The history of the heat treatment of steel ball: in 1863, the British metallographer and geologists showed six different microstructure of steel under a microscope, which proved that during heating and cooling, there will be an organizational change in steel, the steel at a high-temperature phase in the quenched into a hard phase. Allotropic Frenchman Osmond established the theory of iron, and the British Austen first formulated the iron-carbon phase diagram. The above two creations initially lay the theoretical foundation for the modern heat-treatment process. At the same time, people also study the protection methods of metal in the heating process of metal heat treatment, in order to avoid metal’s oxidation and decarburization in the heating process.
From 1850 to 1880, there had a series of patents for the application of various gases (such as hydrogen, carbon monoxide gas, etc.) to protect the heating. From 1889 to 1890 the British Lake accessed the patent of the bright heat treatment of a variety of metal.
Since the twentieth Century, the development of metal physics and the transplantation application of other new technologies make the metal heat treatment process get greater development. A significant development was in 1901 ~ 1925, application of gas carburizing rotary furnace in industrial production; in 1930s dew point potential difference meter appeared, which can control the carbon potential of the furnace atmosphere, and later people developed ways to further control the carbon potential atmosphere furnace using carbon dioxide infrared instrument; in 1960s heat treatment technology made the use of plasma field and developed ion nitriding, carburizing process; the application of laser and electron beam technology made the metal gained new surface heat treatment and chemical heat treatment method.
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