A phenomenon that occurs during the cooling of iron and other ferromagnetic metals after they have been heated. When iron is heated to white heat and then allowed to cool, it abruptly evolves heat at a certain temperature. This evolution of heat, which slows down the cooling process and can lead to a brief reheating, is caused by an exothermic reaction when the structure of the crystal changes. The temperature at which this occurs is called the recalescence point. For pure iron there are two recalescence points: at 780°C and 880°C. A reverse phenomenon causing cooling, called decalescence, occurs when ferromagnetic metals are heated.