Carbide Precipitation Kinetics
The time- and temperature-dependent nucleation and growth rate of carbides during the tempering or heat treatment of steels.
Carbide precipitation is what happens when the carbon in steel precipitates as carbide during cooling or tempering. It ultimately determines the hardness and toughness of the structure. If it happens too fast, the material becomes hard and brittle, and it will crack quickly during welding or in service. If it happens too slowly, the grain remains coarse and the material becomes soft and smears. You can control this via heat treatment by choosing the right temperature and holding time during tempering or stress relief annealing. Too hot or too long makes it soft, too cold or too short makes it hard and crack-prone. It always depends on the steel grade and the desired properties.