although such heaters are usually termed "boilers" in some countries, their purpose is usually to produce hot water, not steam, and so they run at low pressure and try to avoid boiling. The brittleness of cast iron makes it impractical for high-pressure steam boilers.
Anchor plate
Anchor plates are made of cast iron, sometimes wrought iron or steel, and are often used on brick or other masonry-based buildings. They are commonly found in many older cities towns and villages in Europe and in more recent cities with substantial legacies of 18th- and 19th-century brick construction, such as New York, Philadelphia, St. Louis, Cincinnati and Charleston, South Carolina, and in older earthquake prone cities such as San Francisco, as well as across all of Europe. The tie-rod-and-plate assembly braces the masonry wall against lateral bowing.
Iron
Commercially available iron is classified based on purity and the abundance of additives. Pig iron has 3.5–4.5% carbon and contains varying amounts of contaminants such as sulfur, silicon and phosphorus. Pig iron is not a saleable product, but rather an intermediate step in the production of cast iron and steel. The reduction of contaminants in pig iron that negatively affect material properties, such as sulfur and phosphorus, yields cast iron containing 2–4% carbon, 1–6% silicon, and small amounts of manganese. Pig iron has a melting point in the range of 1420–1470 K, which is lower than either of its two main components, and makes it the first product to be melted when carbon and iron are heated together. Its mechanical properties vary greatly and depend on the form the carbon takes in the alloy.
Surface chemistry of cooking
Cast iron cookware is seasoned with oil. The surface of the cast iron is not very smooth; it has pits and peaks that are not conducive to cooking. Typically, the cookware is seasoned with oil. This process leaves a thin coat of oil in the pits and on top of the peaks on the surface of the pan. This thin coat actually polymerizes, making it durable and lasting. It also prevents the cast iron from rusting, which it is prone to do. The oil that is used in a seasoned pan combines with any liquid that is used in the cooking process and creates a good contact between pan and food. Even though the cast iron itself is a poor heat conductor, the oil makes the pan effective when it is at a high temperature.
Steel casting
Casting is often a valuable means to creating intricate parts used in machine applications where vibration is often a factor. Cast steel typically has a lower damping ability than cast iron, which can lead to excess vibration and noise in the form of ringing or squealing.
Casting (metalworking)
Shell molding is similar to sand casting, but the molding cavity is formed by a hardened "shell" of sand instead of a flask filled with sand. The sand used is finer than sand casting sand and is mixed with a resin so that it can be heated by the pattern and hardened into a shell around the pattern. Because of the resin and finer sand, it gives a much finer surface finish. The process is easily automated and more precise than sand casting. Common metals that are cast include cast iron, aluminium, magnesium, and copper alloys. This process is ideal for complex items that are small to medium-sized.
Cast bullet
Firearms projectiles were being cast in the 14th century. Iron was used for cannon, while lead was the preferred material for small arms. Lead was more expensive than iron, but it was softer and less damaging to the relatively weak iron barrels of early muskets. Lead could be cast in a ladle over a wood fire used for cooking or home heating, while casting iron required higher temperatures. Greater density of lead allowed lead bullets to retain velocity and energy better than iron bullets of the same weight and initial firing velocity.
Swaging, rather than casting, became a preferred manufacturing technique during the 19th century industrial revolution; but cast bullets remained popular in early rimmed black powder cartridges like the .32-20 Winchester, .32-40 Ballard, .38-40 Winchester, .38-55 Winchester, .44-40 Winchester, .45 Colt, and .45-70. Disadvantages became evident as loadings shifted to smokeless powder in the late 19th century. Higher velocity smokeless powder loadings caused lead to melt and be torn from soft bullets to remain in the barrel after firing in small deposits called "leading".. Manufacturers of high-velocity military ammunition modified their bullet swaging process to apply a thin sheet of stronger metal over the soft lead bullet. Although it took several decades to devise bullet jacket alloys and manufacturing procedures to duplicate the accuracy of cast bullets at lower velocities; jacketed bullets were more accurate at the velocity of 20th century military rifle cartridges. Jacketed bullets also functioned more reliably and are less likely to be deformed in the mechanical loading process of self-loading pistols and machine-guns.
Metal furniture
Cast Iron is used mainly for outdoor finishings and settings, such as those used for bench legs and solid iron tables. It is suited to outdoor use due to its hardness, heaviness and general tough composition. The main disadvantage to this is that it, being a relatively pure form of Iron is subject to corrosion at the hands of the moisture and air.
Cast-iron cookware
Cast-iron cookware was especially popular among homemakers during the first half of the 20th century. It was a cheap, yet durable cookware. Most American households had at least one cast-iron cooking pan, and brands such as Griswold, which began manufacturing in 1865, Wagner Ware, which began manufacturing in 1881, and Lodge Manufacturing, which entered the marketplace in 1896 as Blacklock Foundry, all competed for market share. The 20th century also saw the introduction and popularization of enamel-coated cast-iron cookware.
