A wrought iron railing in Troy, New York.

Wrought iron is commercially pure iron, having a very small carbon content (not more than 0.15 percent), but usually containing some slag. It is tough, malleable and ductile and is easily welded. However, it is too soft for blades. Image File history File linksMetadata Download high resolution version (2272x1704, 819 KB) Summary A railing in Troy, NY. Licensing File links The following pages link to this file: Wrought iron Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. ... Image File history File linksMetadata Download high resolution version (2272x1704, 819 KB) Summary A railing in Troy, NY. Licensing File links The following pages link to this file: Wrought iron Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. ... Guard rail, sometimes referred to as guide rail, is a system designed to keep people or vehicles from (in most cases unintentionally) straying into dangerous or off-limits areas. ... Looking west down Broadway at downtown Troy. ... For other uses, see Iron (disambiguation). ... For other uses, see Carbon (disambiguation). ... Slag is also an early play by David Hare. ... Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ...

Terminology

Wrought iron is so named because it is worked from a "bloom" of porous iron mixed with slag and other impurities. The word "wrought" is an archaic past tense of the verb to work. As irregular past-tense forms in English have historically been phased out over long periods of time, wrought became worked. Wrought iron literally means worked iron. Look up bloom in Wiktionary, the free dictionary. ...

When consumers look for wrought iron goods they may also refer to them as rod iron or rot iron. The term also could mean the consumer is looking for one of three different possibilities: actual wrought iron items, hand forged items, or simply the "look" of wrought iron. Even though the official term is wrought iron, the other variations have become commonplace.

Overview

Wrought iron has been used for thousands of years, and represents the "iron" that is referred to throughout western history. It is a fibrous material with many strands of slag mixed into the metal. These slag inclusions give it a "grain" resembling wood, with distinct appearance when etched or bent to the point of failure. In mineralogy, an inclusion is any material that is trapped inside a mineral during its formation. ...

Wrought iron has been almost totally replaced by mild steel. It is not produced at all today for commercial use, although one company in the U.K. is known to reprocess scrap, antique wrought iron into stock for commercial sale. It was used when a tough material was required, in applications such as rivets, chains, railway couplings, water and steam pipes, raw material for manufacturing of steel, bolts and nuts, horse shoe bars, handrails, straps for timber roof trusses, boiler tubes, etc. References relating to wrought iron may occasionally still be found in engineering literature. Plain-carbon steel is a metal alloy, a combination of two elements, iron and carbon, where other elements are present in quantities too small to affect the properties. ... A rivetted buffer beam on a steam locomotive A rivet is a mechanical fastener consisting of a smooth cylindrical shaft with heads on either end. ... Look up chain in Wiktionary, the free dictionary. ... Knuckle (AAR Type E) couplers in use AAR Type E railroad car coupling A coupling (or a coupler) is a mechanism for connecting railway cars in a train. ... A system of copper water tubes used in a radiator heating system. ... For other uses, see Steam (disambiguation). ... A bolt may be one of the following things: For bolts and capscrews, see Bolted joint. ... A nut is a type of hardware fastener with a threaded hole. ... Modern horseshoes are most commonly made of iron and nailed onto the hoof. ... This page is a candidate to be moved to Wiktionary. ... In architecture and structural engineering, a truss is a static structure consisting of straight slender members inter-connected at joints into triangular units. ...

Ornamental ironwork utilises the great malleability of wrought iron, and is still often referred to as "wrought iron work" even though today it is more likely to be made from mild steel Gate of the Winter Palace in St Petersburg. ...

History

Bloomery process

Wrought iron was originally produced by a variety of smelters, described today as bloomeries. A number of different forms of bloomery were used at different places and times. The bloomery would be charged with charcoal and iron ore (an oxide or carbonate) and lit. Air was blown in through a tuyere to heat the bloomery to a temperature somewhat below the melting point of iron. In the course of the smelt, slag would melt and run out, and carbon monoxide from the charcoal would reduce the ore to iron, which formed a spongy mass. The iron remained in the solid state. If the bloomery was allowed to become hot enough to melt the iron, carbon would dissolve into it and form "pig" or "cast" iron, but that was not the intention. A bloomery is a type of furnace once widely used for smelting iron from its oxides. ... Charcoal is the blackish residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances. ... An oxide is a chemical compound containing an oxygen atom and other elements. ... Ball-and-stick model of the carbonate ion, CO32− For other meanings, see Carbonate (disambiguation) In chemistry, a carbonate is a salt or ester of carbonic acid. ... A blacksmiths forge For finery forges (making iron) see finery forge. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ...

