|Other iron-based materials|
Crucible steel is steel made by melting pig iron (cast iron), iron, and sometimes steel, often along with sand, glass, ashes, and other fluxes, in a crucible. In ancient times steel and iron were impossible to melt using charcoal or coal fires, which could not produce temperatures high enough. However, pig iron, having a higher carbon content and thus a lower melting point, could be melted, and by soaking wrought iron or steel in the liquid pig-iron for a long time, the carbon content of the pig iron could be reduced as it slowly diffused into the iron. Crucible steel of this type was produced in South and Central Asia during the medieval era. This generally produced a very hard steel, but also a composite steel that was inhomogeneous, consisting of a very high-carbon steel (formerly the pig-iron) and a lower-carbon steel (formerly the wrought iron). This often resulted in an intricate pattern when the steel was forged, filed or polished, with possibly the most well-known examples coming from the wootz steel used in Damascus swords. The steel was often much higher in carbon content and in quality (lacking impurities) in comparison with other methods of steel production of the time because of the use of fluxes.
In Europe, crucible steel was developed by Benjamin Huntsman in England in the 18th century. Huntsman used coke rather than coal or charcoal, achieving temperatures high enough to melt steel and dissolve iron. Huntsman's process differed from some of the wootz processes in that it used a longer time to melt the steel and to cool it down and thus allowed more time for the diffusion of carbon.Huntsman's process used iron and steel as raw materials, in the form of blister steel, rather than direct conversion from cast iron as in puddling or the later Bessemer process. The ability to fully melt the steel removed any inhomogeneities in the steel, allowing the carbon to dissolve evenly into the liquid steel and negating the prior need for extensive blacksmithing in an attempt to achieve the same result. Similarly, it allowed steel to be cast by pouring into molds. The use of fluxes allowed nearly complete extraction of impurities from the liquid, which could then simply float to the top for removal. This produced the first steel of modern quality, providing a means of efficiently changing excess wrought iron into useful steel. Huntsman's process greatly increased the European output of quality steel suitable for use in items like knives, tools, and machinery, helping to pave the way for the Industrial revolution.
Iron alloys are most broadly divided by their carbon content: cast iron has 2–4% carbon impurities; wrought iron oxidizes away most of its carbon, to less than 0.1%. The much more valuable steel has a delicately intermediate carbon fraction, and its material properties range according to the carbon percentage: high carbon steel is stronger but more brittle than low carbon steel. Crucible steel sequesters the raw input materials from the heat source, allowing precise control of carburization (raising) or oxidation (lowering carbon content). Fluxes, such as limestone, could be added to the crucible to remove or promote sulfur, silicon, and other impurities, further altering its material qualities.
Various methods were used to produce crucible steel. According to Islamic texts such as al-Tarsusi and Abu Rayhan Biruni, three methods are described for indirect production of steel.The medieval Islamic historian Abu Rayhan Biruni (c. 973–1050) provides the earliest reference of the production of Damascus steel. The first, and the most common, traditional method is solid state carburization of wrought iron. This is a diffusion process in which wrought iron is packed in crucibles or a hearth with charcoal, then heated to promote diffusion of carbon into the iron to produce steel. Carburization is the basis for the wootz process of steel. The second method is the decarburization of cast iron by removing carbon from the cast iron. The third method uses wrought iron and cast iron. In this process, wrought iron and cast iron may be heated together in a crucible to produce steel by fusion. In regard to this method Abu Rayhan Biruni states: "this was the method used in Hearth". It is proposed that the Indian method refers to Wootz carburization method; i.e., the Mysore or Tamil processes.
Variations of co-fusion process have been found primarily in Persia and Central Asia but have also been found in Hyderabad, Indiacalled Deccani or Hyderabad process. For the carbon, a variety of organic materials are specified by the contemporary Islamic authorities, including pomegranate rinds, acorns, fruit skins like orange peel, leaves as well as the white of egg and shells. Slivers of wood are mentioned in some of the Indian sources, but significantly none of the sources mention charcoal.
