India, containing 98% wrought iron Wrought iron is an with a very low (less than 0.08%) content in contrast to (2.1% to 4%). It is a semi-fused mass of iron with fibrous (up to 2% by weight), 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. Before the development of effective methods of and the availability of large quantities of steel, wrought iron was the most common form of malleable iron. A wrought product is one that has been mechanically worked by forging, extruding, rolling, hammering, etc., to change its form and properties. Wrought iron is a particular worked-iron product that is seldom produced today, as other cheaper, superior products are used instead. Historically, a modest amount of wrought iron was refined into, which was used mainly to produce,,, and other edged tools as well as springs and files.

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The demand for wrought iron reached its peak in the 1860s, being in high demand for and use. However, as properties such as brittleness of improved with better and as thanks to the and the, the use of wrought iron declined. Many items, before they came to be made of, were produced from wrought iron, including,,,,,, and steam pipes,,,,, wagon tires, straps for timber, and, among many other things. Wrought iron is no longer produced on a commercial scale. Many products described as wrought iron, such as, and, are actually made of mild steel.

They retain that description because they are made to resemble objects which in the past were wrought (worked) by hand by a (although many decorative iron objects, including fences and gates, were often cast rather than wrought). The puddling process of smelting iron ore to make wrought iron from pig iron, the right half of the illustration (not shown) displays men working a, Tiangong Kaiwu published in 1637, written by (1587–1666). During the Han dynasty, new iron smelting processes led to the manufacture of new wrought iron implements for use in agriculture, such as the and.

In addition to accidental lumps of low-carbon wrought iron produced by excessive injected air in ancient Chinese. The ancient Chinese created wrought iron by using the at least by the 2nd century BC, the earliest specimens of and fined into wrought iron and found at the early Han Dynasty (202 BC – 220 AD) site at Tieshengguo. Pigott speculates that the finery forge existed in the previous (403–221 BC), due to the fact that there are wrought iron items from China dating to that period and there is no documented evidence of the ever being used in China. The fining process involved liquifying cast iron in a fining hearth and from the molten cast iron through. Wagner writes that in addition to the Han Dynasty hearths believed to be fining hearths, there is also pictoral evidence of the fining hearth from a tomb mural dated 1st to 2nd century AD, as well as a hint of written evidence in the 4th century AD Daoist text.

Wrought iron has been used for many centuries, and is the 'iron' that is referred to throughout Western history. The other form of iron,, was in use in China since ancient times but was not introduced into Western Europe until the 15th century; even then, due to its brittleness, it could be used for only a limited number of purposes. Throughout much of the Middle Ages iron was produced by the direct reduction of ore in manually operated, although had begun to be employed by 1104. The raw material produced by all indirect processes is pig iron.

It has a high carbon content and as a consequence it is brittle and could not be used to make hardware. The was the first of the indirect processes, developed by 1203, but bloomery production continued in many places. The process depended on the development of the blast furnace, of which medieval examples have been discovered at, Sweden and in. The bloomery and osmond processes were gradually replaced from the 15th century by processes, of which there were two versions, the German and Walloon.

They were in turn replaced from the late 18th century by, with certain variants such as the Swedish. Those, too, are now obsolete, and wrought iron is no longer manufactured commercially. Bloomery process [ ]. Main article: Wrought iron was originally produced by a variety of smelting processes, all described today as 'bloomeries'. Different forms of bloomery were used at different places and times.

The bloomery was charged with and iron ore and then lit. Air was blown in through a to heat the bloomery to a temperature somewhat below the melting point of iron. In the course of the smelt, slag would melt and run out, and from the charcoal would reduce the ore to iron, which formed a spongy mass (called a 'bloom') containing iron and also molten silicate minerals (slag) from the ore. The iron remained in the solid state. If the bloomery were allowed to become hot enough to melt the iron, carbon would dissolve into it and form pig or cast iron, but that was not the intention. However, the design of a bloomery made it difficult to reach the melting point of iron and also prevented the concentration of carbon monoxide from becoming high.