After smelting was complete, the bloom was removed, and the process can be started again. It is thus a batch process, rather than a continuous one. The spongy mass contains iron and also silicate (slag) from the ore; this is iron bloom from which the technique gets its name. The bloom then has to be forged mechanically to consolidate it and shape it into a bar, expelling slag in the process. Iron bloom (in German Eisenblüte) is a mixture of fine iron particles, unreacted iron oxide (ore), slag and charcoal residue. ...

During the Middle Ages, water-power was applied to the process, probably initially for powering bellows, and only later to hammers for forging the blooms. However, while it is certain that water-power was used, the details of this remain uncertain. This was the culmination of the direct process of ironmaking. It survived in Spain and southern France as Catalan Forges to the mid 19th century, in Austria as the stuckofen to 1775; near Garstang in England until about 1770; and was still in use with hot blast in New York State in the 1880s. The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... Garstang is a small town in the county of Lancashire in the North of England, located within the borough of Wyre. ... For the village in Queensland, see 1770, Queensland. ... Hot Blast refers to the air blown into a blast furnace or other metallurgical process being preheated. ... State nickname: Empire State Other U.S. States Capital Albany Largest city New York Governor George Pataki Official languages None Area 141,205 km² (27th)  - Land 122,409 km²  - Water 18,795 km² (13. ... // Development and commercial production of electric lighting Development and commercial production of gasoline-powered automobile by Karl Benz, Gottlieb Daimler and Maybach First commercial production and sales of phonographs and phonograph recordings. ...

Indirect processes

The direct process was largely replaced during the Middle Ages with an indirect smelting process, involving a blast furnace and then one of a succession of further processes, including the finery forge, and later the puddling furnace. The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... Smelting rhymes with melting Electric phosphate smelting furnace in a TVA chemical plant (1942) Chemical reduction, or smelting, is a form of extractive metallurgy. ... Blast furnace in Sestao, Spain. ... Iron tapped from the blast furnace is pig iron, and contains significant amounts of carbon and silicon. ... Schematic drawing of a puddling furnace The puddling furnace is a metalmaking technology to create wrought iron from the pig iron produced in a blast furnace. ...

Examples of the blast furnace have been discovered from the Middle Ages at Lapphyttan, Sweden and in Germany. This was combined with a further process making osmond iron, balls of wrought iron. The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... Lapphyttan in Sweden may be regarded as the type site for the Medieval Blast Furnace. ... Osmond iron (also spelt osmund and also called osborn) was wrought iron made by a particular process. ...

In the 15th century, the blast furnace spread into what is now Belgium and was improved. From there, it spread via the pays de Bray on the boundary of Normandy and then to the Weald in England. The product of a blast furnace, pig iron, had a high carbon content and was brittle. In order to use it in ironmongery, this had to be converted to wrought iron. This was the function of the finery forge and successor processes. These remelted the pig iron and (in effect) burnt out the carbon, producing a bloom, which was then forged into a bar. If rod iron was required a slitting mill was used. (14th century - 15th century - 16th century - other centuries) As a means of recording the passage of time, the 15th century was that century which lasted from 1401 to 1500. ... For other uses, see Normandy (disambiguation). ... A weald once meant a dense forest, especially the famous great wood once stretching far beyond the ancient counties of Sussex and Kent, England, where this country of smaller woods is still called the Weald. ... For other uses, see England (disambiguation). ... Two weights used in the theatre and made of pig iron; because of this, they are dubbed pig weights or simply pigs. ... Iron tapped from the blast furnace is pig iron, and contains significant amounts of carbon and silicon. ... A wrought iron railing in Troy, New York. ... A wrought iron railing in Troy, New York. ... The Slitting Mill was a water-powered mill for slitting bars of iron into rods. ...