Crucible steel is generally attributed to production centres in India and Sri Lanka where it was produced using the so-called "wootz" process, and it is assumed that its appearance in other locations was due to long distance trade.Only recently it has become apparent that places in Central Asia like Merv in Turkmenistan and Akhsiket in Uzbekistan were important centres of production of crucible steel. The Central Asian finds are all from excavations and date from the 8th to 12th centuries CE, while the Indian/Sri Lankan material is as early as 300 BCE. India's iron ore had trace vanadium and other alloying elements leading to increased hardenability in Indian crucible steel which was famous throughout the middle east for its ability to retain an edge.
While crucible steel is more attributed to the Middle East in early times, pattern welded swords, incorporating high-carbon, and likely crucible steel, have been discovered in Europe, from the 3rd century CE, [ who? ] that the process of making these blades originated in the Middle East and subsequently had been traded during the Volga Trade Route days.particularly in Scandinavia. Swords bearing the brand name: Ulfberht, and dating to a 200-year period from the 9th century to the early 11th century, are prime examples of the technique. It is speculated by many
In the first centuries of the Islamic period, some scientific studies on swords and steel appeared. The best known of these are by Jabir ibn Hayyan 8th century, al-Kindi 9th century, Al-Biruni in the early 11th century, al-Tarsusi in the late 12th century, and Fakhr-i-Mudabbir 13th century.
There are many ethnographic accounts of Indian crucible steel production; however, scientific investigations of the remains of crucible steel production have only been published for four regions: three in India and one in Sri Lanka. [ what language is this? ] or hookoo[ what language is this? ]. European accounts from the 17th century onwards have referred to the repute and manufacture of "wootz", a traditional crucible steel made specially in parts of southern India in the former provinces of Golconda, Mysore and Salem. As yet the scale of excavations and surface surveys is too limited to link the literary accounts to archaeometallurgical evidence.Indian/Sri Lankan crucible steel is commonly referred to as wootz, which is generally agreed to be an English corruption of the word ukko
The proven sites of crucible steel production in south India, e.g. at Konasamudram and Gatihosahalli, date from at least the late medieval period, 16th century.One of the earliest known potential sites, which shows some promising preliminary evidence that may be linked to ferrous crucible processes in Kodumanal, near Coimbatore in Tamil Nadu. The site is dated between the third century BCE and the third century CE. By the seventeenth century the main centre of crucible steel production seems to have been in Hyderabad. The process was apparently quite different from that recorded elsewhere. Wootz from Hyderabad or the Decanni process for making watered blades involved a co-fusion of two different kinds of iron: one was low in carbon and the other was a high-carbon steel or cast iron. Wootz steel was widely exported and traded throughout ancient Europe, China, the Arab world, and became particularly famous in the Middle East, where it became known as Damascus steel.
Recent archaeological investigations have suggested that Sri Lanka also supported innovative technologies for iron and steel production in antiquity.The Sri Lankan system of crucible steel making was partially independent of the various Indian and Middle Eastern systems. Their method was something similar to the method of carburization of wrought iron. The earliest confirmed crucible steel site is located in the knuckles range in the northern area of the Central Highlands of Sri Lanka dated to 6th −10th centuries CE. In twelfth century the land of Serendib (Sri Lanka) seems to have been the main supplier of crucible steel, but over the centuries production slipped back, and by the nineteenth century just a small industry survived in the Balangoda district of the central southern highlands.
A series of excavations at Samanalawewa indicated the unexpected and previously unknown technology of west-facing smelting sites, which are different types of steel production.These furnaces were used for direct smelting to steel. These are named "west facing" because they were located on the western sides of hilltops to use the prevailing wind in the smelting process. Sri Lankan furnace steels were known and traded between the 9th and 11th centuries and earlier, but apparently not later. These sites were dated to the 7th–11th centuries. The coincidence of this dating with the 9th century Islamic reference to Sarandib is of great importance. The crucible process existed in India at the same time that the west- facing technology was operating in Sri Lanka.
