Steel Alloys
Alloy steels are made of steel combined with other metals such as nickel, chromium, or vanadium. The result of combining the metals is a steel product that has increased hardness, strength, durability, malleability, and resistance to corrosion.
The first alloy was developed by the English physicist Michael Faraday in the 1830s. His experimentation in the area of electromagnetic induction and electrolysis resulted in an iron-chromium alloy. In 1883, English metallurgist Sir Robert Hadfield (1858-1940) invented manganese steel at his father's steelmaking firm. Manganese gave the steel strength and resistance to wear. He also invented silicon steel and other alloy steels. Hadfield erroneously assumed that chromium impaired corrosion resistance, otherwise he might have discovered stainless steel.
An American, Elwood Haynes (1857-1925), developed several steel alloys. In 1881 he invented tungsten chrome steel which retains its strength at high temperatures. A chromium/nickel alloy followed in 1897; in 1900 he introduced one of cobalt/chromium; and in 1911 came stainless steel. Building on Haynes's work, other scientists developed stainless steels. German scientists P. Monnartz and W. Borchers were among the first to realize the usefulness of stainless steels. However, the English metallurgist, Harry Brearly, receives the most credit for developing stainless steel. He accidentally discovered that nickel-chromium steel made a good anti-corrosion alloy when he found a sample of it among a pile of discarded experimental scraps with its shine still intact. In 1912 Brearly proposed that the new alloy be used for naval guns. By 1914 he had proved its usefulness as a material for cutlery and obtained an American patent on it in 1915.
Frederick Mark Becket (1875-1942), a Canadian-American metallurgist, developed the silicon reduction process for the mass production of low-carbon ferroalloys and stainless steels. John A. Mathews of Washington, D. C. participated in the development of permanent magnet and corrosion-resistant steels, inoculated iron and high speed vanadium steels in the early 1900s. Mathews received the Andrew Carnegie Gold Medal for Research for his work. In 1912, German researchers Edward Maurer and Benno Strauss developed the austenitic group of stainless steels which are heat-resistant and shock-resistant, making them attractive for use in cookware and chemical equipment.
All steel and steel alloys are classified according to their carbon and alloyed metal content. A higher carbon content increases the strength of the metal. Low-carbon steels containing carbon percentages of.08 to.15 are used in automobile bodies, containers and tubing. Medium-carbon steels having.15 to.35 per cent carbon is used in railroad equipment, bridge and building frames, ship structures and machine parts. The high-carbon steels,.65 to 1.2 per cent, are used in steel rails, drill bits and cutting tools. In alloy steels, the carbon content generally is very low and acts mainly as an alloying agent. The exception is in superplastic steel alloys developed in 1975. Superplastic steel alloys have 1 to 2.1 percent carbon are hard yet not as brittle as such a high carbon count would indicate. Because they have an ultrafine grain size, about 2 microns, superplastic alloys can be stretched to 11 times their size, and display high wear-resistance.
The characteristics of each alloy depend upon the metal that is added to the steel. Some, like nickel and chromium, impart toughness, heat and corrosion resistance. This alloy is used in axles, gears and bearings, and in most stainless steels. Other metals, like manganese, which is added to all steel, improve its workability, and in higher quantities, increases the alloy's strength. Molybdenum is added for its hardening ability and heat resistance. Tungsten is also used as a heat resistant alloy. Boron adds strength to steel at amounts smaller than other alloys. Only.0005 percent is enough to achieve the desired level of strength and toughness. Steel alloys have allowed many important advancements in modern society and are an essential part of the complex steel production industry.
This is the complete article, containing 628 words
(approx. 2 pages at 300 words per page).
