Obermarsberg is one of seventeen quarters in the municipality of Marsberg , North Rhine-Westphalia , Germany . It is situated on the site of an Old Saxon hillfort and refuge castle , the Eresburg , on a hill 130m above the Diemel river, a tributary of the River Weser .
115-726: The location was originally the site of an Iron Age hillfort , founded probably sometime before or during the era of the Roman-Germanic wars ; including the Battle of the Teutoburg Forest (circa AD 9) and the Battle of the Weser River (circa AD 16). Although it is unclear whether the surrounding area was controlled by the Cherusci , Chatti , or perhaps Marsi (as described by Tacitus ), no particular reference to
230-412: A BOS process is manufactured in one-twelfth the time. Today, electric arc furnaces (EAF) are a common method of reprocessing scrap metal to create new steel. They can also be used for converting pig iron to steel, but they use a lot of electrical energy (about 440 kWh per metric ton), and are thus generally only economical when there is a plentiful supply of cheap electricity. The steel industry
345-526: A Celtiberian stronghold against Roman invasions. İt dates more than 2500 years back. The site was researched by Francisco Martins Sarmento starting from 1874. A number of amphoras (containers usually for wine or olive oil), coins, fragments of pottery, weapons, pieces of jewelry, as well as ruins of a bath and its pedra formosa ( lit. ' handsome stone ' ) revealed here. The Iron Age in Central Asia began when iron objects appear among
460-531: A brittle alloy commonly called pig iron . 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 , sulphur , silicon , and traces of oxygen , nitrogen , and copper . Plain carbon-iron alloys with
575-713: A carbon-intermediate steel by the 1st century AD. There is evidence that carbon steel was made in Western Tanzania by the ancestors of the Haya people as early as 2,000 years ago by a complex process of "pre-heating" allowing temperatures inside a furnace to reach 1300 to 1400 °C. Evidence of the earliest production of high carbon steel in South Asia is found in Kodumanal in Tamil Nadu ,
690-444: A change of volume. In this case, expansion occurs. Internal stresses from this expansion generally take the form of compression on the crystals of martensite and tension on the remaining ferrite, with a fair amount of shear on both constituents. If quenching is done improperly, the internal stresses can cause a part to shatter as it cools. At the very least, they cause internal work hardening and other microscopic imperfections. It
805-699: A combination of bivalve moulds of distinct southern tradition and the incorporation of piece mould technology from the Zhongyuan . The products of the combination of these two periods are bells, vessels, weapons and ornaments, and the sophisticated cast. An Iron Age culture of the Tibetan Plateau has been associated tentatively with the Zhang Zhung culture described by early Tibetan writings. In Japan, iron items, such as tools, weapons, and decorative objects, are postulated to have entered Japan during
920-428: A ferrite BCC crystal form, but at higher carbon content it takes a body-centred tetragonal (BCT) structure. There is no thermal activation energy for the transformation from austenite to martensite. There is no compositional change so the atoms generally retain their same neighbours. Martensite has a lower density (it expands during the cooling) than does austenite, so that the transformation between them results in
1035-583: A hard oxide forms on the metal surface; this is known as stainless steel . Tungsten slows the formation of cementite , keeping carbon in the iron matrix and allowing martensite to preferentially form at slower quench rates, resulting in high-speed steel . The addition of lead and sulphur decrease grain size, thereby making the steel easier to turn , but also more brittle and prone to corrosion. Such alloys are nevertheless frequently used for components such as nuts, bolts, and washers in applications where toughness and corrosion resistance are not paramount. For
1150-445: A hard but brittle martensitic structure. The steel is then tempered, which is just a specialized type of annealing, to reduce brittleness. In this application the annealing (tempering) process transforms some of the martensite into cementite, or spheroidite and hence it reduces the internal stresses and defects. The result is a more ductile and fracture-resistant steel. When iron is smelted from its ore, it contains more carbon than
1265-434: A higher than 2.1% carbon content are known as cast iron . With modern steelmaking techniques such as powder metal forming, it is possible to make very high-carbon (and other alloy material) steels, but such are not common. Cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties. Certain compositions of cast iron, while retaining
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#17327757932321380-412: A narrow range of concentrations of mixtures of carbon and iron that make steel, several different metallurgical structures, with very different properties can form. Understanding such properties is essential to making quality steel. At room temperature , the most stable form of pure iron is the body-centred cubic (BCC) structure called alpha iron or α-iron. It is a fairly soft metal that can dissolve only
1495-534: A small concentration of carbon, no more than 0.005% at 0 °C (32 °F) and 0.021 wt% at 723 °C (1,333 °F). The inclusion of carbon in alpha iron is called ferrite . At 910 °C, pure iron transforms into a face-centred cubic (FCC) structure, called gamma iron or γ-iron. The inclusion of carbon in gamma iron is called austenite. The more open FCC structure of austenite can dissolve considerably more carbon, as much as 2.1%, (38 times that of ferrite) carbon at 1,148 °C (2,098 °F), which reflects
1610-453: A steel's final rolling, it is heat treated for strength; however, this is relatively rare. Steel was known in antiquity and was produced in bloomeries and crucibles . The earliest known production of steel is seen in pieces of ironware excavated from an archaeological site in Anatolia ( Kaman-Kalehöyük ) which are nearly 4,000 years old, dating from 1800 BC. Wootz steel
