Iron-Cementite meta-stable diagram. QtubIronPillarJPG|thumb|right| Iron pillar at Delhi India containing 98% wrought iron]] Wrought iron is commercially pure Iron. Ductile iron, also called ductile cast iron, spheroidal graphite iron, or nodular cast iron, is a type of Cast iron invented in 1943 by

Cast iron usually refers to grey cast iron, but identifies a large group of ferrous alloys, which solidify with a eutectic. Gray iron or grey iron was the original " Cast iron " Ferrous, in the chemical science realm indicates a bivalent iron compound (+2 oxidation state (as opposed to Ferric, which indicates a trivalent iron compound (+3 oxidation An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured due to its carbide impurities which allow cracks to pass straight through. Grey cast iron is named after its grey fractured surface, which occurs because the graphitic flakes deflect a passing crack and initiate countless new cracks as the material breaks.

Iron (Fe) accounts for more than 95 %wt of the alloy material, while the main alloying elements are carbon (C) and silicon (Si). Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 The amount of carbon in cast irons is 2. 1-4 %wt. Cast irons contain appreciable amounts of silicon, normally 1-3 %wt, and consequently these alloys should be considered ternary Fe-C-Si alloys. Despite this, the principles of cast iron solidification are understood from the binary iron-carbon phase diagram, where the eutectic point lies at 1154 °C and 4. A binary compound is a compound that contains two different elements such as NaCl (salt or Sodium chloride) 3 wt% carbon. Since cast iron has nearly this composition, its melting temperature of 1150 to 1200 °C is about 300 °C lower than the melting point of pure iron.

Cast iron tends to be brittle, except for malleable cast irons. Ductility is a mechanical property used to describe the extent to which materials can be deformed plastically or "stretched" into "wires" without Malleable iron is the oldest member of the family of Nodular irons Like all nodular irons malleable iron exhibits good Ductility. With its low melting point, good fluidity, castability, excellent machinability and wear resistance, cast irons have become an engineering material with a wide range of applications, including pipes, machine and car parts.

Production

Cast iron is made by remelting pig iron, often along with substantial quantities of scrap iron and scrap steel, and taking various steps to remove undesirable contaminants such as phosphorus and sulfur. Pig iron is the intermediate product of Smelting Iron ore with coke, usually with Limestone as a flux Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Depending on the application, carbon and silicon content are reduced to the desired levels, which may be anywhere from 2% to 3. 5% and 1% to 3% respectively. Other elements are then added to the melt before the final form is produced by casting. Casting is a manufacturing process by which a liquid material is (usually poured into a mold which

Iron is most commonly melted in a small blast furnace known as a cupola (see blast furnace for more details). A blast furnace is a type of metallurgical Furnace used for Smelting to produce metals generally Iron. A blast furnace is a type of metallurgical Furnace used for Smelting to produce metals generally Iron. After melting is complete, the molten iron is removed or ladled from the forehearth of the blast furnace. In Foundry work a ladle is a container used to transport and pour out molten metals A blast furnace is a type of metallurgical Furnace used for Smelting to produce metals generally Iron. This process was devised by the Chinese, whose innovative ideas revolutionized the field of metallurgy. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Metallurgy is a domain of Materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their Previously, iron was melted in an air furnace, which is a type of reverberatory furnace. A reverberatory furnace is a metallurgical or process Furnace that isolates the material being processed from contact with the Fuel, but not from contact

Varieties of cast iron

Grey cast iron

Cast iron drain, waste and vent piping in a Canadian timber-frame building in Mission, British Columbia in the 1980s. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page Mission is a Canadian district municipality, in the province of British Columbia and is situated on the north bank of the Fraser River overlooking the

Main article: Grey iron

Silicon is essential to making grey cast iron as opposed to white cast iron. Gray iron or grey iron was the original " Cast iron " When silicon is alloyed with ferrite and carbon in amounts of about 2 percent, the carbide of iron becomes unstable. Silicon causes the carbon to rapidly come out of solution as graphite, leaving a matrix of relatively pure, soft iron. The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon. Weak bonding between planes of graphite lead to a high activation energy for growth in that direction, resulting in thin, round flakes. In Chemistry, activation energy, also called midnight energy, is a term introduced in 1889 by the Swedish scientist Svante Arrhenius, that is defined This structure has several useful properties.

