Everything about the steel around us

• The history of making...
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The history of making steel Iron was in limited use long before it became During the Han Dynasty (202 BC–AD possible to smelt it. The first signs of iron 220), Chinese ironworking achieved a scale use come from Ancient Egypt and Sumer, where and sophistication not reached in the West around 4000 BC small items, such as the tips until the eighteenth century. In the first of spears and ornaments, were being fashioned century, the Han government established from iron recovered from meteorites About 6% ironworking as a state monopoly and built a of meteorites are composed of an iron-nickel series of large blast furnaces in Henan alloy, and iron recovered from meteorite province, each capable of producing several falls allowed ancient peoples to manufacture tons of iron per day. By this time, Chinese small  numbers  of  iron  artifacts. metallurgists had discovered how to puddle molten pig iron, stirring it in the open air Meteoric iron was also fashioned into tools until it lost its carbon and became wrought in precontact North America. Beginning around iron. (In Chinese, the process was called the year 1000, the Thule people of Greenland chao,  literally,  stir  frying.) began making harpoons and other edged tools from pieces of the Cape York meteorite. These Also during this time, Chinese metallurgists artifacts were also used as trade goods with had found that wrought iron and cast iron other Arctic peoples: tools made from the could be melted together to yield an alloy of Cape York meteorite have been found in intermediate carbon content, that is, steel. archaeological sites more than 1000 miles According to legend, the sword of Liu Bang, (1600 km) away. When the American polar the first Han emperor, was made in this explorer Robert Peary shipped the largest fashion. Some texts of the era mention piece of the meteorite to the American Museum "harmonizing the hard and the soft" in the of Natural History in New York City in 1897, context of ironworking; the phrase may refer it  still  weighed  over  33  tons. to  this  process. The name for iron in several ancient Steelmaking  in  India  and  Sri  Lanka languages means "sky metal" or something similar. In distant antiquity, iron was Perhaps as early as 300 BC, although regarded as a precious metal, suitable for certainly by AD 200, high quality steel was royal  ornaments. being produced in southern India also by what Europeans would later call the crucible Iron axehead from Swedish Iron Age, found at technique. In this system, high-purity Gotland,  Sweden wrought iron, charcoal, and glass were mixed in crucibles and heated until the iron melted The  Iron  Age and absorbed the carbon. One of the earliest evidence of steel making comes to us from Beginning between 3000 BC to 2000 BC Samanalawewa area in Sri Lanka where increasing numbers of smelted iron objects thousands of sites were found. (Ref. Juleff, (distinguishable from meteoric iron by their 1996). lack of nickel) appear in Anatolia, Egypt and Mesopotamia (see Iron: History). The oldest Export known samples of iron that appear to have been smelted from iron oxides are small lumps The resulting high-carbon steel, called in found at copper-smelting sites on the Sinai Persian and wootz by later Europeans, was Peninsula, dated to about 3000 BC. Some iron exported throughout much of Asia. The famous oxides are effective fluxes for copper Damascus swords were possibly made of steel smelting; it is possible that small amounts imported  from  India. of metallic iron were made as a by-product of copper and bronze production throughout the A solid pillar of curiously rust-resistant Bronze  Age. iron—often mistakenly characterized as being made of steel— forged or cast in In Anatolia, smelted iron was occasionally the 4th century AD, and which has stood for used for ornamental weapons: an iron-bladed many centuries next to the Qutab Minar in the dagger with a bronze hilt has been recovered Qutb complex in Delhi, is a testimony of the from a Hattic tomb dating from 2500 BC. Also, metallurgical skills of Indian artisans. The the Egyptian ruler Tutankhamun died in 1323 metal is variously described as cast iron or BC and was buried with an iron dagger with a wrought iron. Its resistance to oxidation is golden hilt. An Ancient Egyptian sword theorized to be due to the formation of a bearing the name of pharaoh Merneptah as well protective patina catalyzed by the a residue as a battle axe with an iron blade and of  phosphorus  in  the  ore. gold-decorated bronze haft were both found in the excavation of Ugarit (see Ugarit). The Steelmaking  in  the  Middle  East early Hittites are known to have bartered iron for silver, at a rate of 40 times the By the 9th century, smiths in the Abbasid iron's  weight,  with  Assyria. caliphate had developed techniques for forging wootz to produce steel blades of Iron did not, however, replace bronze as the unusual flexibility and sharpness (Damascus chief metal used for weapons and tools for steel). several centuries, despite some attempts. Working iron required more fuel and Recent research has established strong significantly more labor than working bronze, evidence supporting the theory that the and the quality of iron produced by early distinct surface patterns on Damascus steel smiths may have been inferior to bronze as a blades result from a carbide-banding material for tools. Then, between 1200 and phenomenon produced by the microsegregation 1000 BC, iron tools and weapons displaced of minor amounts of carbide-forming elements bronze ones throughout the near east. This present in the wootz ingots from which the process appears to have begun in the Hittite blades were forged. Further, it is likely Empire around 1300 BC, or in Cyprus and that wootz Damascus blades with damascene southern Greece, where iron artifacts patterns may have been produced only from