List of cast-iron cookware manufacturers
Milo is a Los Angeles based company that manufactures kitchen essentials. They launched in 2018 with a cast iron enameled Dutch Oven. They sell exclusively online from their website and have a lifetime warranty on their products.
Field Skillets are manufactured in Wisconsin and Indiana and the focus is on creating lighter weight cast iron. The pans have a smooth finish.
Several companies import cast-iron cookware of Chinese manufacture and market these products in America. Known American marketers of Chinese cast-iron cooking equipment include Bayou Classic, Camp Chef, Coleman, Old Mountain and Texsport.
William Kelly (inventor)
Before the technique of injecting air into molten iron was re-discovered by Kelly and by Bessemer, iron was available as cast iron, a strong but brittle metal made in a blast furnace by treating iron ore with coke derived from coal, and wrought iron, a more malleable and flexible metal made by heating iron ore in a low oxygen environment in a bloomery heated by charcoal and producing "blooms", which were 100 to 200 pound lumps of very low carbon iron mixed with slag. The blooms then had to be worked repeatedly by hammering with a helve hammer or later a steam hammer and folding it to work out the slag. This could in turn be converted to steel by heating it for prolonged periods sealed in stone boxes with charcoal, to add back carbon. The resulting steel could then be formed into larger shapes by heating it to welding temperature and hammering it together into a mass. Other laborious and expensive methods made small amounts of steel from special ores.
Wrought iron
Wrought iron is no longer produced on a commercial scale. Many products described as wrought iron, such as guard rails, garden furniture and gates, are actually made of mild steel. They retain that description because they are made to resemble objects which in the past were wrought (worked) by hand by a blacksmith (although many decorative iron objects, including fences and gates, were often cast rather than wrought).
Cast-iron architecture
Cast iron also became the standard support structure in the construction of greenhouses, and this type of design led to the monumental Crystal Palace built in London in 1851. Designed by Joseph Paxton, the glass-and-cast-iron structure was much imitated around the world.
Science and technology of the Han dynasty
A blast furnace converts raw iron ore into pig iron, which can be remelted in a cupola furnace to produce cast iron. The earliest specimens of cast iron found in China date to the 5th century BCE during the late Spring and Autumn period, yet the oldest discovered blast furnaces date to the 3rd century BCE and the majority date to the period after Emperor Wu of Han (r. 141–87 BCE) established a government monopoly over the iron industry in 117 BCE (most of the discovered iron works sites built before this date were merely foundries which recast iron that had been smelted elsewhere). Iron ore smelted in blast furnaces during the Han was rarely if ever cast directly into permanent molds; instead, the pig iron scraps were remelted in the cupola furnace to make cast iron. Cupola furnaces utilized a cold blast traveling through tuyere pipes from the bottom and over the top where the charge of charcoal and pig iron was introduced. The air traveling through the tuyere pipes thus became a hot blast once it reached the bottom of the furnace.
Casting (metalworking)
The process is suitable for repeatable production of net shape components from a variety of different metals and high performance alloys. Although generally used for small castings, this process has been used to produce complete aircraft door frames, with steel castings of up to 300 kg and aluminium castings of up to 30 kg. Compared to other casting processes such as die casting or sand casting, it can be an expensive process. However, the components that can be produced using investment casting can incorporate intricate contours, and in most cases the components are cast near net shape, so require little or no rework once cast.
Cast iron
Cast-iron pots were made at many English blast furnaces at the time. In 1707, Abraham Darby patented a method of making pots (and kettles) thinner and hence cheaper than his rivals could. This meant that his Coalbrookdale furnaces became dominant as suppliers of pots, an activity in which they were joined in the 1720s and 1730s by a small number of other coke-fired blast furnaces.
Wrought iron
Wrought iron has been used for decades as a generic term across the gate and fencing industry, even though mild steel is used for manufacturing these 'wrought iron' gates. This is mainly because of the limited availability of true wrought iron. Steel can also be hot-dip galvanised to prevent corrosion, which cannot be done with wrought iron.
Lugged steel frame construction
Lugs used today on higher performance bicycles are investment cast (aka lost wax process). Copies of the lugs are made in wax, and they are attached together into a "tree". The tree is surrounded by ceramic and fired in a kiln, thereby melting the wax and setting the ceramic. Finally, molten steel is poured in to produce the lug. Cast lugs have many advantages over stamped lugs: they allow much finer detail, tighter tolerances (and correspondingly less manipulation and file work), and more accurate angles, and they can be made from superior materials (chromoly or stainless steel). The disadvantages of cast lugs are few: casting doesn't allow for long points or cutouts (done for aesthetic appeal), it is difficult to bend the lug to change the angle (requiring framebuilders to order lug sets that precisely match the desired frame geometry), and they are more expensive.
