In the16th century, German tin miners found an annoying substance they nicknamed 'wolffram,' in some tin ores. This reduced the tin yield during smelting. This was first reported by Georgius Agricola in 1546, but when Axel Frederik Cronstedt found it in an iron ore mine in Sweden in 1757, he used the Swedish word for heavy (Tung) and stone (Sten) to make the name 'tungsten.' The element was later designated by the letter W.
In 1781, Swedish chemist Carl Wilhelm Scheele published the results of his experiments on tungsten but it was almost 100 years before tungsten carbide was used in industry. Tungsten filament light bulbs revolutionized the lighting market in 1904.
Robert Mushet invented the first high speed steel (HSS) in 1868. His Special (or Tungsten) tool steel did not have to be quenched to harden it. The steel alloy typically contained 9% tungsten, 2.5% manganese, and 1.85% carbon. Mushet steel was used mainly for machine cutting tools. It was harder than standard water-quenched steel and retained its hardness even at high temperatures so it could would cut faster than carbon steel tools and needed re-grinding less often.
Tungsten carbide, a compound of tungsten and carbon, became one of the most useful cutting materials for machining a variety of metals. (Tungsten carbide is approximately twice as stiff as steel, and is double the density of steel, midway between that of lead and gold. The melting point is over 3000 °C. It's hardness is comparable with corundum (Al2O3, aluminum oxide) and it must be finished and polished with harder abrasives such as cubic boron nitride or diamond powder).
Chromium-vanadium steel alloys incorporating carbon (0.50%), manganese (0.70-0.90%), silicon (0.30%), chromium (0.80-1.10%), and vanadium (0.18%) can be used as high-speed steel. Chromium and vanadium both make the steel more hardenable. Chromium also helps resist abrasion, oxidation, and corrosion and both chromium and carbon can improve elasticity.
The Open Hearth Process, was developed in the 1860s by German engineer Karl Wilhelm Siemens to make steel from cast iron. It was a large shallow furnace heated from brick chambers below the hearth. The high temperature burnt off excess carbon and other impurities and permitted up to 100 metric tons of steel to be produced in one furnace. Scrap steel could be used as a raw material and the steel could be tested periodically. Although much slower, by 1900, it had largely replaced the Bessemer process.
In a later development, called a regenerative furnace, the amount of coke required to produce a ton of steel was reduced considerably by using the waste heat from the furnace to heat the air entering the furnace via recuperator chambers.
(Coke is made by baking coal to removed gases and liquids). A series of innovations made cheaper and better quality steel in the late 19th century and many investors including Andrew Carnegie and Charles Schwab, made huge fortunes meeting the needs for ship building and the rapidly expanding rail roads. Carnegie's US Steel Corporation, founded in 1901, was the first corporation valued at over one billion dollars when it became a publicly traded stock company.
Paul Héroult (co-inventor of the electrolytic method for the production of aluminum) also invented the electric arc furnace (EAF) for steel in 1900. This passed an electric current through the furnace raising temperatures up to 1800°C (3270°F), well above the melting point of iron and steel. EAF's gradually replaced the giant (and more expensive) smelters for iron and steel production and currently produce about 30% of world steel production.
About two thirds of world production is now produced in basic oxygen furnaces which blow pure oxygen into as much as 350 metric tons of molten iron and scrap steel and can convert a charge into steel in less than one hour, far quicker than open-hearth methods. The last open-hearth furnace in the USA closed in 1992.
Basic oxygen furnaces were made possible with the development of the industrial scale separation of atmospheric oxygen from nitrogen in the 1960s. (About 78 per cent of the air we breath is nitrogen and 21 per cent is oxygen and they can be separated by liquefying the air.
Air is filtered to remove dust, and then cooled in stages to -200 °C. First, water vapour condenses and carbon dioxide freezes at -79°C and both are removed. Oxygen liquefies at -183°C and nitrogen liquefies at -196°C and the mixed liquids are moved to a fractional distillation tank. The liquid oxygen settles to the bottom of the tank at -185 °C while the nitrogen rises to the top at -190 °C where is removed as a gas).
Typical tensile strengths of steel
Material Yield strength Ultimate tensile strength (UTS)
(Mpa) (Mpa)
Cast iron 246 414
ASTM A36 steel 250 400–550
1090 mild steel 247 841
Chromium-vanadium
steel 620 940
Steel, AISI 4130,
water quenched 980 1110
Steel, ASTM A514 770 1040
350 Maraging steel 2300 2420
(2420 Mpa = 350,900 psi = 156 tons/sq.in)
350 Maraging steel contains 18% Ni, 12% Co, 5% Mo, 1.5% Ti
1 Mpa (mega Pascal) = 145 psi (pounds/square inch)
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Engineering
Non-FictionDenis Papin built the first steam engine in 1705 and, by 1800, Boulton and Watt had built 451steam engines. In 1870, the British produced 4 million tons of coke for iron and steel production and locomotive and industrial engines. Axel Cronstedt ide...