1725-477: A subsequent step. Other materials are often added to the iron/carbon mixture to produce steel with the desired properties. Nickel and manganese in steel add to its tensile strength and make the austenite form of the iron-carbon solution more stable, chromium increases hardness and melting temperature, and vanadium also increases hardness while making it less prone to metal fatigue . To inhibit corrosion, at least 11% chromium can be added to steel so that
1840-588: A tower, the crumbling remains of which can still be seen. Around AD 800 the first Christian church was constructed in Eresburg proper. Although the current church in Obermarsberg only dates to the 13th century, it is at least the second or third church to be built over the remains of Charlemagne 's original church. 51°28′N 8°51′E / 51.467°N 8.850°E / 51.467; 8.850 This Hochsauerlandkreis location article
1955-672: Is continuously cast into long slabs, cut and shaped into bars and extrusions and heat treated to produce a final product. Today, approximately 96% of steel is continuously cast, while only 4% is produced as ingots. The ingots are then heated in a soaking pit and hot rolled into slabs, billets , or blooms . Slabs are hot or cold rolled into sheet metal or plates. Billets are hot or cold rolled into bars, rods, and wire. Blooms are hot or cold rolled into structural steel , such as I-beams and rails . In modern steel mills these processes often occur in one assembly line , with ore coming in and finished steel products coming out. Sometimes after
2070-507: Is a stub . You can help Misplaced Pages by expanding it . Iron Age The Iron Age ( c. 1200 – c. 550 BC ) is the final epoch of the three historical Metal Ages , after the Chalcolithic and Bronze Age . It has also been considered as the final age of the three-age division starting with prehistory (before recorded history) and progressing to protohistory (before written history). In this usage, it
2185-400: Is abundant naturally, temperatures above 1,250 °C (2,280 °F) are required to smelt it, impractical to achieve with the technology available commonly until the end of the second millennium BC. In contrast, the components of bronze—tin with a melting point of 231.9 °C (449.4 °F) and copper with a relatively moderate melting point of 1,085 °C (1,985 °F)—were within
2300-669: Is also speculated that Early Iron Age sites may exist in Kandarodai , Matota, Pilapitiya and Tissamaharama . The earliest undisputed deciphered epigraphy found in the Indian subcontinent are the Edicts of Ashoka of the 3rd century BC, in the Brahmi script . Several inscriptions were thought to be pre-Ashokan by earlier scholars; these include the Piprahwa relic casket inscription,
2415-636: Is also very reusable: it is one of the world's most-recycled materials, with a recycling rate of over 60% globally . The noun steel originates from the Proto-Germanic adjective * * stahliją or * * stakhlijan 'made of steel', which is related to * * stahlaz or * * stahliją 'standing firm'. The carbon content of steel is between 0.02% and 2.14% by weight for plain carbon steel ( iron - carbon alloys ). Too little carbon content leaves (pure) iron quite soft, ductile, and weak. Carbon contents higher than those of steel make
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#17327757932322530-416: Is always the main element in steel, but many other elements may be present or added. Stainless steels , which are resistant to corrosion and oxidation , typically need an additional 11% chromium . Iron is the base metal of steel. Depending on the temperature, it can take two crystalline forms (allotropic forms): body-centred cubic and face-centred cubic . The interaction of the allotropes of iron with
2645-432: Is an alloy of iron and carbon with improved strength and fracture resistance compared to other forms of iron. Because of its high tensile strength and low cost, steel is one of the most commonly manufactured materials in the world. Steel is used in buildings, as concrete reinforcing rods, in bridges, infrastructure, tools, ships, trains, cars, bicycles, machines, electrical appliances, furniture, and weapons. Iron
2760-403: Is common for quench cracks to form when steel is water quenched, although they may not always be visible. There are many types of heat treating processes available to steel. The most common are annealing , quenching , and tempering . Annealing is the process of heating the steel to a sufficiently high temperature to relieve local internal stresses. It does not create a general softening of
2875-536: Is considered to last from c. 1200 BC (the Bronze Age collapse ) to c. 550 BC (or 539 BC ), roughly the beginning of historiography with Herodotus , marking the end of the proto-historical period. In China , because writing was developed first, there is no recognizable prehistoric period characterized by ironworking, and the Bronze Age China transitions almost directly into
2990-403: Is desirable. To become steel, it must be reprocessed to reduce the carbon to the correct amount, at which point other elements can be added. In the past, steel facilities would cast the raw steel product into ingots which would be stored until use in further refinement processes that resulted in the finished product. In modern facilities, the initial product is close to the final composition and
3105-543: Is divided into two periods based on the Hallstatt culture (early Iron Age) and La Tène (late Iron Age) cultures. Material cultures of Hallstatt and La Tène consist of 4 phases (A, B, C, D). The Iron Age in Europe is characterized by an elaboration of designs of weapons, implements, and utensils. These are no longer cast but hammered into shape, and decoration is elaborate and curvilinear rather than simple rectilinear;
3220-405: Is extracted from iron ore by removing the oxygen through its combination with a preferred chemical partner such as carbon which is then lost to the atmosphere as carbon dioxide. This process, known as smelting , was first applied to metals with lower melting points, such as tin , which melts at about 250 °C (482 °F), and copper , which melts at about 1,100 °C (2,010 °F), and
3335-873: Is from Malhar and its surrounding area. This site is assumed as the center for smelted bloomer iron to this area due to its location in the Karamnasa River and Ganga River. This site shows agricultural technology as iron implements sickles, nails, clamps, spearheads, etc., by at least c. 1500 BC. Archaeological excavations in Hyderabad show an Iron Age burial site. The beginning of the 1st millennium BC saw extensive developments in iron metallurgy in India. Technological advancement and mastery of iron metallurgy were achieved during this period of peaceful settlements. One ironworking centre in East India has been dated to