Wealden iron industry
The Lamberhurst Foundry is believed to have been the maker in 1710–14 of some of the earliest cast-iron railings produced in England, which they made for St Paul's Cathedral, despite the objections of Christopher Wren, who did not want a fence around the Cathedral at all, and said that if there had to be one it should be of wrought rather than cast iron. The railings surrounded the cathedral, including seven gates. It weighed two hundred tons and cost six pence a pound. The total cost was £11,202. No further railings are known to have been cast in the Weald. Other early uses of cast iron railings were at Cambridge Senate House and at St Martin-in-the-Fields, London.
Body piercing materials
316 stainless steel, also referred to as marine grade stainless steel, is a chromium, nickel, molybdenum alloy of steel that exhibits relatively good strength and corrosion resistance. Along with the titanium alloy Ti6Al4V, 316 stainless is a common choice of material for biomedical implants. Although Ti6Al4V provides greater strength per weight and corrosion resistance, 316 stainless components can be more economical to produce. However, immune system reaction to nickel is a potential complication of 316.[1][2] Implants and equipment that are put under pressure (bone fixation screws, prostheses, body piercing jewelry) are made out of austenitic steel, often 316L and 316LVM compliant to ASTM F138.[3] 316 surgical steel is used in the manufacture and handling of food and pharmaceutical products where it is often required in order to minimize metallic contamination. ASTM F138[3]-compliant steel is also used in the manufacture of body piercing jewellery[4] and body modification implants.
SoHo, Manhattan
SoHo boasts the greatest collection of cast-iron architecture in the world. Approximately 250 cast-iron buildings stand in New York City, and the majority are in SoHo. Cast iron was initially used as a decorative front over a pre-existing building. With the addition of modern, decorative facades, older industrial buildings were able to attract new commercial clients. Most of these facades were constructed during the period from 1840 to 1880. In addition to revitalizing older structures, buildings in SoHo were later designed to feature the cast iron.
Rain gutter
Cast iron gutters were introduced in the late 18th century as an alternative to lead. Cast iron enabled eaves gutters to be mass-produced: they were rigid and non-porous while lead could only be used as a liner within timber gutters. Installation was a single process and didn't require heat. They could be attached directly to the fascia board. Cast iron gutters are still specified for restoration work in conservation areas, but are usually replaced with cast aluminium made to the same profile. Extruded aluminium gutters can be made to a variety of profiles from a roll of aluminium sheet on site in lengths of up to 30m. They feature internal brackets at 400mm spacing.
Steel
The carbon content of steel is between 0.002% and 2.14% by weight for plain iron–carbon alloys. These values vary depending on alloying elements such as manganese, chromium, nickel, tungsten, and so on. Basically, steel is an iron-carbon alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction. Too little carbon content leaves (pure) iron quite soft, ductile, and weak. Carbon contents higher than those of steel make a brittle alloy commonly called pig iron. While iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include: manganese, nickel, chromium, molybdenum, boron, titanium, vanadium, tungsten, cobalt, and niobium. Additional elements, most frequently considered undesirable, are also important in steel: phosphorus, sulfur, silicon, and traces of oxygen, nitrogen, and copper.
Iron
Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is relatively soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon, from the smelting process. A certain proportion of carbon (between 0.002% and 2.1%) produces steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, which has a high carbon content. Further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with other metals (alloy steels) are by far the most common industrial metals because they have a great range of desirable properties and iron-bearing rock is abundant.
Corrugated galvanised iron
Corrugated galvanised iron or steel (colloquially corrugated iron (near universal), wriggly tin (taken from UK military slang), pailing (in Caribbean English), corrugated sheet metal (in North America) and occasionally abbreviated CGI) is a building material composed of sheets of hot-dip galvanised mild steel, cold-rolled to produce a linear corrugated pattern in them. Although it is still popularly called "iron" in the UK, the material used is actually steel (which is iron alloyed with carbon for strength, commonly 0.3% carbon), and only the surviving vintage sheets may actually be made up of 100% iron. The corrugations increase the bending strength of the sheet in the direction perpendicular to the corrugations, but not parallel to them, because the steel must be stretched to bend perpendicular to the corrugations. Normally each sheet is manufactured longer in its strong direction.
Steel
Modern steels are made with varying combinations of alloy metals to fulfill many purposes. Carbon steel, composed simply of iron and carbon, accounts for 90% of steel production. Low alloy steel is alloyed with other elements, usually molybdenum, manganese, chromium, or nickel, in amounts of up to 10% by weight to improve the hardenability of thick sections. High strength low alloy steel has small additions (usually < 2% by weight) of other elements, typically 1.5% manganese, to provide additional strength for a modest price increase.
Cast iron
Cast iron is sometimes melted in a special type of blast furnace known as a cupola, but in modern applications, it is more often melted in electric induction furnaces or electric arc furnaces. After melting is complete, the molten cast iron is poured into a holding furnace or ladle.