The introduction of coke for use in the blast furnace by Abraham Darby in 1709 (or perhaps others a littler earlier) changed ironmaking and eventually replaced charcoal. Not only was the fuel much cheaper, but it is also less friable, allowing the furnaces to be much larger. However, charcoal continued to be the fuel for the finery. Coke Coke is a solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. ... Blast furnace in Sestao, Spain. ... Abraham Darby (c. ... // Events January 12 - Two-month freezing period begins in France - The coast of the Atlantic and Seine River freeze, crops fail and at least 24. ...

Puddling and faggoting

The puddling process of smelting iron ore to make wrought iron from pig iron, the right half of the illustration (not shown) displays men working a blast furnace, Tiangong Kaiwu encyclopedia published in 1637, written by Song Yingxing (1587-1666).

A number of processes for making wrought iron without charcoal were devised as the Industrial Revolution began during the latter half of the 18th century. The most successful of these was the puddling furnace invented by Henry Cort in 1784. The fully developed process involved a series of stages. First the iron was melted in a "refinery" or "running out fire". The iron was run out into a trough whose dam was lowered enough to run off the slag, thus reducing the silicon content. This produced a brittle white metal ("finers metal"), which was charged to the puddling furnace, where it was melted and stirred. The resultant puddled ball was "shingled" with a hammer and then rolled in a rolling mill to produce "muck bar". This would be broken up and faggotted. Wrought iron which had been faggoted twice was referred to as "Best"; if faggoted again it would become "Best Best", then "Treble best", etc. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... For other uses, see Iron (disambiguation). ... Iron ore (Banded iron formation) Manganese ore Lead ore Gold ore An ore is a volume of rock containing components or minerals in a mode of occurrence which renders it valuable for mining. ... Two weights used in the theatre and made of pig iron; because of this, they are dubbed pig weights or simply pigs. ... Blast furnace in Sestao, Spain. ... “Cyclopedia” redirects here. ... Song Yingxing (Traditional Chinese:宋應星; Simplified Chinese:宋应星; Wade Giles: Sung Ying-Hsing; 1587-1666 AD) was a Chinese scientist and encyclopedist who lived during the late Ming Dynasty (1368-1644). ... 1587 was a common year starting on Thursday of the Gregorian calendar (or a common year starting on Sunday of the 10-day slower Julian calendar). ... 1666 is often called Annus Mirabilis. ... Charcoal is the blackish residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances. ... A Watt steam engine, the steam engine that propelled the Industrial Revolution in Britain and the world. ... (17th century - 18th century - 19th century - more centuries) As a means of recording the passage of time, the 18th century refers to the century that lasted from 1701 through 1800. ... Schematic drawing of a puddling furnace The puddling furnace is a metalmaking technology to create wrought iron from the pig iron produced in a blast furnace. ... Henry Cort is a good guy(1740 – 1800) was an English ironmaster. ... 1784 was a leap year starting on Thursday (see link for calendar). ... Shingling was a stage in the production of bar iron or steel, in the finery and puddling processes. ... Faggoting or faggoting and folding is a metalworking technique used in the smelting and forging of wrought iron, damascus steel, and other steel. ...

Faggoting resulted in impurities within the metal ending up as long thin inclusions, creating a grain within the metal. "Best" bars would have a tensile strength along the grain of about 23 short tons-force per square inch (317 MPa). "Treble best" could reach 28 short tons-force per square inch (386 MPa). The strengths across the grain would be about 15% lower. This grain makes wrought iron especially tricky to smith, as it behaves much like wood grain—prone to spontaneous splitting along the grain. In old, very rusted pieces of wrought iron, the grain is revealed, making the iron bear a striking resemblance to reddish-brown wood. Faggoting or faggoting and folding is a metalworking technique used in the smelting and forging of wrought iron, damascus steel, and other steel. ... Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ... The short ton is a unit of mass equal to 907. ...

Aston's process

In 1925, James Aston of the United States developed a wholly mechanical process for manufacturing wrought iron quickly and economically. It is carried out as follows: Year 1925 (MCMXXV) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar. ...

1. Molten steel from a Bessemer converter is poured into cooler liquid slag. Temperature of molten steel is about 1500 °C and that of liquid slag is about 1200 °C.
2. Molten steel contains large amounts of dissolved gases. These gases are liberated when it strikes the slag.
3. Molten steel freezes to yield a spongy mass having a temperature of about 1370 °C.
4. This spongy mass is then shingled and rolled as described below.