Central Asia has a rich history of crucible steel production, beginning during the late 1st millennium CE.From the sites in modern Uzbekistan and Merv in Turkmenistan, there is good archaeological evidence for the large scale production of crucible steel. They all belong in broad terms to the same early medieval period between the late 8th or early 9th and the late 12th century CE, contemporary with the early crusades.
The two most prominent crucible steel sites in eastern Uzbekistan carrying the Ferghana Process are Akhsiket and Pap in the Ferghana Valley, whose position within the Great Silk Road has been historically and archaeologically proved.The material evidence consists of large number of archaeological finds relating to steel making from 9th–12th centuries CE in the form of hundreds of thousands of fragments of crucibles, often with massive slag cakes. Archaeological work at Akhsiket, has identified that the crucible steel process was of the carburization of iron metal. This process appears to be typical of and restricted to the Ferghana Valley in eastern Uzbekistan, and it is therefore called the Ferghana Process. This process lasted in that region for roughly four centuries..
Evidence of the production of crucible steel have been found in Merv, Turkmenistan, a major city on the 'Silk Road'. The Islamic scholar al-Kindi (801–866 CE) mentions that during the ninth century CE the region of Khorasan, the area to which the cities Nishapur, Merv, Herat and Balkh belong, was a steel manufacturing centre.Evidence from a metallurgical workshop at Merv, dated to the ninth- early tenth century CE, provides an illustration of the co-fusion method of steel production in crucibles, about 1000 years earlier than the distinctly different wootz process. The crucible steel process at Merv might be seen as technologically related to what Bronson (1986, 43) calls Hyderabad process, a variation of the wootz process, after the location of the process documented by Voysey in the 1820s.
The first European references to crucible steel seem to be no earlier than the Post Medieval period.European experiments with “Damascus” steels go back to at least the sixteenth century, but it was not until the 1790s that laboratory researchers began to work with steels that were specifically known to be Indian/wootz. At this time, Europeans knew of India's ability to make crucible steel from reports brought back by travellers who had observed the process at several places in southern India.
From the mid-17th century onwards, European travellers to the Indian subcontinent wrote numerous vivid eyewitness accounts of the production of steel there. These include accounts by Jean Baptist Tavernier in 1679, Francis Buchanan in 1807, and H.W. Voysey in 1832.The 18th, 19th and early 20th century saw a heady period of European interest in trying to understand the nature and properties of wootz steel. Indian wootz engaged the attention of some of the best-known scientists. One was Michael Faraday who was fascinated by wootz steel. It was probably the investigations of George Pearson, reported at the Royal Society in 1795, which had the most far-reaching impact in terms of kindling interest in wootz amongst European scientists. He was the first of these scientists to publish his results and, incidentally, the first to use the word "wootz" in print.
Another investigator, David Mushet, was able to infer that wootz was made by fusion.David Mushet patented his process in 1800. He made his report in 1805. As it happens, however, the first successful European process had been developed by Benjamin Huntsman some 50 years previously in the 1740s.
Benjamin Huntsman was a clockmaker in search of a better steel for clock springs. In Handsworth near Sheffield, he began producing steel in 1740 after years of experimenting in secret. Huntsman's system used a coke-fired furnace capable of reaching 1,600 °C, into which up to twelve clay crucibles, each capable of holding about 15 kg of iron, were placed. When the crucibles or "pots" were white-hot, they were charged with lumps of blister steel, an alloy of iron and carbon produced by the cementation process, and a flux to help remove impurities. The pots were removed after about 3 hours in the furnace, impurities in the form of slag skimmed off, and the molten steel poured into moulds to end up as cast ingots. Complete melting of the steel produced a highly uniform crystal structure upon cooling, which gave the metal increased tensile strength and hardness in comparison with other steels being made at the time.
Before the introduction of Huntsman's technique, Sheffield produced about 200 tonnes of steel per year from Swedish wrought iron (see Oregrounds iron). The introduction of Huntsman's technique changed this radically: one hundred years later the amount had risen to over 80,000 tonnes per year, or almost half of Europe's total production. Sheffield developed from a small township into one of Europe's leading industrial cities.