Cast iron
Developed in 1948, "nodular" or "ductile cast iron" has its graphite in the form of very tiny nodules with the graphite in the form of concentric layers forming the nodules. As a result, the properties of ductile cast iron are that of a spongy steel without the stress concentration effects that flakes of graphite would produce. Tiny amounts of 0.02 to 0.1% magnesium, and only 0.02 to 0.04% cerium added to these alloys slow the growth of graphite precipitates by bonding to the edges of the graphite planes. Along with careful control of other elements and timing, this allows the carbon to separate as spheroidal particles as the material solidifies. The properties are similar to malleable iron, but parts can be cast with larger sections.
Sink
Enamel over cast iron is a popular material for kitchen and bathroom sinks. Heavy and durable, these sinks can also be manufactured in a very wide range of shapes and colors. Like stainless steel, they are very resistant to hot or cold objects, but they can be damaged by sharp impacts and once the glass surface is breached, the underlying cast iron will often corrode, spalling off more of the glass. Aggressive cleaning will dull the surface, leading to more dirt accumulation. Enamel over steel is a similar-appearing but far less rugged and less cost-effective alternative.
Solid ceramic sinks have many of the same characteristics as enamel over cast iron, but without the risk of surface damage leading to corrosion.
Cookware and bakeware
Cast iron is a porous material that rusts easily. As a result, it typically requires seasoning before use. Seasoning creates a thin layer of oxidized fat over the iron that coats and protects the surface, and prevents sticking.
Window shutter hardware
Wrought Iron - literally "hammered" iron. Early on, billets of cast iron were transferred to iron forges. The cast iron billets were heated to near-molten and flattened under a heavy water-powered drop hammer - kind of a see-saw with a couple of hundred pound chunk of iron "hammer" on one end of a heavy wooden beam and a rotating wooden cam acting on the other end to lift and drop the hammer in time with the turning of the water wheel. Valley Forge took its name from a small shop such as this which the British burned, unopposed, on their way to Philadelphia in 1776. Once hammered thinner and longer the billet would be doubled backed on its length, re-heated and re-hammered. This repeated exposure to the oxygen in the fire and the compressing blows of the hammer would burn and drive impurities from the billet. The iron being forged would become increasingly malleable with each heat to which it was subjected. The finest forging iron was multi-layered and nearly pure iron. To the best of my knowledge, there is no new wrought iron being produced today. Well, maybe Japanese Samurai swordsmiths still make their own – but if it's in Home Depot and says "Wrought Iron" it isn't.
Pig iron
Pig iron is an intermediate product of the iron industry, also known as crude iron, which is first obtained from a smelting furnace in the form of oblong blocks. Pig iron has a very high carbon content, typically 3.8–4.7%, along with silica and other constituents of dross, which makes it very brittle and not useful directly as a material except for limited applications. Pig iron is made by smelting iron ore into a transportable ingot of impure high carbon-content iron in a blast furnace as an ingredient for further processing steps. The traditional shape of the molds used for pig iron ingots was a branching structure formed in sand, with many individual ingots at right angles to a central channel or "runner", resembling a litter of piglets being suckled by a sow. When the metal had cooled and hardened, the smaller ingots (the "pigs") were simply broken from the runner (the "sow"), hence the name "pig iron". As pig iron is intended for remelting, the uneven size of the ingots and the inclusion of small amounts of sand caused only insignificant problems considering the ease of casting and handling them.
Blacksmith
When iron ore is smelted into usable metal, a certain amount of carbon is usually alloyed with the iron. (Charcoal is almost pure carbon.) The amount of carbon significantly affects the properties of the metal. If the carbon content is over 2%, the metal is called cast iron, because it has a relatively low melting point and is easily cast. It is quite brittle, however, and cannot be forged so therefore not used for blacksmithing. If the carbon content is between 0.25% and 2%, the resulting metal is tool grade steel, which can be heat treated as discussed above. When the carbon content is below 0.25%, the metal is either "wrought iron (wrought iron is not smelted and cannot come from this process) " or "mild steel." The terms are never interchangeable. In preindustrial times, the material of choice for blacksmiths was wrought iron. This iron had a very low carbon content, and also included up to 5% of glassy iron silicate slag in the form of numerous very fine stringers. This slag content made the iron very tough, gave it considerable resistance to rusting, and allowed it to be more easily "forge welded," a process in which the blacksmith permanently joins two pieces of iron, or a piece of iron and a piece of steel, by heating them nearly to a white heat and hammering them together. Forge welding is more difficult with modern mild steel, because it welds in a narrower temperature band. The fibrous nature of wrought iron required knowledge and skill to properly form any tool which would be subject to stress. Modern steel is produced using either the blast furnace or arc furnaces. Wrought iron was produced by a labor-intensive process called "puddling", so this material is now a difficult-to-find specialty product. Modern blacksmiths generally substitute mild steel for making objects traditionally of wrought iron. Sometimes they use electrolytic-process pure iron.
Wok
Woks can also be made from aluminium. Although an excellent conductor of heat, it has somewhat inferior thermal capacity as cast iron or carbon steel, it loses heat to convection much faster than carbon steel, and it may be constructed much thinner than cast iron. Although anodized aluminium alloys can stand up to constant use, plain aluminium woks are too soft and damage easily. Aluminium is mostly used for wok lids.