3450-408: Is heat treated to contain both a ferritic and martensitic microstructure to produce a formable, high strength steel. Transformation Induced Plasticity (TRIP) steel involves special alloying and heat treatments to stabilize amounts of austenite at room temperature in normally austenite-free low-alloy ferritic steels. By applying strain, the austenite undergoes a phase transition to martensite without
3565-556: Is likely that the use of ironware made of steel had already begun in the third millennium BC in Central Anatolia". Souckova-Siegolová (2001) shows that iron implements were made in Central Anatolia in very limited quantities about 1800 BC and were in general use by elites, though not by commoners, during the New Hittite Empire (≈1400–1200 BC). Similarly, recent archaeological remains of iron-working in
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3680-691: Is often considered an indicator of economic progress, because of the critical role played by steel in infrastructural and overall economic development . In 1980, there were more than 500,000 U.S. steelworkers. By 2000, the number of steelworkers had fallen to 224,000. The economic boom in China and India caused a massive increase in the demand for steel. Between 2000 and 2005, world steel demand increased by 6%. Since 2000, several Indian and Chinese steel firms have expanded to meet demand, such as Tata Steel (which bought Corus Group in 2007), Baosteel Group and Shagang Group . As of 2017 , though, ArcelorMittal
3795-551: Is one of the world's most-recycled materials, with a recycling rate of over 60% globally; in the United States alone, over 82,000,000 metric tons (81,000,000 long tons; 90,000,000 short tons) were recycled in the year 2008, for an overall recycling rate of 83%. As more steel is produced than is scrapped, the amount of recycled raw materials is about 40% of the total of steel produced - in 2016, 1,628,000,000 tonnes (1.602 × 10 long tons; 1.795 × 10 short tons) of crude steel
3910-713: Is preceded by the Stone Age (subdivided into the Paleolithic , Mesolithic and Neolithic ) and Bronze Age. These concepts originated for describing Iron Age Europe and the Ancient Near East . The indigenous cultures of the New World did not develop an iron economy before 1500 . Although meteoric iron has been used for millennia in many regions, the beginning of the Iron Age is defined locally around
4025-626: Is recorded to extend 10 ha (25 acres) by 800 BC and grew to 50 ha (120 acres) by 700–600 BC to become a town. The skeletal remains of an Early Iron Age chief were excavated in Anaikoddai, Jaffna . The name "Ko Veta" is engraved in Brahmi script on a seal buried with the skeleton and is assigned by the excavators to the 3rd century BC. Ko, meaning "King" in Tamil, is comparable to such names as Ko Atan and Ko Putivira occurring in contemporary Brahmi inscriptions in south India. It
4140-515: Is singularly scarce in collections of Egyptian antiquities. Bronze remained the primary material there until the conquest by the Neo-Assyrian Empire in 671 BC. The explanation of this would seem to be that the relics are in most cases the paraphernalia of tombs, the funeral vessels and vases, and iron being considered an impure metal by the ancient Egyptians it was never used in their manufacture of these or for any religious purposes. It
4255-411: Is the mass production of tools and weapons made not just of found iron, but from smelted steel alloys with an added carbon content. Only with the capability of the production of carbon steel does ferrous metallurgy result in tools or weapons that are harder and lighter than bronze . Smelted iron appears sporadically in the archeological record from the middle Bronze Age . Whilst terrestrial iron
4370-547: Is the world's largest steel producer . In 2005, the British Geological Survey stated China was the top steel producer with about one-third of the world share; Japan , Russia , and the United States were second, third, and fourth, respectively, according to the survey. The large production capacity of steel results also in a significant amount of carbon dioxide emissions inherent related to
4485-483: The 12th century BC (1200–1100 BC). The technology soon spread throughout the Mediterranean Basin region and to South Asia between the 12th and 11th century BC. Its further spread to Central Asia , Eastern Europe , and Central Europe was somewhat delayed, and Northern Europe was not reached until about the start of the 5th century BC (500 BC). The Iron Age in India is stated as beginning with
4600-931: The Badli pillar inscription , the Bhattiprolu relic casket inscription, the Sohgaura copper plate inscription , the Mahasthangarh Brahmi inscription, the Eran coin legend, the Taxila coin legends, and the inscription on the silver coins of Sophytes . However, more recent scholars have dated them to later periods. Dates are approximate; consult particular article for details. Archaeology in Thailand at sites Ban Don Ta Phet and Khao Sam Kaeo yielding metallic, stone, and glass artifacts stylistically associated with
4715-687: The Ganges Valley in India have been dated tentatively to 1800 BC. Tewari (2003) concludes that "knowledge of iron smelting and manufacturing of iron artifacts was well known in the Eastern Vindhyas and iron had been in use in the Central Ganga Plain, at least from the early second millennium BC". By the Middle Bronze Age increasing numbers of smelted iron objects (distinguishable from meteoric iron by
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4830-540: The Geum River basin . The time that iron production begins is the same time that complex chiefdoms of Proto-historic Korea emerged. The complex chiefdoms were the precursors of early states such as Silla , Baekje , Goguryeo , and Gaya Iron ingots were an important mortuary item and indicated the wealth or prestige of the deceased during this period. Dates are approximate; consult particular article for details. The earliest evidence of iron smelting predates
