This operation gives specific shapes and dimensions to materials, exploiting their plastic properties when they are heated.
The aptitude of a material to plastic processing is called formability, it concerns not only the ability of the material to deform without breakage, but also the extent of resistance that the material opposes to deformation.
Formability depends on metallurgical factors: crystal structure, composition, purity, grain size, applied forces and temperature.
The temperature, acting on both the plasticity and the resistance to deformation of the material, greatly affects the degree of formability.
Hot forging is simply the high-temperature plastic transformation of a solid steel by compressing it between two moulds to achieve a desired shape.