The steel was produced in specialised workshops called 'crucible furnaces', which consisted of a workshop at ground level and a subterranean cellar. The furnace buildings varied in size and architectural style, growing in size towards the latter part of the 19th century as technological developments enabled multiple pots to be "fired" at once, using gas as a heating fuel. Each workshop had a series of standard features, such as rows of melting holes, teaming pits,[ clarification needed ] roof vents, rows of shelving for the crucible pots and annealing furnaces to prepare each pot before firing. Ancillary rooms for weighing each charge and for the manufacture of the clay crucibles were either attached to the workshop, or located within the cellar complex. The steel, originally intended for making clock springs, was later used in other applications such as scissors, axes and swords.
Sheffield's Abbeydale Industrial Hamlet operates for the public a scythe-making works, which dates from Huntsman's times and is powered by a water wheel, using crucible steel made at the site.
Previous to Huntsman, the most common method of producing steel was the manufacture of shear steel. In this method, blister steel produced by cementation was used, which consisted of a core of wrought iron surrounded by a shell of very high-carbon steel, typically ranging from 1.5 to 2.0% carbon. To help homogenize the steel, it was pounded into flat plates, which were stacked and forge welded together. This produced steel with alternating layers of steel and iron. The resulting billet could then be hammered flat, cut into plates, which were stacked and welded again, thinning and compounding the layers, and evening out the carbon more as it slowly diffused out of the high-carbon steel into the lower-carbon iron. However, the more the steel was heated and worked, the more it tended to decarburize, and this outward diffusion occurs much faster than the inward diffusion between layers. Thus, further attempts to homogenize the steel resulted in a carbon content too low for use in items like springs, cutlery, swords, or tools. Therefore, steel intended for use in such items, especially tools, was still being made primarily by the slow and arduous bloomery process in very small amounts and at high cost, which, albeit better, had to be manually separated from the wrought iron and was still impossible to fully homogenize in the solid state.
Huntsman's process was the first to produce a fully homogeneous steel. Unlike previous methods of steel production, the Huntsman process was the first to fully melt the steel, allowing the full diffusion of carbon throughout the liquid. With the use of fluxes it also allowed the removal of most impurities, producing the first steel of modern quality. Due to carbon's high melting point (nearly triple that of steel) and its tendency to oxidize (burn) at high temperatures, it cannot usually be added directly to molten steel. However, by adding wrought iron or pig iron, allowing it to dissolve into the liquid, the carbon content could be carefully regulated (in a way similar to Asian crucible-steels but without the stark inhomogeneities indicative of those steels). Another benefit was that it allowed other elements to be alloyed with the steel. Huntsman was one of the first to begin experimenting with the addition of alloying agents like manganese to help remove impurities such as oxygen from the steel. His process was later used by many others, such as Robert Hadfield and Robert Forester Mushet, to produce the first alloy steels like mangalloy, high-speed steel, and stainless steel.
Due to variations in the carbon content of the blister steel, the carbon steel produced could vary in carbon content between crucibles by as much as 0.18%, but on average produced a eutectoid steel containing ~ 0.79% carbon. Due to the quality and high hardenability of the steel, it was quickly adopted for the manufacture of tool steel, machine tools, cutlery, and many other items. Because no oxygen was blown through the steel, it exceeded Bessemer steel in both quality and hardenability, so Huntsman's process was used for manufacturing tool steel until better methods, utilizing an electric arc, were developed in the early 20th century.
In another method, developed in the United States in the 1880s, iron and carbon were melted together directly to produce crucible steel.Throughout the 19th century and into the 1920s a large amount of crucible steel was directed into the production of cutting tools, where it was called tool steel.
The crucible process continued to be used for specialty steels, but is today obsolete. Similar quality steels are now made with an electric arc furnace. Some uses of tool steel were displaced, first by high-speed steeland later by materials such as tungsten carbide.