Cast-iron cookware
Cast iron fell out of favor in the 1960s and 1970s, as teflon-coated aluminum non-stick cookware was introduced and quickly became the item of choice in many kitchens. The decline in daily use of cast-iron cookware contributed to the closure of nearly all the iron cookware manufacturers in the United States. Many went out of business in the 1920s as seen in the List of cast-iron cookware manufacturers. Others were absorbed by other cookware manufacturers, such as the buyout of Griswold by Wagner in 1957, which was then purchased by the American Culinary Corporation. By the end of the 20th century, Lodge Manufacturing was the only remaining manufacturer of cast-iron cookware in the United States.
Ferrous metallurgy
The earliest cast iron artifacts, dating to 5th century BC, were discovered by archaeologists in what is now modern Luhe County, Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture and architecture. Around 500 BC, metalworkers in the southern state of Wu achieved a temperature of 1130 °C. At this temperature, iron combines with 4.3% carbon and melts. The liquid iron can be cast into molds, a method far less laborious than individually forging each piece of iron from a bloom.
List of alloys
Aluminium also forms complex metallic alloys, like β–Al–Mg, ξ'–Al–Pd–Mn, and T–AlMn.Most iron alloys are steels, with carbon as a major alloying element.
Modern steels are made with varying combinations of alloy metals to fulfill many purposes. Carbon steel, composed simply of iron and carbon, accounts for 90% of steel production. Low alloy steel is alloyed with other elements, usually molybdenum, manganese, chromium, or nickel, in amounts of up to 10% by weight to improve the hardenability of thick sections. High strength low alloy steel has small additions (usually < 2% by weight) of other elements, typically 1.5% manganese, to provide additional strength for a modest price increase.
Wok
Cast iron woks form a more stable carbonized layer of seasoning which makes it less prone to food sticking on the pan. While cast iron woks are superior to carbon steel woks in heat retention and uniform heat distribution, they respond slowly to heat adjustments and are slow to cool once taken off the fire. Because of this, food cooked in a cast iron wok must be promptly removed from the wok as soon as it is done to prevent overcooking. Chinese-style cast iron woks, although relatively light, are fragile and are prone to shattering if dropped or mishandled.
Equivalent carbon content
For cast iron the equivalent carbon content (CE) concept is used to understand how alloying elements will affect the heat treatment and casting behavior. It is used as a predictor of strength in cast irons because it gives an approximate balance of austenite and graphite in final structure. The following formulas are used to determine the CE in cast irons:
Cast iron
The best way of using cast iron for bridge construction was by using arches, so that all the material is in compression. Cast iron, again like masonry, is very strong in compression. Wrought iron, like most other kinds of iron and indeed like most metals in general, is strong in tension, and also tough – resistant to fracturing. The relationship between wrought iron and cast iron, for structural purposes, may be thought of as analogous to the relationship between wood and stone.
Stirling and Dunfermline Railway
Cast iron is rigid and brittle so that deflection of the rails resulted in breakages. In 1785 a wearing surface of Swedish malleable iron, 1¾ inches broad, and ¾ of an inch thick, was tried with great success because of its ability to flex with the timber. The running resistance was also remarkably low.
Casting (metalworking)
Permanent mold casting is a metal casting process that employs reusable molds ("permanent molds"), usually made from metal. The most common process uses gravity to fill the mold. However, gas pressure or a vacuum are also used. A variation on the typical gravity casting process, called slush casting, produces hollow castings. Common casting metals are aluminum, magnesium, and copper alloys. Other materials include tin, zinc, and lead alloys and iron and steel are also cast in graphite molds. Permanent molds, while lasting more than one casting still have a limited life before wearing out.
Frying pan
Traditionally, frying pans were made of cast iron. Although cast iron is still popular today, especially for outdoor cooking, most frying pans are now made from metals such as aluminium or stainless steel. The materials and construction method used in modern frying pans vary greatly and some typical materials include:
Cast bullet
A cast bullet is made by allowing molten metal to solidify in a mold. Most cast bullets are made of lead alloyed with tin and antimony; but zinc alloys have been used when lead is scarce, and may be used again in response to concerns about lead toxicity. Most commercial bullet manufacturers use swaging in preference to casting, but bullet casting remains popular with handloaders.
Steel casting
Cast parts often require machining to achieve accurate tolerances and desired surface finishes. Carbon steel is the easiest type of steel to machine. High-carbon steel can be more time consuming to cut or grind, and will wear tools faster. Low-carbon steel can get gummy, making it difficult to work with.