4945-655: The Golconda area in Andhra Pradesh and Karnataka , regions of India , as well as in Samanalawewa and Dehigaha Alakanda, regions of Sri Lanka . This came to be known as wootz steel , produced in South India by about the sixth century BC and exported globally. The steel technology existed prior to 326 BC in the region as they are mentioned in literature of Sangam Tamil , Arabic, and Latin as
5060-727: The Indo-European Saka in present-day Xinjiang (China) between the 10th century BC and the 7th century BC, such as those found at the cemetery site of Chawuhukou. The Pazyryk culture is an Iron Age archaeological culture ( c. 6th to 3rd centuries BC) identified by excavated artifacts and mummified humans found in the Siberian permafrost in the Altay Mountains . Dates are approximate; consult particular article for details. In China, Chinese bronze inscriptions are found around 1200 BC, preceding
5175-730: The Orchid Island . Early evidence for iron technology in Sub-Saharan Africa can be found at sites such as KM2 and KM3 in northwest Tanzania and parts of Nigeria and the Central African Republic. Nubia was one of the relatively few places in Africa to have a sustained Bronze Age along with Egypt and much of the rest of North Africa . Archaeometallurgical scientific knowledge and technological development originated in numerous centers of Africa;
5290-511: The Qin dynasty of imperial China. "Iron Age" in the context of China is used sometimes for the transitional period of c. 900 BC to 100 BC during which ferrous metallurgy was present even if not dominant. The Iron Age in the Ancient Near East is believed to have begun after the discovery of iron smelting and smithing techniques in Anatolia , the Caucasus or Southeast Europe during
5405-528: The Roman conquests of the 1st century BC serve as marking the end of the Iron Age. The Germanic Iron Age of Scandinavia is considered to end c. AD 800 , with the beginning of the Viking Age . The three-age method of Stone, Bronze, and Iron Ages was first used for the archaeology of Europe during the first half of the 19th century, and by the latter half of the 19th century, it had been extended to
5520-589: The Yangtse Valley toward the end of the 6th century BC. The few objects were found at Changsha and Nanjing . The mortuary evidence suggests that the initial use of iron in Lingnan belongs to the mid-to-late Warring States period (from about 350 BC). Important non-precious husi style metal finds include iron tools found at the tomb at Guwei-cun of the 4th century BC. The techniques used in Lingnan are
5635-599: The cementation process was described in a treatise published in Prague in 1574 and was in use in Nuremberg from 1601. A similar process for case hardening armour and files was described in a book published in Naples in 1589. The process was introduced to England in about 1614 and used to produce such steel by Sir Basil Brooke at Coalbrookdale during the 1610s. The raw material for this process were bars of iron. During
5750-419: The hardness , quenching behaviour , need for annealing , tempering behaviour , yield strength , and tensile strength of the resulting steel. The increase in steel's strength compared to pure iron is possible only by reducing iron's ductility. Steel was produced in bloomery furnaces for thousands of years, but its large-scale, industrial use began only after more efficient production methods were devised in
5865-445: The 17th century, it was realized that the best steel came from oregrounds iron of a region north of Stockholm , Sweden. This was still the usual raw material source in the 19th century, almost as long as the process was used. Crucible steel is steel that has been melted in a crucible rather than having been forged , with the result that it is more homogeneous. Most previous furnaces could not reach high enough temperatures to melt
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#17327757932325980-475: The 17th century, the first step in European steel production has been the smelting of iron ore into pig iron in a blast furnace . Originally employing charcoal, modern methods use coke , which has proven more economical. In these processes, pig iron made from raw iron ore was refined (fined) in a finery forge to produce bar iron , which was then used in steel-making. The production of steel by
6095-573: The 17th century, with the introduction of the blast furnace and production of crucible steel . This was followed by the Bessemer process in England in the mid-19th century, and then by the open-hearth furnace . With the invention of the Bessemer process, a new era of mass-produced steel began. Mild steel replaced wrought iron . The German states were the major steel producers in Europe in
6210-481: The 19th century. American steel production was centred in Pittsburgh , Bethlehem, Pennsylvania , and Cleveland until the late 20th century. Currently, world steel production is centered in China, which produced 54% of the world's steel in 2023. Further refinements in the process, such as basic oxygen steelmaking (BOS), largely replaced earlier methods by further lowering the cost of production and increasing
6325-608: The Arabs from Persia, who took it from India. It was originally created from several different materials including various trace elements , apparently ultimately from the writings of Zosimos of Panopolis . In 327 BC, Alexander the Great was rewarded by the defeated King Porus , not with gold or silver but with 30 pounds of steel. A recent study has speculated that carbon nanotubes were included in its structure, which might explain some of its legendary qualities, though, given
6440-601: The Eresburg is known prior to the Saxon Wars (AD 770–785). During the Saxon Wars , the stronghold was repeatedly occupied by Widukind , leader of the recalcitrant Saxons (those refusing to adopt Christianity and the overlordship of the Franks ), and then abandoned to Charlemagne 's forces as the Saxons retreated to the home of Widukind's in-laws, today Denmark . Local lore states that as Charlemagne's forces approached,
6555-459: The Indian subcontinent began prior to the 3rd millennium BC. Archaeological sites in India, such as Malhar, Dadupur, Raja Nala Ka Tila, Lahuradewa, Kosambi and Jhusi , Allahabad in present-day Uttar Pradesh show iron implements in the period 1800–1200 BC. As the evidence from the sites Raja Nala ka tila, Malhar suggest the use of Iron in c. 1800/1700 BC. The extensive use of iron smelting
