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A Brief History of Engineering
Published in Diane P. Michelfelder, Neelke Doorn, The Routledge Handbook of the Philosophy of Engineering, 2020
Evidence for connections between iron and authority are stronger than for steel. Iron smelting has been dated back to the second millennium BCE in China and, more recently, the north of what is now Nigeria (Darling 2013). Evidence indicates intensive experimentation in a contained geographic region; early iron was used in both military and agricultural artifacts, and in Nigeria, the working of iron had religious significance. By the fourth century BCE, China was exporting cast iron to Rome and, by the eleventh century, had developed an iron industry centered on smelting households with a variety of official roles in local governments (Arnoux 2004; Wagner 2001). Both Austria and India produced steel by the late first millennium BCE; in the case of India, the famous Wootz steel from which Damascus steel was made. Ingots were carried from India to Damascus to be forged into blades highly prized for distinctive patterns that emerged as the steel was worked. Wootz steel was produced in clay crucibles under high temperatures, and although it required a supporting system of supply of raw materials, fuel, and apparatus, it may well have been produced as a craft rather than engineering tradition. By the early modern era, cast iron had been put to use in cannon in Europe, where it stimulated the development of star-shaped fortifications designed to prevent the new weapons from ever getting a straight shot at a wall.
Iron-Carbon Diagram
Published in P. C. Angelo, B. Ravisankar, Introduction to Steels, 2019
It is well known that steel is an interstitial solid solution (alloy) of iron and carbon and it is more often referred to as a metal and while with subsequent addition of other solutes it is called as alloy steel, though it is a misnomer. Alloy steels are by far the most common industrial metals as they have a great range of desirable properties. Steel, with smaller carbon content than pig iron (about 4 wt.% C) but more than wrought iron (almost a pure iron), was first produced in antiquity by using a bloomery. By 1000 BCE, blacksmiths in Luristan in western Persia were making good steel. The improved versions such as Wootz steel by India and Damascus steel were developed around 300 BCE. These methods were specialized, and so steel did not become a major commodity until 1850s. New methods of producing it by carburizing bars of iron in the cementation process were devised in the 17th century. In the Industrial Revolution, new methods of producing bar iron without charcoal were devised and these were later applied to produce steel. In the late 1850s, Henry Bessemer invented a new steelmaking process, involving blowing air through molten pig iron, to produce mild steel. This made steel much more economical, thereby leading to wrought iron being no longer produced in large quantities. Carbon steels are least expensive of all metals while stainless steels are costly.
What Have We Learnt From the Nature and History?
Published in Rajendra Kumar Goyal, Nanomaterials and Nanocomposites, 2017
For more than 400 years ago, Indians were aware of the importance of wootz steels which were used to produce Damascus swords with high mechanical strength and flexibility. These swords were used as weapons in the battlefield till the nineteenth century against Muslim nations in Europe [24]. The steel of Damascus blades used by Crusaders fighting against Muslims showed a characteristic wavy banding pattern (Figure 4.12a and b) with extraordinary mechanical properties, and an exceptionally sharp cutting edge from the ultrahigh-carbon steel. It is believed that Damascus blades were forged directly from wootz steel produced in ancient India. A sophisticated thermomechanical treatment of forging and annealing was applied to refine the steel to its exceptional quality. Small additions of the alloying elements such as vanadium, chromium, manganese, cobalt, nickel, and others are known to facilitate the formation of cementite (Fe3C) bands during thermal cycling at temperatures below the cementite formation temperature (about 800°C) [25].
Historical overview on the development of converter steelmaking from Bessemer to modern practices and future outlook
Published in Mineral Processing and Extractive Metallurgy, 2019
Early primitive furnaces were of bowl type and often constructed in a hillside to exploit natural draught of air. In more advanced furnaces air blast was generated by bellows. The bloomery process governed iron/steel making technology for the next millennium and beyond, known, e.g. as Catalan hearth (Thomas 1999). In these early furnaces, formation of metallic iron took place in the solid state, and the product had low carbon content. There was no need for converting to decrease carbon content by oxidation. Ancient blacksmiths knew from experience how to decarburise or carbonise to the desired final carbon content in their forge furnaces. In the course of time, larger bloomeries were erected and equipped with efficient water-driven bellows. Then temperature inside the hearth could rise too high leading to carbon dissolution into iron, the melting point was reached and the iron bloom melted. The blast furnace was thus accidentally discovered. Towards the end of the Medieval Age blast furnace technology was gradually established in Europe. In China liquid iron was known much earlier, about 200 BCE and in India somewhat later. Liquid iron could be utilised in castings but it was difficult to convert iron into steel. Effective decarburisation methods were not available until the eighteenth century. To convert liquid cast iron into steel finery methods were developed, like Osmond and German forges, Walloon, Lancashire and Franche-Comté hearths, from the late Middle Ages to the nineteenth century (Wiborgh 1904). These methods were based on melting of pig iron by combusting charcoal and slow decarburisation refining in semi liquid/semi solid state. In the eighteenth century, more efficient refinery methods were developed. The puddling furnace was a kind of reverberatory furnace. Pig iron was melted by flame from a fireplace, where coal or coke was burnt as fuel. After melting the charge, carbon in the molten iron was oxidised by air by stirring the melt with puddling bars. When the carbon content decreased, the iron solidified and it was gathered by the puddler into a single mass, pulled out and worked under a forge hammer, and then the hot wrought iron would be run through rollers. By using the puddling process, it was possible to produce steel in one stage, faster and with less fuel than with the earlier methods. Another process, crucible steelmaking was developed by clockmaker Benjamin Huntsman in 1740. Cold pig iron was charged with slag-forming flux in small crucibles made of clay and graphite, and then melted by combusting coke. Then low carbon steel was added and melted to get liquid high-carbon steel (e.g. 1% C). The product received was hardenable steel and suitable for tools, mechanical parts etc. Crucible steel remained in a strong position for special grades like tool steels until the first half of twentieth century. The aim of the process was actually not in decarburisation but rather in combination of high- and low-carbon metals. The ancient Indian wootz steel was based on a similar principle (Srinivasan and Ranganathan 2004).