List of cast-iron cookware manufacturers
Borough Furnace is based in Syracuse, NY. All of their products are designed by John Truex and produced in their sustainable facility, powered by renewables. Borough Furnace was also the first cookware company to season their products with flax seed oil and to advertise their usage of recycled materials.FINEX is based in Portland, Oregon and manufactures cast-iron cookware in the US. FINEX Cast Iron Cookware Company is a small team dedicated to making heirloom quality cast-iron cookware in the US.Nest Homeware is a small company based in Providence, RI, specializing in beautifully designed cast iron cookware. Nest is managed by its founder and principal designer, Matt Cavallaro.TAKU manufactures cast-iron cookware (pan, pots, teapots...) in Taichung, Taiwan. TAKU also uses local artists to create unique cast-iron cookware.Stargazer Cast Iron is based in Allentown, Pennsylvania, and produces cookware in the US. They are an e-commerce retailer, and their products can only be purchased direct via the company's website. Stargazer Cast Iron's cookware is available bare or seasoned.Marquette Castings designs investment cast-iron cookware in Royal Oak, Michigan, and manufactures in the US and China.
Ferrous metallurgy
The preferred method of iron production in Europe until the development of the puddling process in 1783-84. Cast iron development lagged in Europe because wrought iron was the desired product and the intermediate step of producing cast iron involved an expensive blast furnace and further refining of pig iron to cast iron, which then required a labor and capital intensive conversion to wrought iron.
Waffle iron
Traditional waffle irons are attached to tongs with wooden handles and are held over an open flame, or set on a stove. Most modern waffle irons are self-contained tabletop electrical appliances, heated by an electric heating element controlled by an internal thermostat. There are also two variants of the electric iron: one with removable plates and ones with non-removable plates. Professional waffle makers are usually made of cast iron whereas domestic models are often teflon coated. Many have a light that goes off when the iron is at the set temperature. Most modern waffle irons - particularly cast aluminum ones - are coated with a non-stick coating (e.g. teflon) to prevent the waffles from sticking to them. Cast-iron waffle makers are usually not coated and require seasoning like a cast-iron frying pan.
Iron
Pig iron is not pure iron, but has 4–5% carbon dissolved in it with small amounts of other impurities like sulfur, magnesium, phosphorus, and manganese. As the carbon is the major impurity, the iron (pig iron) becomes brittle and hard. Removing the other impurities results in cast iron, which is used to cast articles in foundries; for example stoves, pipes, radiators, lamp-posts, and rails.
List of cast-iron cookware manufacturers
With the exception of Lodge Manufacturing, most American manufacturers of cast iron from this era such as Atlanta Stove Works, have been acquired by other corporations and no longer produce cast-iron cookware in the United States; however, cast-iron pots and pans from the early 20th century continue to see daily use among many households in the present day. They are also highly sought after by antique collectors and dealers. Among the rarest products were those produced in 1920. Exporting and trade flourished creating a shortage for U.S. consumers. The Atlanta 32 box became one of the rarest items in 1920 production. Exporting overseas created an increase in industry output for the following years. Manufacturing and industry contributed to the prosperity and growth of an era that would be known as the "Roaring 20's" marking a post-war national lifestyle change.Founded as the Seldon and Griswold Manufacturing Company, the Griswold company became known as the premier manufacturer of high-quality cast-iron kitchen items in the United States. The Griswold cast iron foundry was based in Erie, Pennsylvania; and until the early 1900s cast-iron items from this company were marked with an "ERIE" logo. In the early 1900s this was changed to a "GRISWOLD" logo, and it is this logo that is most commonly associated with Griswold cast-iron cookware.
Steel belt
They are generally made from carbon steel or stainless steel. Stainless steel belts are corrosion resistant and provide excellent surface quality. Stainless steel belts are used primarily in the chemical, food, rubber, plastic, wood, and laminate industries. Carbon steel belts are energy efficient and ideal for applications necessitating radiant heating of products or in high-temperature applications that might exceed the annealing temperatures of stainless steel belts also carbon steel belts can more evenly distributed heat since most stainless steel alloys are comparatively poor heat conductors. Carbon steel belts are used primarily in food processing, transport, and bake ovens. Textured Steel is also a commonly found belt material. The main purpose of using textured steel material is for its non-stick capabilities. This works well in the laminate industry.
Cast iron
High-chromium white iron alloys allow massive castings (for example, a 10-tonne impeller) to be sand cast, as the chromium reduces cooling rate required to produce carbides through the greater thicknesses of material. Chromium also produces carbides with impressive abrasion resistance. These high-chromium alloys attribute their superior hardness to the presence of chromium carbides. The main form of these carbides are the eutectic or primary MC carbides, where "M" represents iron or chromium and can vary depending on the alloy's composition. The eutectic carbides form as bundles of hollow hexagonal rods and grow perpendicular to the hexagonal basal plane. The hardness of these carbides are within the range of 1500-1800HV
Technological and industrial history of the United States
Although steel is an alloy of iron and a small amount of carbon, historically steel and iron-making were intended for different products given the high costs of steel over wrought iron. The main difficulty with making steel is that its higher melting point than pig or cast iron was not easily achievable in large-scale production until methods that introduced air or oxygen to oxidize the carbon in the molten pig iron were developed, allowing the direct conversion of molten pig iron to molten steel.