6670-770: The Indian subcontinent suggest Indianization of Southeast Asia beginning in the 4th to 2nd centuries BC during the late Iron Age. In Philippines and Vietnam , the Sa Huynh culture showed evidence of an extensive trade network. Sa Huynh beads were made from glass, carnelian, agate, olivine, zircon, gold and garnet; most of these materials were not local to the region and were most likely imported. Han-dynasty-style bronze mirrors were also found in Sa Huynh sites. Conversely, Sa Huynh produced ear ornaments have been found in archaeological sites in Central Thailand, as well as
6785-632: The Late Bronze Age continued into the Early Iron Age. Thus, there is a sociocultural continuity during this transitional period. In Iran, the earliest actual iron artifacts were unknown until the 9th century BC. For Iran, the best studied archaeological site during this time period is Teppe Hasanlu . In the Mesopotamian states of Sumer , Akkad and Assyria , the initial use of iron reaches far back, to perhaps 3000 BC. One of
6900-589: The Late Bronze Age. As part of the Late Bronze Age-Early Iron Age, the Bronze Age collapse saw the slow, comparatively continuous spread of iron-working technology in the region. It was long believed that the success of the Hittite Empire during the Late Bronze Age had been based on the advantages entailed by the "monopoly" on ironworking at the time. Accordingly, the invading Sea Peoples would have been responsible for spreading
7015-470: The Linz-Donawitz process of basic oxygen steelmaking (BOS), developed in 1952, and other oxygen steel making methods. Basic oxygen steelmaking is superior to previous steelmaking methods because the oxygen pumped into the furnace limited impurities, primarily nitrogen, that previously had entered from the air used, and because, with respect to the open hearth process, the same quantity of steel from
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#17327757932327130-488: The Romans, though ironworking remained the dominant technology until recent times. Elsewhere it may last until the early centuries AD, and either Christianization or a new conquest during the Migration Period . Iron working was introduced to Europe during the late 11th century BC, probably from the Caucasus , and slowly spread northwards and westwards over the succeeding 500 years. The Iron Age did not start when iron first appeared in Europe but it began to replace bronze in
7245-401: The alloying elements, primarily carbon, gives steel and cast iron their range of unique properties. In pure iron, the crystal structure has relatively little resistance to the iron atoms slipping past one another, and so pure iron is quite ductile , or soft and easily formed. In steel, small amounts of carbon, other elements, and inclusions within the iron act as hardening agents that prevent
7360-440: The archaeology of the Ancient Near East was developed during the 1920s and 1930s. Meteoric iron, a natural iron–nickel alloy , was used by various ancient peoples thousands of years before the Iron Age. The earliest-known meteoric iron artifacts are nine small beads dated to 3200 BC , which were found in burials at Gerzeh in Lower Egypt , having been shaped by careful hammering. The characteristic of an Iron Age culture
7475-427: The archaeology of the Ancient Near East. Its name harks back to the mythological " Ages of Man " of Hesiod . As an archaeological era, it was first introduced to Scandinavia by Christian Jürgensen Thomsen during the 1830s. By the 1860s, it was embraced as a useful division of the "earliest history of mankind" in general and began to be applied in Assyriology . The development of the now-conventional periodization in
7590-436: The austenite grain boundaries until the percentage of carbon in the grains has decreased to the eutectoid composition (0.8% carbon), at which point the pearlite structure forms. For steels that have less than 0.8% carbon (hypoeutectoid), ferrite will first form within the grains until the remaining composition rises to 0.8% of carbon, at which point the pearlite structure will form. No large inclusions of cementite will form at
7705-471: The austenite is for it to precipitate out of solution as cementite , leaving behind a surrounding phase of BCC iron called ferrite with a small percentage of carbon in solution. The two, cementite and ferrite, precipitate simultaneously producing a layered structure called pearlite , named for its resemblance to mother of pearl . In a hypereutectoid composition (greater than 0.8% carbon), the carbon will first precipitate out as large inclusions of cementite at
7820-430: The beginning of the Western Han dynasty . Yoon proposes that iron was first introduced to chiefdoms located along North Korean river valleys that flow into the Yellow Sea such as the Cheongcheon and Taedong Rivers. Iron production quickly followed during the 2nd century BC, and iron implements came to be used by farmers by the 1st century in southern Korea. The earliest known cast-iron axes in southern Korea are found in
7935-494: The boundaries in hypoeutectoid steel. The above assumes that the cooling process is very slow, allowing enough time for the carbon to migrate. As the rate of cooling is increased the carbon will have less time to migrate to form carbide at the grain boundaries but will have increasingly large amounts of pearlite of a finer and finer structure within the grains; hence the carbide is more widely dispersed and acts to prevent slip of defects within those grains, resulting in hardening of
8050-482: The capabilities of Neolithic kilns , which date back to 6000 BC and were able to produce temperatures greater than 900 °C (1,650 °F). In addition to specially designed furnaces, ancient iron production required the development of complex procedures for the removal of impurities, the regulation of the admixture of carbon, and the invention of hot-working to achieve a useful balance of hardness and strength in steel. The use of steel has also been regulated by
8165-479: The centers of origin were located in West Africa , Central Africa , and East Africa ; consequently, as these origin centers are located within inner Africa, these archaeometallurgical developments are thus native African technologies. Iron metallurgical development occurred 2631–2458 BC at Lejja, in Nigeria, 2136–1921 BC at Obui, in Central Africa Republic, 1895–1370 BC at Tchire Ouma 147, in Niger, and 1297–1051 BC at Dekpassanware, in Togo. Steel Steel