dominate the archaeological record after 1050 wootz ingots supplied from those regions of BC. Mesopotamia was fully into the Iron Age India having appropriate impurity-containing by 900 BC, central Europe by 800 BC. The ore  deposits. reason for this sudden adoption of iron remains a topic of debate among Ironworking  in  medieval  Europe archaeologists. One prominent theory is that warfare and mass migrations beginning around The middle ages in Europe saw the 1200 BC disrupted the regional tin trade, construction of progressively larger forcing a switch from bronze to iron. Egypt, bloomeries. By the 8th century, smiths in on the other hand, did not experience such a northern Spain had developed a style that rapid transition from the bronze to iron become known as a Catalan forge, a furnace ages: although Egyptian smiths did produce about 1 meter (3 feet) tall, capable of iron artifacts, bronze remained in widespread smelting up to 150 kg (350 lb) of iron in use there until after Egypt's conquest by each batch. In succeeding centuries, smiths Assyria  in  663  BC. in the Frankish empire and later the Holy Roman Empire scaled up this basic design, Iron smelting at this time was based on the increasing the height of the flue to as tall bloomery, a furnace where bellows were used as 5 meters (16 feet) and smelting as much as to force air through a pile of iron ore and 350 kg (750 lb) of iron in each batch. These burning charcoal. The carbon monoxide larger furnaces required more draft than produced by the charcoal reduced the iron could be provided by human power, and forging oxides to metallic iron, but the bloomery was the large blooms that resulted was also not hot enough to melt the iron. Instead, the beyond the capabilities of a single man. To iron collected in the bottom of the furnace this end, waterwheels were employed to power as a spongy mass, or bloom, whose pores were the  bellows  and  hammers. filled with ash and slag. The bloom then had to be reheated to soften the iron and melt Eventually, the scaling up of the bloomery the slag, and then repeatedly beaten and reached a point where the furnace was hot folded to force the molten slag out of it. enough to produce cast iron. Although the The result of this time-consuming and brittle cast iron may initially have been a laborious process was wrought iron, a nuisance to the smith, as it was too brittle malleable but fairly soft alloy containing to be forged, the spread of cannons to Europe little  carbon. in the 1300s provided an application for iron casting:  cast  iron  cannonballs. Wrought iron can be carburized into a mild steel by holding it in a charcoal fire for The oldest known blast furnace in Europe was prolonged periods of time. By the beginning constructed at Lapphyttan in Sweden, sometime of the Iron Age, smiths had discovered that between 1150 and 1350. Other early European iron that was repeatedly reforged produced a blast furnaces were built throughout the higher quality of metal. Quench-hardening was Rhine valley: blast furnaces were in also known by this time. The oldest operation near Liege (a city in modern-day quench-hardened steel artifact is a knife Belgium) in the 1340s, and at Massevaux in found  on  Cyprus at a site dated to 1100 BC. France  by  1409. Developments  in  China The first English blast furnace was not built until 1491, when Queenstock furnace was built Archaeologists and historians debate whether at Buxted, followed by one commissioned Henry bloomery-based ironworking ever spread to VII at Newbridge, in 1496 in a part of Sussex China from the Middle East. Around 500 BC, known as the Weald. Despite this late start, however, metalworkers in the southern state the production of English iron foundries of Wu developed an iron smelting technology rapidly grew, in no small part due to foreign that would not be practiced in Europe until craftsmen hired by Henry to bring the craft late medieval times. In Wu, iron smelters of iron casting to England. In 1543, William achieved a temperature of 1130°C, hot Levett, an English rector who doubled as a enough to be considered a blast furnace. At Wealden ironmaster , and Peter Baude, a this temperature, iron combines with 4.3% French craftsman in Henry VIII's employ, cast carbon and melts. As a liquid, iron can be the Weald's first one-piece iron cannon. cast into molds, a method far less laborious English iron cannons gained a reputation for than individually forging each piece of iron being superior to, and less expensive than, from  a  bloom. the bronze cannons made elsewhere in Europe, and at least initially, efforts to copy them Cast iron is rather brittle and unsuitable outside the Weald failed. The superiority of for striking implements. It can, however, be English cannons over Spanish ones has been decarburized to steel or wrought iron by credited as one factor in England's 1588 heating it in air for several days. In China, defeat  of  the  Spanish  Armada. these ironworking methods spread northward, and by 300 BC, iron was the material of In 1619, Jan Andries Moerbeck, a Dutch choice throughout China for most tools and ironmaster, began importing Wealden iron ore weapons. A mass grave in Hebei province, for comparison to the ore available on the dated to the early third century BC, contains Continent. One difference he observed was several soldiers buried with their weapons that the English ore contained some and other equipment. The artifacts recovered calcareous material, and soon after, Dutch from this grave are variously made of wrought ironmasters introduced the use of limestone iron, cast iron, malleabilized cast iron, and as a flux in the blast furnace. This practice quench-hardened steel, with only a few, improved the separation of slag from the cast probably  ornamental,  bronze  weapons. iron and improved the quality of Continental cast iron. 1 A B C D E F 97 99 100 101 102 103 105 106 107 108 109 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138