Cast iron
In the west, where it did not become available until the 15th century, its earliest uses included cannon and shot. Henry VIII initiated the casting of cannon in England. Soon, English iron workers using blast furnaces developed the technique of producing cast-iron cannons, which, while heavier than the prevailing bronze cannons, were much cheaper and enabled England to arm her navy better. The technology of cast iron was transferred from China. Al-Qazvini in the 13th century and other travellers subsequently noted an iron industry in the Alburz Mountains to the south of the Caspian Sea. This is close to the silk route, so that the use of technology derived from China is conceivable. The ironmasters of the Weald continued producing cast irons until the 1760s, and armament was one of the main uses of irons after the Restoration.
Cast-iron cookware
Enameled cast iron is cast iron that has a vitreous enamel glaze applied to the surface. The fusion of the glaze with the cast iron prevents rusting, eliminates the need to season the metal, and allows more thorough cleaning. Enameled cast iron is excellent for slow cooking and drawing flavor from foods. Furthermore, pigments used in the enameling process can produce vibrant colors.
Wrought iron
Wrought iron may be welded in the same manner as mild steel, but the presence of oxide or inclusions will give defective results.
The material has a rough surface, so it can hold platings and coatings better. For instance, a galvanic zinc finish applied to wrought iron is approximately 25–40% thicker than the same finish on steel. In Table 1, the chemical composition of wrought iron is compared to that of pig iron and carbon steel. Although it appears that wrought iron and plain carbon steel have similar chemical compositions, that is deceiving. Most of the manganese, sulfur, phosphorus, and silicon are incorporated into the slag fibers present in the wrought iron, so, really, wrought iron is purer than plain carbon steel.
Cast-iron architecture
It was in 18th-century Britain that new production methods first allowed cast iron to be produced cheaply enough and in large enough quantities to regularly be used in large building projects. New production methods included using steam engine powered blast air, which allowed higher blast furnace temperatures, which in turn allowed the use of more limestone to be added with the iron ore charge. The higher furnace temperatures made the slag produced with the additional lime to flow more freely. The calcium and magnesium in the lime helped tie up sulfur, which allowed the use of coke for fuel. The higher furnace temperatures also increased the furnace capacity.
Carbon steel
Mild steel (iron containing a small percentage of carbon, strong and tough but not readily tempered), also known as plain-carbon steel and low-carbon steel, is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications. Mild steel contains approximately 0.05–0.25% carbon making it malleable and ductile. Mild steel has a relatively low tensile strength, but it is cheap and easy to form; surface hardness can be increased through carburizing.
Rail transport
Cast iron used in rails proved unsatisfactory because it was brittle and broke under heavy loads. The wrought iron invented by John Birkinshaw in 1820 replaced cast iron. Wrought iron (usually simply referred to as "iron") was a ductile material that could undergo considerable deformation before breaking, making it more suitable for iron rails. But iron was expensive to produce until Henry Cort patented the puddling process in 1784. In 1783 Cort also patented the rolling process, which was 15 times faster at consolidating and shaping iron than hammering. These processes greatly lowered the cost of producing iron and rails. The next important development in iron production was hot blast developed by James Beaumont Neilson (patented 1828), which considerably reduced the amount of coke (fuel) or charcoal needed to produce pig iron. Wrought iron was a soft material that contained slag or "dross". The softness and dross tended to make iron rails distort and delaminate and they lasted less than 10 years. Sometimes they lasted as little as one year under high traffic. All these developments in the production of iron eventually led to replacement of composite wood/iron rails with superior all iron rails.
Steel
Iron is the base metal of steel. Iron is able to take on two crystalline forms (allotropic forms), body centered cubic and face centered cubic, depending on its temperature. In the body-centered cubic arrangement, there is an iron atom in the center and eight atoms at the vertices of each cubic unit cell; in the face-centered cubic, there is one atom at the center of each of the six faces of the cubic unit cell and eight atoms at its vertices. It is the interaction of the allotropes of iron with the alloying elements, primarily carbon, that gives steel and cast iron their range of unique properties.
Crucible steel
Iron alloys are most broadly divided by their carbon content: cast iron has 2-4% carbon impurities; wrought iron oxidizes away most of its carbon, to less than 0.1%. The much more valuable steel has a delicately intermediate carbon fraction, and its material properties range according to the carbon percentage: high carbon steel is stronger but more brittle than low carbon steel. Crucible steel sequesters the raw input materials from the heat source, allowing precise control of carburization (raising) or oxidation (lowering carbon content). Fluxes, such as limestone, could be added to the crucible to remove or promote sulfur, silicon, and other impurities, further altering its material qualities.
