4.2 Rolling
Process Description
Continuous forming of metal between a set of rotating rolls whose shape or height is adjusted
incrementally to produce desired section through imposing high pressures for plastic deformation.
It is the process of reducing thickness, increasing length without increasing the width
markedly. Can be performed with the material at a high temperature (hot) or initially at
ambient temperature (cold) (Figure 4.2(a)).
Materials
• Most ductile metals such as: low carbon alloy and stainless steels; aluminium alloys;
copper alloys and magnesium alloys.
• Metal ingots called blooms, slabs or billets, used to load the mill. Blooms are used to
produce structural sections (beams, channels, rail sections); slabs are used to produce flat
products such as sheets and plate; and billets are rolled into rods and bars using shaped rolls.
• Continuous casting is also used for higher efficiency and lower cost.
Process Variations
• Variety of roll combinations exist (called mills):
• Two high: commonly used for hot rolling of plate and flat product, either reversing or
non-reversing type.
• Two high with vertical rolls: commonly used for hot rolling of structural sections.
Vertical rolls maintain uniform deformation of section and prevent cracking.