The metal expands slightly on solidifying as the graphite precipitates, resulting in sharp castings. The graphite content also offers good corrosion resistance. Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings

Graphite acts as a lubricant, improving wear resistance. The exceptionally high speed of sound in graphite gives cast iron a much higher thermal conductivity. Sound is a vibration that travels through an elastic medium as a Wave. In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. Since ferrite is so different in this respect (having heavier atoms, bonded much less tightly) phonons tend to scatter at the interface between the two materials. In Physics, a phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the Atomic lattice of a Solid In practical terms, this means that cast iron tends to “damp” mechanical vibrations (including sound), which can help machinery to run more smoothly. Sound' is Vibration transmitted through a Solid, Liquid, or Gas; particularly sound means those vibrations composed of Frequencies

All of the properties listed in the paragraph above ease the machining of grey cast iron. Conventional Machining, one of the most important material removal methods is a collection of material-working processes in which power-driven Machine tools, such as lathes The sharp edges of graphite flakes also tend to concentrate stress, allowing cracks to form much more easily, so that material can be removed much more efficiently. A stress concentration (often called stress raisers or stress risers) is a location in an object where stress is concentrated

Easier initiation of cracks can be a drawback once an item is finished, however: grey cast iron has less tensile strength and shock resistance than steel. Tensile strength \sigma_{UTS} or S_U is the Stress at which a material breaks or permanently deforms Toughness, in Materials science and Metallurgy, is the resistance to Fracture of a material when stressed. It is also difficult to weld.

Grey cast iron's high thermal conductivity and specific heat capacity are often exploited to make cast iron cookware and disc brake rotors. Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity Cast iron is used for cookware because it is non-toxic has excellent heat retention and diffusion properties and is easy to mold. The disc brake or disk brake is a device for slowing or stopping the rotation of a Wheel.

Other cast iron alloys

An illustration of furnace bellows operated by waterwheels, from the Nong Shu, by Wang Zhen, 1313 AD, during the Chinese Yuan Dynasty. A water wheel is a means of extracting power from the flow (or fall of water otherwise known as Hydropower. This article is about Wang Zhen agronomist and inventor For other historical figures with this name see Wang Zhen (disambiguation. The Yuan Dynasty ( Pinyin: Yuáncháo Dai Ön Ulus (Дай Юан Улс was a ruling Dynasty founded by the Mongol leader Kublai

With a lower silicon content and faster cooling, the carbon in white cast iron precipitates out of the melt as the metastable phase cementite, Fe₃C, rather than graphite. Metastability is a general scientific concept which describes states of delicate equilibrium Cementite or iron carbide is a Chemical compound with the formula Fe3C (or Fe2CFe and an Orthorhombic crystal structure The cementite which precipitates from the melt forms as relatively large particles, usually in a eutectic mixture where the other phase is austenite (which on cooling might transform to martensite). These eutectic carbides are much too large to provide precipitation hardening (as in some steels, where cementite precipitates might inhibit plastic deformation by impeding the movement of dislocations through the ferrite matrix). In Materials science, deformation is a change in the shape or size of an object due to an applied force. In Materials science, a dislocation is a Crystallographic defect, or irregularity within a Crystal structure. Rather, they increase the bulk hardness of the cast iron simply by virtue of their own very high hardness and their substantial volume fraction, such that the bulk hardness can be approximated by a rule of mixtures. In any case, they offer hardness at the expense of toughness. Hardness refers to various properties of Matter in the Solid phase that give it high resistance to various kinds of shape change when Force Toughness, in Materials science and Metallurgy, is the resistance to Fracture of a material when stressed. Since carbide makes up a large fraction of the material, white cast iron could reasonably be classified as a cermet. A cermet is a Composite material composed of Ceramic (cer and Metallic (met materials White iron is too brittle for use in many structural components, but with good hardness and abrasion resistance and relatively low cost, it finds use in such applications as the wear surfaces (impeller and volute) of slurry pumps, shell liners and lifter bars in ball mills and autogenous grinding mills, balls and rings in coal pulverisers and (conceivably?) balls for rolling-element bearings and the teeth of a backhoe's digging bucket (although the latter two applications would normally use high quality wrought high-carbon martensitic steels and cast medium-carbon martensitic steels respectively). An impeller is a rotor inside a tube or conduit to increase the pressure and flow of a fluid The term volute is used in a number of different contexts all of which derive from and allude to the original Latin root word voluta ("scroll" In A rolling-element bearing is a bearing which carries a load by placing round elements between the two pieces A backhoe, also called a rear actor or back actor, is a piece of excavating equipment consisting of a digging bucket on the end of a two-part articulated arm