Cast iron
Carbon (C) ranging from 1.8 to 4 wt%, and silicon (Si) 1–3 wt% are the main alloying elements of cast iron. Iron alloys with lower carbon content (~0.8%) are known as steel. While this technically makes the Fe–C–Si system ternary, the principle of cast iron solidification can be understood from the simpler binary iron–carbon phase diagram. Since the compositions of most cast irons are around the eutectic point (lowest liquid point) of the iron–carbon system, the melting temperatures usually range from , which is about lower than the melting point of pure iron of .
Cast-iron cookware
While enamel-coated cast iron doesn't have the seasoning and cleaning issues of bare cast iron, a similar style of enamel-coated cast iron can cost three or four times its bare cast iron counterpart. For those seeking to reduce iron in their diet, enameled cast iron limits the leaching of dietary iron into food. However, some of the benefits of bare cast iron, such as the ability to withstand searing heat and resist sticking, are lost through enameling. In addition, chipping of the enamel coating can occur if the pan is dropped, overheated, or cold water is added to a hot pot.
Cast-iron cookware
A proper cast iron seasoning protects the cookware from rusting, provides a non-stick surface for cooking, and reduces food interaction with the iron of the pan. However, exposure to acidic foods such as tomatoes removes the seasoning, and the cookware must be re-seasoned again. Enamel-coated cast-iron pans do not need seasoning, as the enamel coating prevents rust in most instances. It is recommended to maintain the seasoning frequently to keep the food from sticking to the iron.
Garter spring
Carbon steel wire is typically used for garter springs due to its affordable price and usability, in comparison to stainless steel. Carbon steel springs tend to have very high yield strengths, and are able to return to their original shape when temporarily deformed. The carbon content in carbon steel wires range from 0.50 to 0.95 percent. This relatively small amount of carbon is enough to improve the toughness of the spring. The close proximity to oil and high-pressure engines mean heat treated garter springs are essential for enduring temperatures over 100 °C (212 °F). However, carbon steel is not suitable for highly corrosive environments; stainless steel would be a more viable option. Stainless steel differs from carbon steel in the amount of chromium present; stainless steel has between 10.5% to 11% chromium by mass, while carbon steel has about 1%.
Cast-iron cookware
However, cast iron has seen a resurgence of its popularity in specialty markets. Through cooking shows, celebrity chefs have brought renewed attention to traditional cooking methods, especially the use of cast iron. In the 2010s, small startup companies such as FINEX, Element Cookware, Smithey Ironware Company, Marquette Castings, Stargazer Cast Iron and Borough Furnace began producing cast-iron cookware designs for specialty cooking markets.
Structural material
Cast iron retains high strength in fires, despite its low melting point. It is usually around 95% iron, with between 2.1% and 4% carbon and between 1% and 3% silicon. It does not corrode as easily as steel.
Cast iron
Malleable iron starts as a white iron casting that is then heat treated for a day or two at about and then cooled over a day or two. As a result, the carbon in iron carbide transforms into graphite and ferrite plus carbon (austenite). The slow process allows the surface tension to form the graphite into spheroidal particles rather than flakes. Due to their lower aspect ratio, the spheroids are relatively short and far from one another, and have a lower cross section vis-a-vis a propagating crack or phonon. They also have blunt boundaries, as opposed to flakes, which alleviates the stress concentration problems found in grey cast iron. In general, the properties of malleable cast iron are more like those of mild steel. There is a limit to how large a part can be cast in malleable iron, as it is made from white cast iron.
Cast iron
Because cast iron is comparatively brittle, it is not suitable for purposes where a sharp edge or flexibility is required. It is strong under compression, but not under tension. Cast iron was invented in China in the 5th century BC and poured into moulds to make ploughshares and pots as well as weapons and pagodas. Although steel was more desirable, cast iron was cheaper and thus was more commonly used for implements in ancient China, while wrought iron or steel was used for weapons. The Chinese developed a method of annealing cast iron by keeping hot castings in an oxidizing atmosphere for a week or longer in order to burn off some carbon near the surface in order to keep the surface layer from being too brittle.
Steelmaking
Cast iron is a hard brittle material that is difficult to work, whereas steel is malleable, relatively easily formed and a versatile material. For much of human history, steel has only been made in small quantities. Since the invention of the Bessemer process in the 19th century and subsequent technological developments in injection technology and process control, mass production of steel has become an integral part of the global economy and a key indicator of modern technological development. The earliest means of producing steel was in a bloomery.
Lost-foam casting
Commonly cast metals include cast irons, aluminium alloys, steels, and nickel alloys; less frequently stainless steels and copper alloys are also cast. The size range is from to several tonnes (tons). The minimum wall thickness is and there is no upper limit. Typical surface finishes are from 2.5 to 25 µm (100 to 1000 µin) RMS. Typical linear tolerances are ±0.005 mm/mm (0.005 in/in).
Malleable iron
Before the widespread use of malleable iron in everyday items, heavy-duty bench vises were made from cast steel. The use of cast steel has rapidly declined in most application due to its poor castability, and hence high-quality cast vises (as opposed to forged ones), among other tools and machine elements, are now almost exclusively made of malleable iron.