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Alloy Steel

Alloying elements are added to steels in order to improve specific properties such as
strength, wear, and corrosion resistance. Although theories of alloying have been developed, most commercial alloy steels have been developed by an experimental approach with occasional inspired guesses. The first experimental study of alloy additions to steel was made in 1820 by the Britons James Stodart and Michael Faraday, who added gold and silver to steel in an attempt to improve its corrosion resistance. The mixtures were not commercially feasible, but they initiated the idea of adding chromium to steel.The first commercial alloy steel is usually attributed to the Briton Robert F. Mushet, who in 1868 discovered that adding tungsten to steel greatly increased its hardness even after air cooling. This material formed the basis of the subsequent development of tool steels for the machining of metals.The general understanding of why or how alloying elements influenced the depth of hardening—the hardenability—came out of research conducted chiefly in the United States during the 1930s. An understanding of why properties changed on tempering came about in the period 1955–1965, following the use of the transmission electron microscope.

01/12/2009 710-745 710-745 710-745
18/04/2009 1525-1600 1800-1850 1250-1350
17/12/2008 900-1200 900-1200 900-1200
30/10/2008 950 800 820
30/08/2008 1220 1140 1300
30/04/2008 1200 1130 1350
31/12/2007 1021 950 1100

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