It is difficult to cool thick castings fast enough to solidify the melt as white cast iron all the way through. However, rapid cooling can be used to solidify a shell of white cast iron, after which the remainder cools more slowly to form a core of grey cast iron. The resulting casting, called a “chilled casting”, has the benefits of a hard surface and a somewhat tougher interior.

White cast iron can also be made by using a high percentage of chromium in the iron; Cr is a strong carbide-forming element, so at high enough percentages of chrome, the precipitation of graphite out of the iron is suppressed. Chromium (ˈkroʊmiəm is a Chemical element which has the symbol Cr and Atomic number 24 High-chrome white iron alloys allow massive castings (for example, a 10-tonne impeller) to be sand cast, i. e. , a high cooling rate is not required, as well as providing impressive abrasion resistance.

Malleable iron starts as a white iron casting, that is then heat treated at about 900 °C. Malleable iron is the oldest member of the family of Nodular irons Like all nodular irons malleable iron exhibits good Ductility. Second Album by Rock and roll Singer-songwriter near-legend Graham Parker. Graphite separates out much more slowly in this case, so that surface tension has time to form it into spheroidal particles rather than flakes. For the work of fiction see Surface Tension (short story. Surface tension is a property of the surface of a Liquid that causes it to Due to their lower aspect ratio, spheroids are relatively short and far from one another, and have a lower cross section vis-a-vis a propagating crack or phonon. The aspect ratio of a Shape is the ratio of its longer Dimension to its shorter dimension In Geometry, a cross section is the intersection of a body in 2-dimensional space with a line or of a body in 3-dimensional space with a plane etc They also have blunt boundaries, as opposed to flakes, which alleviates the stress concentration problems faced by grey cast iron. In general, the properties of malleable cast iron are more like mild steel. There is a limit to how large a part can be cast in malleable iron, since it is made from white cast iron.

A more recent development is nodular or ductile cast iron. Ductile iron, also called ductile cast iron, spheroidal graphite iron, or nodular cast iron, is a type of Cast iron invented in 1943 by Tiny amounts of magnesium or cerium added to these alloys slow down the growth of graphite precipitates by bonding to the edges of the graphite planes. Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Cerium (ˈsɪəriəm is a Chemical element with the symbol Ce and Atomic number 58 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.

Historical uses

A cast iron wagon wheel

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 first invented in China (see also: Du Shi), and poured into molds to make weapons and figurines. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Du Shi ( d 38 was a Chinese governmental Prefect of Nanyang in 31 AD and a mechanical Engineer of the Eastern Han Dynasty in Ancient Historically, its earliest uses included cannon and shot. In England, the ironmasters of the Weald continued producing these until the 1760s, and this was the main function of the iron industry there after the Restoration, though probably only a minor part of the industry there earlier. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland An ironmaster is the manager &ndash and usually owner &ndash of a Forge or Blast furnace for the processing of Iron. The Weald (wɪəld is the name given to a physiographic area in south-east England situated between the parallel Chalk Escarpments of the North Events and Trends King George III ascends the British throne in 1760. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 The English Restoration, or simply The Restoration began in 1660 when the English monarchy, Scottish monarchy and Irish monarchy were restored