8280-455: The combination, bronze, which has a melting point lower than 1,083 °C (1,981 °F). In comparison, cast iron melts at about 1,375 °C (2,507 °F). Small quantities of iron were smelted in ancient times, in the solid-state, by heating the ore in a charcoal fire and then welding the clumps together with a hammer and in the process squeezing out the impurities. With care, the carbon content could be controlled by moving it around in
8395-417: The development of iron metallurgy, which was known by the 9th century BC. The large seal script is identified with a group of characters from a book entitled Shǐ Zhòu Piān ( c. 800 BC). Therefore, in China prehistory had given way to history periodized by ruling dynasties by the start of iron use, so "Iron Age" is not used typically to describe a period of Chinese history. Iron metallurgy reached
8510-531: The earliest smelted iron artifacts known is a dagger with an iron blade found in a Hattic tomb in Anatolia , dating from 2500 BC. The widespread use of iron weapons which replaced bronze weapons rapidly disseminated throughout the Near East (North Africa, southwest Asia ) by the beginning of the 1st millennium BC. The development of iron smelting was once attributed to the Hittites of Anatolia during
8625-497: The economics of the metallurgical advancements. The earliest tentative evidence for iron-making is a small number of iron fragments with the appropriate amounts of carbon admixture found in the Proto-Hittite layers at Kaman-Kalehöyük in modern-day Turkey, dated to 2200–2000 BC. Akanuma (2008) concludes that "The combination of carbon dating, archaeological context, and archaeometallurgical examination indicates that it
8740-452: The economies of melting and casting, can be heat treated after casting to make malleable iron or ductile iron objects. Steel is distinguishable from wrought iron (now largely obsolete), which may contain a small amount of carbon but large amounts of slag . Iron is commonly found in the Earth's crust in the form of an ore , usually an iron oxide, such as magnetite or hematite . Iron
8855-560: The emergence of the Iron Age proper by several centuries. Iron was being used in Mundigak to manufacture some items in the 3rd millennium BC such as a small copper/bronze bell with an iron clapper, a copper/bronze rod with two iron decorative buttons, and a copper/bronze mirror handle with a decorative iron button. Artefacts including small knives and blades have been discovered in the Indian state of Telangana which have been dated between 2400 BC and 1800 BC. The history of metallurgy in
8970-583: The end of the Bronze Age . The Iron Age in Europe is often considered as a part of the Bronze Age collapse in the ancient Near East . Anthony Snodgrass suggests that a shortage of tin and trade disruptions in the Mediterranean about 1300 BC forced metalworkers to seek an alternative to bronze. Many bronze implements were recycled into weapons during that time, and more widespread use of iron resulted in improved steel-making technology and lower costs. When tin became readily available again, iron
9085-498: The excavation of Ugarit. A dagger with an iron blade found in Tutankhamun's tomb , 13th century BC, was examined recently and found to be of meteoric origin. In Europe, the Iron Age is the last stage of prehistoric Europe and the first of the protohistoric periods, which initially means descriptions of a particular area by Greek and Roman writers. For much of Europe, the period came to an abrupt local end after conquest by
9200-648: The finest steel in the world exported to the Roman, Egyptian, Chinese and Arab worlds at that time – what they called Seric Iron . A 200 BC Tamil trade guild in Tissamaharama , in the South East of Sri Lanka, brought with them some of the oldest iron and steel artifacts and production processes to the island from the classical period . The Chinese and locals in Anuradhapura , Sri Lanka had also adopted
9315-521: The fire. Unlike copper and tin, liquid or solid iron dissolves carbon quite readily. All of these temperatures could be reached with ancient methods used since the Bronze Age . Since the oxidation rate of iron increases rapidly beyond 800 °C (1,470 °F), it is important that smelting take place in a low-oxygen environment. Smelting, using carbon to reduce iron oxides, results in an alloy ( pig iron ) that retains too much carbon to be called steel. The excess carbon and other impurities are removed in
9430-465: The first millennium BC. In Southern India (present-day Mysore ) iron appeared as early as 12th to 11th centuries BC; these developments were too early for any significant close contact with the northwest of the country. The Indian Upanishads mention metallurgy. and the Indian Mauryan period saw advances in metallurgy. As early as 300 BC, certainly by 200 AD, high-quality steel
9545-513: The form of charcoal) in a crucible, was produced in Merv by the 9th to 10th century AD. In the 11th century, there is evidence of the production of steel in Song China using two techniques: a "berganesque" method that produced inferior, inhomogeneous steel, and a precursor to the modern Bessemer process that used partial decarburization via repeated forging under a cold blast . Since
9660-480: The forms and character of the ornamentation of the northern European weapons resemble in some respects Roman arms, while in other respects they are peculiar and evidently representative of northern art. Citânia de Briteiros , located in Guimarães , Portugal, is one of the examples of archaeological sites of the Iron Age. This settlement (fortified villages) covered an area of 3.8 hectares (9.4 acres), and served as
9775-599: 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. Recent corporate average fuel economy (CAFE) regulations have given rise to a new variety of steel known as Advanced High Strength Steel (AHSS). This material is both strong and ductile so that vehicle structures can maintain their current safety levels while using less material. There are several commercially available grades of AHSS, such as dual-phase steel , which
