The loss of ductility caused in certain steels when they are held in or slowly cooled through the temperature range 300º to 600ºC.
This effect is commonly seen in nickel–chromium steels and is due to the precipitation of carbides in the areas between the crystals in their structure (grain boundaries). It can be overcome by adding 0.2% to 0.3% molybdenum.
This effect is called temper brittleness since it occurs in the normal tempering range of steels.
See also nitriding.
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