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.
Heat treating
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Heat treating is a group of industrial, thermal and metalworking processes used to alter the physical, and sometimes chemical properties of a material. The most common application is metallurgical. He
Tempering (metallurgy)
…Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloy. The reduction…
Heat treating furnace at 1,800 °F (980 °C)
Photomicrographs of steel. Top: In annealed (slowly cooled) steel, the carbon precipitates forming layers of ferrite (iron) and cementite (carbide). Bottom: In quenched (quickly cooled) steel, the carbon remains trapped in the iron, creating great internal stresses in the needle or plate-like grains.
Hypereutectoid steel
Steel castings after undergoing 12-hour 1,200 °C (2,190 °F) heat treatment.