9890-420: The ironworking Painted Grey Ware culture , dating from the 15th century BC , through to the reign of Ashoka in the 3rd century BC . The term "Iron Age" in the archaeology of South, East, and Southeast Asia is more recent and less common than for Western Eurasia. Africa did not have a universal "Bronze Age", and many areas transitioned directly from stone to iron. Some archaeologists believe that iron metallurgy
10005-498: The knowledge through that region. The idea of such a "Hittite monopoly" has been examined more thoroughly and no longer represents a scholarly consensus. While there are some iron objects from Bronze Age Anatolia, the number is comparable to iron objects found in Egypt and other places of the same time period; and only a small number of these objects are weapons. Dates are approximate; consult particular article for details. Iron metal
10120-567: The lack of nickel in the product) appeared in the Middle East , Southeast Asia and South Asia . African sites are revealing dates as early as 2000–1200 BC. However, some recent studies date the inception of iron metallurgy in Africa between 3000 and 2500 BC, with evidence existing for early iron metallurgy in parts of Nigeria, Cameroon, and Central Africa, from as early as around 2,000 BC. The Nok culture of Nigeria may have practiced iron smelting from as early as 1000 BC, while
10235-528: The late 2nd millennium BC ( c. 1300 BC). The earliest bloomery smelting of iron is found at Tell Hammeh , Jordan about 930 BC (determined from C dating ). The Early Iron Age in the Caucasus area is divided conventionally into two periods, Early Iron I, dated to about 1100 BC, and the Early Iron II phase from the tenth to ninth centuries BC. Many of the material culture traditions of
10350-550: The late Yayoi period ( c. 300 BC – 300 AD) or the succeeding Kofun period ( c. 250–538 AD), most likely from the Korean Peninsula and China. Distinguishing characteristics of the Yayoi period include the appearance of new pottery styles and the start of intensive rice agriculture in paddy fields. Yayoi culture flourished in a geographic area from southern Kyūshū to northern Honshū . The Kofun and
10465-439: The main production route. At the end of 2008, the steel industry faced a sharp downturn that led to many cut-backs. In 2021, it was estimated that around 7% of the global greenhouse gas emissions resulted from the steel industry. Reduction of these emissions are expected to come from a shift in the main production route using cokes, more recycling of steel and the application of carbon capture and storage technology. Steel
10580-450: The most part, however, p-block elements such as sulphur, nitrogen , phosphorus , and lead are considered contaminants that make steel more brittle and are therefore removed from steel during the melting processing. The density of steel varies based on the alloying constituents but usually ranges between 7,750 and 8,050 kg/m (484 and 503 lb/cu ft), or 7.75 and 8.05 g/cm (4.48 and 4.65 oz/cu in). Even in
10695-446: The movement of dislocations . The carbon in typical steel alloys may contribute up to 2.14% of its weight. Varying the amount of carbon and many other alloying elements, as well as controlling their chemical and physical makeup in the final steel (either as solute elements, or as precipitated phases), impedes the movement of the dislocations that make pure iron ductile, and thus controls and enhances its qualities. These qualities include
10810-531: The nearby Djenné-Djenno culture of the Niger Valley in Mali shows evidence of iron production from c. 250 BC. Iron technology across much of sub-Saharan Africa has an African origin dating to before 2000 BC. These findings confirm the independent invention of iron smelting in sub-Saharan Africa. Modern archaeological evidence identifies the start of large-scale global iron production about 1200 BC, marking
10925-580: The preparation of tools and weapons. It did not happen at the same time throughout Europe; local cultural developments played a role in the transition to the Iron Age. For example, the Iron Age of Prehistoric Ireland begins about 500 BC (when the Greek Iron Age had already ended) and finishes about 400 AD. The widespread use of the technology of iron was implemented in Europe simultaneously with Asia. The prehistoric Iron Age in Central Europe
11040-449: The product but only locally relieves strains and stresses locked up within the material. Annealing goes through three phases: recovery , recrystallization , and grain growth . The temperature required to anneal a particular steel depends on the type of annealing to be achieved and the alloying constituents. Quenching involves heating the steel to create the austenite phase then quenching it in water or oil . This rapid cooling results in
11155-707: The production methods of creating wootz steel from the Chera Dynasty Tamils of South India by the 5th century AD. In Sri Lanka, this early steel-making method employed a unique wind furnace, driven by the monsoon winds, capable of producing high-carbon steel. Since the technology was acquired from the Tamilians from South India, the origin of steel technology in India can be conservatively estimated at 400–500 BC. The manufacture of wootz steel and Damascus steel , famous for its durability and ability to hold an edge, may have been taken by
11270-426: The quality of the final product. Today more than 1.6 billion tons of steel is produced annually. Modern steel is generally identified by various grades defined by assorted standards organizations . The modern steel industry is one of the largest manufacturing industries in the world, but also one of the most energy and greenhouse gas emission intense industries, contributing 8% of global emissions. However, steel
11385-401: The steel. At the very high cooling rates produced by quenching, the carbon has no time to migrate but is locked within the face-centred austenite and forms martensite . Martensite is a highly strained and stressed, supersaturated form of carbon and iron and is exceedingly hard but brittle. Depending on the carbon content, the martensitic phase takes different forms. Below 0.2% carbon, it takes on
11500-561: The steel. The early modern crucible steel industry resulted from the invention of Benjamin Huntsman in the 1740s. Blister steel (made as above) was melted in a crucible or in a furnace, and cast (usually) into ingots. The modern era in steelmaking began with the introduction of Henry Bessemer 's process in 1855, the raw material for which was pig iron. His method let him produce steel in large quantities cheaply, thus mild steel came to be used for most purposes for which wrought iron