The Bessemer process was the first inexpensive industrial process for the mass-production of steel from a molten pig iron. ... Shingling was a stage in the production of bar iron or steel, in the finery and puddling processes. ... A wrought iron railing in Troy, New York. ...

Modern production

Wrought iron is relatively pure, and normally contains less than .15% carbon and other impurities. But the process of its manufacture is laborious and tedious. Following are the four distinct operations involved in its manufacture:

1. Refining
2. Puddling
3. Shingling
4. Rolling

Refining

Pig iron is melted and a strong current of air is directed over it. It is being well agitated or stirred when the current of air is passing over. Impurities (such as silicon) are thus thoroughly oxidized. The metal is then cast into moulds. It is cooled suddenly, making it brittle. This is known as refined pig iron. It has also been known as finers metal and as refined iron.

Puddling

Main article: Puddling (metallurgy)

Conversion of pig iron into wrought iron by stirring in a molten state is known as puddling. It is carried out in a reverberatory furnace. In this type of furnace, the metal does not come into contact with the fuel, and flame from the fire is reverted or sent back on the metal in the hearth. Schematic drawing of a puddling furnace Puddling was an Industrial Revolution means of making iron and steel. ... Schematic drawing of a puddling furnace The puddling furnace is a metalmaking technology to create wrought iron from the pig iron produced in a blast furnace. ... A reverbatory furnace is a metallurgical or process furnace which characteristically isolates the material being processed from contact with the fuel, but not from contact with the combustion gases. ...

A reverberatory furnace, which is of rectangular shape, is built with refractory materials such as firebricks. The combustion chamber and the chimney are situated at opposite ends. Grating is provided in the combustion chamber to collect ash in an ash pit. Next to the combustion chamber is the hearth portion with shallow depth. Hearth lining consists of molten slag or rich iron ore. It is supported on steel plates, which in turn are supported on dwarf brick walls. Water jackets are provided for circulation of water to cool the furnace. Various doors or openings for fuel feeding, working and slag removal are provided. The roof is given a peculiar shape so that flames of gas produced are concentrated on hearth.

The refined pig iron is broken into lumps and is melted in the hearth of the reverberatory furnace. The hearth lining acts as an oxidizing agent and, in addition, oxidizing substances such as haematite ore, oxide of iron, etc., are added to the refined pig iron. It is subjected to intense heat and a strong current of air. It is kept well stirred by long bars through working doors.

During the process of puddling, most of the carbon content and other impurities of the pig iron are oxidized. Slag formed is removed through a slag removal door. The purified iron becomes thick and assumes the form of white spongy iron balls, known as puddle balls, the weight of which is about 50 to 70 kg.

Shingling

Main article: Shingling (metallurgy)

By this operation, the slag contained is removed. It may be achieved by forging the balls under a power hammer or by passing the balls through a squeezing machine. In the case of the power hammer, the balls are placed on an anvil and a falling hammer forges them. A squeezing machine consists of two cylinders, which are placed one inside the other. The smaller cylinder has corrugations on its outer surface and the larger cylinder has corrugations on its inner surface. The balls are placed in between the cylinders and then the inner cylinder is rotated. Shingling was a stage in the production of bar iron or steel, in the finery and puddling processes. ...

Shingling also helps in binding or welding the particles of puddle balls. The material obtained at the end of shingling is known as bloom and it is still in red-hot condition.

Rolling

Main article: Rolling mill

The bloom is passed through grooved rollers and flat bars of sizes such as about 4 m × 10 cm × 25 mm are obtained. These bars of wrought iron of poor quality are called muck bars. To improve the quality of wrought iron, these bars are tied together by wires, a process known as faggoting and they are heated and rolled again. This process may be repeated several times to get wrought iron of desired quality. A rolling mill is a machine or factory for shaping metal by passing it between rollers. ... A wrought iron railing in Troy, New York. ... Faggoting or faggoting and folding is a metalworking technique used in the smelting and forging of wrought iron, damascus steel, and other steel. ...