After smelting was complete, the bloom was removed, and the process could then be started again. It was thus a batch process, rather than a continuous one such as a blast furnace. The bloom had to be forged mechanically to consolidate it and shape it into a bar, expelling slag in the process. During the, water-power was applied to the process, probably initially for powering bellows, and only later to hammers for forging the blooms. However, while it is certain that water-power was used, the details remain uncertain. That was the culmination of the direct process of ironmaking. It survived in and southern as Catalan Forges to the mid 19th century, in as the stuckofen to 1775, and near in England until about 1770; it was still in use with in in the 1880s.

Diamond Nikifa Kesho Free Download Mp3. In the last of the old bloomeries used in production of traditional steel, mainly used in swordmaking, was extinguished only in 1925, though in the late 20th century the production resumed on a low scale to supply the steel to the artisan swordmakers. Osmond process [ ].

Main article: In the 15th century, the blast furnace spread into what is now where it was improved. From there, it spread via the on the boundary of and then to the in England. With it, the finery forge spread. Those remelted the pig iron and (in effect) burnt out the carbon, producing a bloom, which was then forged into a bar iron. If rod iron was required, a slitting mill was used.

The finery process existed in two slightly different forms. In Great Britain, France, and parts of Sweden, only the Walloon process was used. That employed two different hearths, a finery hearth for finishing the iron and a chafery hearth for reheating it in the course of drawing the bloom out into a bar. The finery always burnt charcoal, but the chafery could be fired with mineral, since its impurities would not harm the iron when it was in the solid state.

On the other hand, the German process, used in Germany, Russia, and most of Sweden used a single hearth for all stages. The introduction of for use in the blast furnace by in 1709 (or perhaps others a little earlier) initially had little effect on wrought iron production. Only in the 1750s was coke pig iron used on any significant scale as the feedstock of finery forges. However, charcoal continued to be the fuel for the finery. Potting and stamping [ ] From the late 1750s, ironmasters began to develop processes for making bar iron without charcoal.

There were a number of patented processes for that, which are referred to today as. The earliest were developed by John Wood of and his brother Charles Wood of Low Mill at, patented in 1763. Another was developed for the Company by the. Another important one was that of John Wright and Joseph Jesson of. Puddling process [ ].

Main article: A number of processes for making wrought iron without charcoal were devised as the began during the latter half of the 18th century. The most successful of those was puddling, using a puddling furnace (a variety of the ), which was invented by in 1784. It was later improved by others including, who was the first to add iron oxide to the charge. In that type of furnace, the metal does not come into contact with the fuel, and so is not contaminated by its impurities. The heat of the combustion products pass over the surface of the puddle and the roof of the furnace reverberates (reflects) the heat onto the metal puddle on the fire bridge of the furnace. Unless the raw material used is white cast iron, the pig iron or other raw product of the puddling first had to be refined into, or finers metal. That would be done in a refinery where raw coal was used to remove and convert carbon within the raw material, found in the form of graphite, to a combination with iron called cementite.

In the fully developed process (of Hall), this metal was placed into the hearth of the puddling furnace where it was melted. The hearth was lined with oxidizing agents such as and iron oxide. The mixture was subjected to a strong current of air and stirred with long bars, called puddling bars or rabbles, through working doors. The air, the stirring, and the 'boiling' action of the metal helped the oxidizing agents to oxidize the impurities and carbon out of the pig iron. As the impurities oxidize, they formed a molten slag or drifted off as gas while the retaining iron solidified into spongy wrought iron that floated to the top of the puddle and were fished out of the melt as puddle balls using puddle bars.

Shingling [ ]. Main article: There was still some slag left in the puddle balls, so while they were still hot they would be shingled to remove the remaining slag and cinder. That was achieved by forging the balls under a hammer, or by squeezing the bloom in a machine. The material obtained at the end of shingling is known as bloom. The blooms are not useful in that form, so they were rolled into a final product.

Sometimes European ironworks would skip the shingling process completely and roll the puddle balls. The only drawback to that is that the edges of the rough bars were not as well compressed. When the rough bar was reheated, the edges might separate and be lost into the furnace. Main article: The bloom was passed through rollers and to produce bars. The bars of wrought iron were of poor quality, called muck bars or puddle bars. To improve their quality, the bars were cut up, piled and tied together by wires, a process known as or piling.

