Tempering (metallurgy)
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Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys.
Differentially tempered steel. The various colors produced indicate the temperature the steel was heated to. Light straw indicates 204 °C (399 °F) and light blue indicates 337 °C (639 °F).
Photomicrograph of martensite, a very hard microstructure formed when steel is quenched. Tempering reduces the hardness in the martensite by transforming it into various forms of tempered martensite.
Pieces of through-tempered steel flatbar. The first one, on the left, is normalized steel. The second is quenched, untempered martensite. The remaining pieces have been tempered in an oven to their corresponding temperature, for an hour each. "Tempering standards" like these are sometimes used by blacksmiths for comparison, ensuring that the work is tempered to the proper color.
A differentially tempered sword. The center is tempered to a springy hardness while the edges are tempered slightly harder than a hammer.
Quenching
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In materials science, quenching is the rapid cooling of a workpiece in water, gas, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating, quenching prevents
Tempering (metallurgy)
…in hardness is usually accompanied by an increase in ductility, thereby decreasing the brittleness of the metal. Tempering is usually performed after quenching, which is rapid cooling of the metal to put it in its hardest state. Tempering is accomplished by controlled heating of the quenched workpiece to a…
Coke being pushed into a quenching car, Hanna furnaces of the Great Lakes Steel Corporation, Detroit, Michigan, November 1942
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