Cast iron pots were made at many English blast furnaces at that period. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland A blast furnace is a type of metallurgical Furnace used for Smelting to produce metals generally Iron. In 1707, Abraham Darby patented a method of making pots (and kettles) thinner and hence cheaper than his rivals could. Abraham Darby ( April 14, 1678 &ndash May 5, 1717) was the first and most famous of three generations with that name in an 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. Coalbrookdale is a side valley of the Ironbridge Gorge in the borough of Telford and Wrekin and ceremonial county of Shropshire, England Events and trends Manufacture of the earliest surviving Pianos World leaders Louis XV King of France Events and trends The Great Awakening - A Protestant religious movement active in the British colonies of North America Coke is a solid Carbonaceous material derived from Destructive distillation of low-ash low-sulfur Bituminous coal.

The development of the steam engine by Thomas Newcomen provided a further market for cast iron, since this was considerably cheaper than the brass of which the engine cylinders were originally made. The atmospheric engine invented by Thomas Newcomen in 1712 today referred to as a Newcomen steam engine (or simply Newcomen engine was the first practical Thomas Newcomen (born shortly before 24 February 1664; died 5 August 1729) was an Ironmonger by trade and a Baptist Brass is any Alloy of Copper and Zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties A great exponent of cast iron was John Wilkinson, who amongst other things cast the cylinders for many of James Watt's improved steam engines until the establishment of the Soho Foundry in 1795. John "Iron-Mad" Wilkinson (1728 &ndash 1808 was an English Industrialist who suggested the use of Cast iron for many roles where other James Watt ( 19 January 1736 &ndash 25 August 1819 Boulton proved to be an excellent businessman and both men eventually made fortunes The Watt steam engine was the first type of Steam engine to make use of steam at a pressure just above atmospheric to drive the piston helped by a partial vacuum Soho Foundry (not to be confused with the Soho Manufactory) was a Factory created in 1795 by Matthew Boulton and James Watt at Smethwick Year 1795 ( MDCCXCV) was a Common year starting on Thursday (link will display the full calendar of the Gregorian calendar (or a

Cast iron bridges

The Eglinton Tournament Bridge, built from cast iron. The Eglinton Tournament Bridge is a Bridge located within Eglinton Country Park near Kilwinning, North Ayrshire, Scotland.

The major use of cast iron for structural purposes began in the late 1770s when Abraham Darby III built the Iron Bridge, although short beams had been used prior to the bridge, such as in the blast furnaces at Coalbrookdale. Events and trends For more events see 18th century United States Declaration of Independence ratified by the Continental Congress Abraham Darby III (1750 &ndash 1791 was an English Ironmaster and Quaker. The Iron Bridge crosses the River Severn at the Ironbridge Gorge, by the village of Ironbridge, in Shropshire, England. This was followed by others, including Thomas Paine, who patented one; cast iron bridges became common as the Industrial Revolution gathered pace. Thomas Paine (January 29 1737 &ndash June 8 1809 was an English Pamphleteer, Revolutionary, radical, Inventor, and Intellectual The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture manufacturing and transportation had a profound effect on the Thomas Telford adopted the material for his bridge upstream at Buildwas, and then for a canal trough aqueduct at Longdon-on-Tern on the Shrewsbury Canal. Thomas Telford (9 August 1757 - 2 September 1834 was born in Westerkirk, Scotland. Buildwas is a village ruled by fin and a parish in Shropshire, England, on the north bank of the River Severn at. Longdon-on-Tern (also known as Longdon-upon-Tern or colloquially Longdon) is a village in east central Shropshire, England, situated approximately The Shrewsbury Canal (or Shrewsbury and Newport Canal) was a Canal in Shropshire, England. It was followed by the spectacular Chirk Aqueduct and the breath-taking Pontcysyllte Aqueduct, both of which remain in use following recent restorations. Chirk Aqueduct is a 70ft high and 710ft long Aqueduct near Chirk that carries the Llangollen Canal across the Ceiriog Valley. The Pontcysyllte Aqueduct ˌpɔntkəˈsʌɬtɛ (and approximately pronounced "pont-kuss-uth-tay" is a navigable Aqueduct that carries the Llangollen Canal Cast iron beam bridges were used widely by the early railways, such as the Water street bridge at the Manchester terminus of the Liverpool and Manchester Railway. The Liverpool and Manchester Railway (L&MR was the world's first inter-city passenger Railway in which all the trains were timetabled and were hauled for most of the distance However, problems arose when such a bridge collapsed shortly after opening in 1846. The Dee bridge disaster was caused by excessive loading at the centre of the beam by a passing train, and many similar bridges had to be demolished and rebuilt, often in wrought iron. The Dee bridge disaster was an English Rail accident that occurred on 24 May 1847 with five fatalities QtubIronPillarJPG|thumb|right| Iron pillar at Delhi India containing 98% wrought iron]] Wrought iron is commercially pure Iron. The bridge had been under-designed, being trussed with wrought iron straps, which were wrongly thought to reinforce the structure. Nevertheless, cast iron continued to be used for structural support, until the Tay Rail Bridge disaster of 1879 created a crisis of confidence in the material. The Tay Bridge (sometimes unofficially the Tay Rail Bridge) is a Railway Bridge approximately two and a quarter miles (three and a half kilometres Further bridge collapses occurred, however, culminating in the Norwood Junction rail accident of 1891. The Norwood Junction railway crash occurred on 1 May 1891, when a Cast iron under-bridge fractured under an Express train from Brighton Thousands of cast iron rail under-bridges were eventually replaced by steel equivalents.