Another form of crucible steel was developed in 1837 by the Russian engineer Pavel Anosov. His technique relied less on the heating and cooling, and more on the quenching process of rapidly cooling the molten steel when the right crystal structure had formed within. He called his steel bulat; its secret died with him. In the United States crucible steel was pioneered by William Metcalf.
An alloy is an admixture of metals, or a metal combined with one or more other elements. For example, combining the metallic elements gold and copper produces red gold, gold and silver becomes white gold, and silver combined with copper produces sterling silver. Combining iron with non-metallic carbon or silicon produces alloys called steel or silicon steel. The resulting mixture forms a substance with properties that often differ from those of the pure metals, such as increased strength or hardness. Unlike other substances that may contain metallic bases but do not behave as metals, such as aluminium oxide (sapphire), beryllium aluminium silicate (emerald) or sodium chloride (salt), an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, opacity, and luster. Alloys are used in a wide variety of applications, from the steel alloys, used in everything from buildings to automobiles to surgical tools, to exotic titanium alloys used in the aerospace industry, to beryllium-copper alloys for non-sparking tools. In some cases, a combination of metals may reduce the overall cost of the material while preserving important properties. In other cases, the combination of metals imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength. Examples of alloys are steel, solder, brass, pewter, duralumin, bronze, and amalgams.
Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. It is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure.
Damascus steel was the forged steel of the blades of swords smithed in the Near East from ingots of Wootz steel either imported from Southern India or made in production centres in Sri Lanka, or Khorasan, Iran. These swords are characterized by distinctive patterns of banding and mottling reminiscent of flowing water, sometimes in a "ladder" or "rose" pattern. Such blades were reputed to be tough, resistant to shattering, and capable of being honed to a sharp, resilient edge.
Steel is an alloy made up of iron with typically a few tenths of a percent of carbon to improve its strength and fracture resistance compared to iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant need typically an additional 11% chromium. Because of its high tensile strength and low cost, steel is used in buildings, infrastructure, tools, ships, trains, cars, machines, electrical appliances, and weapons. Iron is the base metal of steel. Depending on the temperature, it can take two crystalline forms : body-centred cubic and face-centred cubic. The interaction of the allotropes of iron with the alloying elements, primarily carbon, gives steel and cast iron their range of unique properties.
The Bessemer process was the first inexpensive industrial process for the mass production of steel from molten pig iron before the development of the open hearth furnace. The key principle is removal of impurities from the iron by oxidation with air being blown through the molten iron. The oxidation also raises the temperature of the iron mass and keeps it molten.
Wrought iron is an iron alloy with a very low carbon content in contrast to that of cast iron. It is a semi-fused mass of iron with fibrous slag inclusions, which gives it a "grain" resembling wood that is visible when it is etched or bent to the point of failure. Wrought iron is tough, malleable, ductile, corrosion resistant, and easily welded.
A crucible is a ceramic or metal container in which metals or other substances may be melted or subjected to very high temperatures. While crucibles historically were usually made from clay, it can be made from any material that withstands temperatures high enough to melt or otherwise alter its contents.
Steelmaking is the process of producing steel from iron ore and/or scrap. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur and excess carbon are removed from the sourced iron, and alloying elements such as manganese, nickel, chromium, carbon and vanadium are added to produce different grades of steel. Limiting dissolved gases such as nitrogen and oxygen and entrained impurities in the steel is also important to ensure the quality of the products cast from the liquid steel.
Wootz steel is a crucible steel characterized by a pattern of bands and high carbon content. These bands are formed by sheets of microscopic carbides within a tempered martensite or pearlite matrix in higher carbon steel, or by ferrite and pearlite banding in lower carbon steels. It was a pioneering steel alloy invented in Southern India and Sri Lanka in the mid-1st millennium BC and exported globally.
The cementation process is an obsolete technology for making steel by carburization of iron. Unlike modern steelmaking, it increased the amount of carbon in the iron. It was apparently developed before the 17th century. Derwentcote Steel Furnace, built in 1720, is the earliest surviving example of a cementation furnace. Another example in the UK is the cementation furnace in Doncaster Street, Sheffield.
