ABSTRACT
Metals are made of crystals known as grains. The physical properties of metals are affected partly by the size and shape of the grains. For example, by hammering bronze, the grains are flattened, thereby giving a stronger but more brittle material. Subsequent heating, known as annealing, may produce smaller equiaxial grains which contain a degree of the increased strength and a loss of some of the brittleness. This change occurs at the recrystallization temperature which for bronze is in the region of 600°C, whilst for lead it is as low as normal room temperature.