Properties

The fibers in wrought iron give it properties not found in other forms of ferrous metal. Hammering a piece of wrought iron cold causes the fibers to become packed tighter, which makes the iron both brittle and hard. 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. Furthermore, wrought iron cannot be bent as sharply as steel, for the fibers can spread and weaken the finished work. Heat treatment is a method used to alter the physical, and sometimes chemical, properties of a material. ... Cold iron is an archaic term for wrought iron that is hammered without heating in order to compress the metals fibers, thus hardening the metal. ...

Other properties of wrought iron include the following:

• It becomes soft at red heat and it can be easily forged and welded.
• It can be used to form temporary magnets, but cannot be magnetized permanently.
• It fuses with difficulty. It cannot, therefore, be adopted for making castings.
• It is ductile, malleable and tough.
• It is moderately elastic.
• It is less affected by saline water than steel, and resists corrosion better.
• Its fresh fracture shows clear bluish colour with a high silky luster and fibrous appearance.
• Its melting point is about 1500 °C.
• Its specific gravity is about 7.8.
• Its ultimate compressive strength is about 2000 kgf/cm² (200 MPa).
• Its ultimate tensile strength is about 4000 kgf/cm² (400 MPa).

This article is about smithing. ... Welding is a joining process that produces coalescence of materials (typically metals or thermoplastics) by heating them to welding temperature, with or without the application of pressure or by the application of pressure alone, and with or without the use of filler material. ... For other uses, see Magnet (disambiguation). ... This article is about the manufacturing process. ... Ductility is the physical property of being capable of sustaining large plastic deformations without fracture (in metals, such as being drawn into a wire). ... Malleability is a physical property of matter, signifying its capability of deformation, especially by hammering or rolling. ... In materials science and metallurgy, toughness is the resistance to fracture of a material when stressed. ... Look up elastic in Wiktionary, the free dictionary. ... For the hazard, see corrosive. ... For the meaning of fiber in nutrition, see dietary fiber. ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Compressive strength is the capacity of a material to withstand axially directed pushing forces. ... A kilogram-force per square centimeter (kgf/cm2), often just kilogram per square centimeter (kg/cm2), is a unit of pressure using metric units. ... The megapascal, symbol MPa is an SI unit of pressure. ... Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ...

Defects

Wrought iron is defective in quality if it is either coldshort or redshort.

Coldshort

Coldshort (or "bloodshot") wrought iron occurs when phosphorus is present in excess quantity and is very brittle when it is cold. It cracks if bent. It may, however, be worked at high temperature. Historically, coldshort iron was considered good enough for nails. A pile of nails. ...

Redshort

Redshort wrought iron possesses sulphur in excess quantity. It has sufficient tenacity when cold, but cracks when bent or finished at a red heat. It is therefore useless for welding or forging.

Structural Material

Wrought iron was used throughout the 18th and 19th centuries for rails, chain links, and rivets, or pretty much any structural member requiring high tensile strength in one direction. The RMS Titanic was partially constructed using wrought iron rivets, whose quality may have played a role in her rapid sinking. (Hooper McCarty and Foecke, 'What Really Sank the Titanic:New Forensic Discoveries", Citadel Press, 2008, ISBN 0806528958) For other uses, see Titanic (disambiguation). ... A rivetted buffer beam on a steam locomotive A rivet is a mechanical fastener consisting of a smooth cylindrical shaft with heads on either end. ...

See also

• Pig iron
• Ornamental metal
• Wrought iron furniture
• Iron rod
• Cold iron

Two weights used in the theatre and made of pig iron; because of this, they are dubbed pig weights or simply pigs. ... This particular machine stands over 6 ft (1. ... It has been suggested that this article or section be merged into Wrought iron. ... Iron rod is a type of wrought iron and is used in building and heavy construction, specially in armed concrete. ... Cold iron is an archaic term for wrought iron that is hammered without heating in order to compress the metals fibers, thus hardening the metal. ...

References

• Bealer, Alex W. (1995). The Art of Blacksmithing. Edison, NJ: Castle Books, 28-45. ISBN 0785803955. 

External links

• Clearing the Confusion Over Wrought Iron - National Ornamental & Miscellaneous Metals Association
• The Wrought Iron Advisory Centre - Commercial site.
• Forensic Studies of the Titanic's wrought iron rivets - Jennifer Hooper McCarty and Tim Foecke
• Wrought Iron in Croatia - Commercial site