11615-637: The subsequent Asuka periods are sometimes referred to collectively as the Yamato period ; The word kofun is Japanese for the type of burial mounds dating from that era. Iron objects were introduced to the Korean peninsula through trade with chiefdoms and state-level societies in the Yellow Sea area during the 4th century BC, just at the end of the Warring States Period but prior to
11730-561: The technology of that time, such qualities were produced by chance rather than by design. Natural wind was used where the soil containing iron was heated by the use of wood. The ancient Sinhalese managed to extract a ton of steel for every 2 tons of soil, a remarkable feat at the time. One such furnace was found in Samanalawewa and archaeologists were able to produce steel as the ancients did. Crucible steel , formed by slowly heating and cooling pure iron and carbon (typically in
11845-600: The term is used infrequently for the archaeology of China. For the Ancient Near East, the establishment of the Achaemenid Empire c. 550 BC is used traditionally and still usually as an end date; later dates are considered historical according to the record by Herodotus despite considerable written records now being known from well back into the Bronze Age. In Central and Western Europe,
11960-521: The town's common folk would move into the Drachenholler , a vast system of underground gypsum caves beneath Eresburg, where they remained unnoticed until Charlemagne's people left. Though only a legend, the caves can still be seen, along with several watchtowers dated to the same time period (circa AD 800). Very near Eresburg is Priesterberg , a hill overlooking the valley of the Diemel. This
12075-525: The upper carbon content of steel, beyond which is cast iron. When carbon moves out of solution with iron, it forms a very hard, but brittle material called cementite (Fe 3 C). When steels with exactly 0.8% carbon (known as a eutectoid steel), are cooled, the austenitic phase (FCC) of the mixture attempts to revert to the ferrite phase (BCC). The carbon no longer fits within the FCC austenite structure, resulting in an excess of carbon. One way for carbon to leave
12190-481: The world by archaeological convention when the production of smelted iron (especially steel tools and weapons) replaces their bronze equivalents in common use. In Anatolia and the Caucasus , or Southeast Europe , the Iron Age began during the late 2nd millennium BC ( c. 1300 BC). In the Ancient Near East , this transition occurred simultaneously with the Late Bronze Age collapse , during
12305-488: Was attributed to Seth, the spirit of evil who according to Egyptian tradition governed the central deserts of Africa. In the Black Pyramid of Abusir , dating before 2000 BC, Gaston Maspero found some pieces of iron. In the funeral text of Pepi I , the metal is mentioned. A sword bearing the name of pharaoh Merneptah as well as a battle axe with an iron blade and gold-decorated bronze shaft were both found in
12420-400: Was cheaper, stronger and lighter, and forged iron implements superseded cast bronze tools permanently. In Central and Western Europe, the Iron Age lasted from c. 800 BC to c. 1 BC , beginning in pre-Roman Iron Age Northern Europe in c. 600 BC , and reaching Northern Scandinavian Europe about c. 500 BC . The Iron Age in the Ancient Near East
12535-718: Was developed in Southern India and Sri Lanka in the 1st millennium BCE. Metal production sites in Sri Lanka employed wind furnaces driven by the monsoon winds, capable of producing high-carbon steel. Large-scale wootz steel production in India using crucibles occurred by the sixth century BC, the pioneering precursor to modern steel production and metallurgy. High-carbon steel was produced in Britain at Broxmouth Hillfort from 490–375 BC, and ultrahigh-carbon steel
12650-457: Was developed in sub-Saharan Africa independently from Eurasia and neighbouring parts of Northeast Africa as early as 2000 BC . The concept of the Iron Age ending with the beginning of the written historiographical record has not generalized well, as written language and steel use have developed at different times in different areas across the archaeological record. For instance, in China, written history started before iron smelting began, so
12765-509: Was formerly used. The Gilchrist-Thomas process (or basic Bessemer process ) was an improvement to the Bessemer process, made by lining the converter with a basic material to remove phosphorus. Another 19th-century steelmaking process was the Siemens-Martin process , which complemented the Bessemer process. It consisted of co-melting bar iron (or steel scrap) with pig iron. These methods of steel production were rendered obsolete by
12880-438: Was produced globally, with 630,000,000 tonnes (620,000,000 long tons; 690,000,000 short tons) recycled. Modern steels are made with varying combinations of alloy metals to fulfil 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
12995-561: Was produced in southern India, by what would later be called the crucible technique . In this system, high-purity wrought iron, charcoal, and glass were mixed in a crucible and heated until the iron melted and absorbed the carbon. The protohistoric Early Iron Age in Sri Lanka lasted from 1000 BC to 600 BC. Radiocarbon evidence has been collected from Anuradhapura and Aligala shelter in Sigiriya . The Anuradhapura settlement
13110-706: Was produced in the Netherlands from the 2nd-4th centuries AD. The Roman author Horace identifies steel weapons such as the falcata in the Iberian Peninsula , while Noric steel was used by the Roman military . The Chinese of the Warring States period (403–221 BC) had quench-hardened steel, while Chinese of the Han dynasty (202 BC—AD 220) created steel by melting together wrought iron with cast iron, thus producing
13225-517: Was reportedly the location of Pagan sacrificial rites in the pre-Christian era. It is also thought to be the home of Irminsul , a sacred tree or pillar which represented the Germanic central pillar of the world. In AD 772, Charlemagne destroyed the Irminsul on Priesterberg (elsewhere reported as "near Paderborn " or "near Eresburg"). The Irminsul was replaced by a stone structure, possibly
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