They were then reheated and rolled again in merchant rolls. The process could be repeated several times to produce wrought iron of desired quality. Wrought iron that has been rolled multiple times is called merchant bar or merchant iron. Lancashire process [ ]. Main article: The advantage of puddling was that it used coal, not charcoal as fuel. However, that was of little advantage in Sweden, which lacked coal. Observed charcoal fineries at, which were quite different from any in Sweden.

After his return to Sweden in the 1830s, he experimented and developed a process similar to puddling but used firewood and charcoal, which was widely adopted in the in the following decades. Aston process [ ] In 1925, James Aston of the developed a process for manufacturing wrought iron quickly and economically. It involved taking molten steel from a and pouring it into cooler liquid slag. The temperature of the steel is about 1500 °C and the liquid slag is maintained at approximately 1200 °C. The molten steel contains a large amount of dissolved gases so when the liquid steel hit the cooler surfaces of the liquid slag the gases were liberated.

The molten steel then froze to yield a spongy mass having a temperature of about 1370 °C. The spongy mass would then be finished by being and as described under puddling (above).

Three to four tons could be converted per batch with the method. Decline [ ] began to replace iron for railroad rails as soon as the for its manufacture was adopted (1865 on). Iron remained dominant for structural applications until the 1880s, because of problems with brittle steel, caused by introduced nitrogen, high carbon, excess phosphorus, or excessive temperature during or too-rapid rolling. By 1890 steel had largely replaced iron for structural applications. Sheet iron (Armco 99.97% pure iron) had good properties for use in appliances, being well-suited for enamelling and welding, and rust-resistant. In the 1960s, the price of steel production was dropping due to recycling, and even using the Aston process, wrought iron production was labor-intensive. It has been estimated that the production of wrought iron costs approximately twice as much as that of low-carbon steel.

In the United States the last plant closed in 1969. The last in the world was the Atlas Forge of in, Great Britain, which closed in 1973. Its 1860s-era equipment was moved to the of for preservation. Some wrought iron is still being produced for heritage restoration purposes, but only by recycling scrap. Properties [ ]. The microstructure of wrought iron, showing dark slag inclusions in The slag inclusions, or, in wrought iron give it properties not found in other forms of ferrous metal. There are approximately 250,000 inclusions per square inch.

A fresh fracture shows a clear bluish color with a high silky luster and fibrous appearance. Wrought iron lacks the carbon content necessary for hardening through, but in areas where steel was uncommon or unknown, tools were sometimes cold-worked (hence ) in order to harden them. An advantage of its low carbon content is its excellent weldability. Furthermore, sheet wrought iron cannot bend as much as steel sheet metal (when cold worked).

Wrought iron can be melted and cast, however the product is no longer wrought iron, since the slag stringers characteristic of wrought iron disappear on melting, so the product resembles impure cast Bessemer steel. Asterix Und Obelix Streit Um Gallien Kostenlos more. There is no engineering advantage as compared to cast iron or steel, both of which are cheaper. Due to the variations in iron ore origin and iron manufacture, wrought iron can be inferior or superior in corrosion resistance compared to other iron alloys.

There are many mechanisms behind that corrosion resistance. Chilton and Evans found that nickel enrichment bands reduce corrosion. They also found that in puddled, forged and piled iron, the working-over of the metal spread out copper, nickel and tin impurities, which produces electrochemical conditions that slow down corrosion. The slag inclusions have been shown to disperse corrosion to an even film, enabling the iron to resist pitting. Another study has shown that slag inclusions are pathways to corrosion. Other studies show that sulfur impurities in the wrought iron decrease corrosion resistance, but phosphorus increase corrosion resistance. Environments with a high concentration of chlorine ions also decreases wrought iron's corrosion resistance.

Wrought iron may be welded in the same manner as mild steel, but the presence of oxide or will give defective results. The material has a rough surface, so it can hold platings and coatings better. For instance, a galvanic zinc finish applied to wrought iron is approximately 25–40% thicker than the same finish on steel. In Table 1, the chemical composition of wrought iron is compared to that of pig iron and. Although it appears that wrought iron and plain carbon steel have similar chemical compositions, that is deceiving. Most of the manganese, sulfur, phosphorus, and silicon are incorporated into the slag fibers present in the wrought iron, so, really, wrought iron is purer than plain carbon steel.