Textile mills

Another important use was in textile mills. The air in these contained flammable fibres from the cotton, hemp, or wool being spun. Cotton is a soft staple Fibre that grows around the seeds of the cotton plant ( Gossypium sp This article is about the cultivation and uses of industrial hemp not its psychoactive cousin Cannabis (drug. Wool is the fiber derived from the specialized skin cells called follicles of animals in the Caprinae family principally sheep, but the hair of certain species As a result, textile mills had an alarming propensity to burn down. The solution was to build them completely of non-combustible materials, and it was found convenient to provide the building with an iron frame, largely of cast iron. This replaced flammable wood. The first such building was at Ditherington in Shrewsbury, Shropshire. Ditherington is a district within the town of Shrewsbury, county town of Shropshire, England. Shrewsbury ( /ˈʃruːzbri/ or /ˈʃroʊzbri/ is the County town of Shropshire, in the West Midlands region of England Shropshire (ˈʃrɒpʃɪə/ /-ʃə alternatively known as Salop or abbreviated in print only Shrops, is a county in the Many other warehouses were built using cast iron columns and beams, although there were many collapses owing to faulty designs, flawed beams or overloading.

During the Industrial Revolution, cast iron was also widely used for the frame and other fixed parts of machinery, including spinning and later weaving machinery in the textile mills. The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture manufacturing and transportation had a profound effect on the Cast iron became a widespread material, and many towns had foundries producing machinery, not only for industry but also agriculture. A foundry is a Factory which produces Metal Castings from either Ferrous or non-ferrous alloys Agriculture refers to the production of goods through the growing of plants and fungi and the raising of domesticated Animals The study of agriculture

See also

• Cast-iron architecture
• Cast iron cookware
• Mechanical bank
• Sand casting

References

• John Gloag and Derek Bridgwater, A History of Cast Iron in Architecture, Allen and Unwin, London (1948)
• Peter R Lewis, Beautiful Railway Bridge of the Silvery Tay: Reinvestigating the Tay Bridge Disaster of 1879, Tempus (2004) ISBN 07524 3160 9
• Peter R Lewis, Disaster on the Dee: Robert Stephenson's Nemesis of 1847, Tempus (2007) ISBN 0 7524 4266 2
• George Laird, Richard Gundlach and Klaus Röhrig, Abrasion-Resistant Cast Iron Handbook, ASM International (2000) ISBN 0-87433-224-9

External links

• Metallurgy of Cast Irons, Cambridge University
• Paper on the Tay bridge disaster