A bloomery is a type of furnace once used widely for smelting iron from its oxides. The bloomery was the earliest form of smelter capable of smelting iron. Bloomeries produce a porous mass of iron and slag called a bloom. The mix of slag and iron in the bloom, termed sponge iron, is usually consolidated and further forged into wrought iron. Blast furnaces, which produce pig iron, have largely superseded bloomeries.
Case-hardening or surface hardening is the process of hardening the surface of a metal object while allowing the metal deeper underneath to remain soft, thus forming a thin layer of harder metal at the surface. For iron or steel with low carbon content, which has poor to no hardenability of its own, the case-hardening process involves infusing additional carbon or nitrogen into the surface layer. Case-hardening is usually done after the part has been formed into its final shape, but can also be done to increase the hardening element content of bars to be used in a pattern welding or similar process. The term face hardening is also used to describe this technique, when discussing modern armour.
The history of metallurgy in the Indian subcontinent began prior to the 3rd millennium BCE and continued well into the British Raj. Metals and related concepts were mentioned in various early Vedic age texts. The Rigveda already uses the Sanskrit term Ayas(आयस) (metal). The Indian cultural and commercial contacts with the Near East and the Greco-Roman world enabled an exchange of metallurgic sciences. With the advent of the Mughals, foreign Mughal Empire further improved the established tradition of metallurgy and metal working in India.
Puddling is a step in the manufacture of high-grade iron in a crucible or furnace. It was invented in Great Britain during the Industrial Revolution. The molten pig iron was stirred in a reverberatory furnace, in an oxidizing environment, resulting in wrought iron. It was one of the most important processes of making the first appreciable volumes of valuable and useful bar iron without the use of charcoal. Eventually, the furnace would be used to make small quantities of specialty steels.
A Walloon forge is a type of finery forge that decarbonizes pig iron into wrought iron.
Ferrous metallurgy, the metallurgy of iron and its alloys, began in prehistory. The earliest surviving iron artifacts, from the 4th millennium BC in Egypt, were made from meteoritic iron-nickel. It is not known when or where the smelting of iron from ores began, but by the end of the 2nd millennium BC iron was being produced from iron ores from at least Greece to India, and in Sub-Saharan Africa. The use of wrought iron was known by the 1st millennium BC, and its spread defined the Iron Age. During the medieval period, smiths in Europe found a way of producing wrought iron from cast iron using finery forges. All these processes required charcoal as fuel.
Tamil culture is the culture of the Tamil people. Tamil culture is rooted in the arts and ways of life of Tamils in India, Sri Lanka, Malaysia, Singapore, and across the globe. Tamil culture is expressed in language, literature, music, dance, theatre, folk arts, martial arts, painting, sculpture, architecture, sports, media, comedy, cuisine, costumes, celebrations, philosophy, religions, traditions, rituals, organizations, science, and technology.
Gold parting is the separating of gold from silver. Gold and silver are often extracted from the same ores and are chemically similar and therefore hard to separate. Over the centuries special means of separation have been invented.
A laminated steel blade or piled steel is a knife, sword, or other tool blade made out of layers of differing types of steel, rather than a single homogeneous alloy. The earliest steel blades were laminated out of necessity, due to the early bloomery method of smelting iron, which made production of steel expensive and inconsistent. Laminated steel offered both a way to average out the properties of the steel, as well as a way to restrict high carbon steel to the areas that needed it most. Laminated steel blades are still produced today for specialized applications, where different requirements at different points in the blade are met by use of different alloys, forged together into a single blade.
The iron and steel industries are among the most important industries in India. India replaces Japan as second top steel producer in January,2019. As per worldsteel, India's crude steel production in 2018 was at 106.5 MT, 4.9% increase from 101.5 MT in 2017, means that India has replaced Japan as world second largest steel production country. Japan produced 104.3 MT in year 2018, decrease of 0.3% compared to year 2017. Industry produced 82.68 million tons of total finished steel and 9.7 million tons of raw iron. Most iron and steel in India is produced from the iron ore.
Metalworking History Detailed from 9000 BC