Hmogenisation is the practice of heating ingots to a high temperature prior to rolling (often termed “preheating”) to ensure the ingot is at a constant temperature throughout, and to modify the microstructure to both improve rollability and develop the correct properties at final gauge.

Various microstructural changes occur in 3xxx alloys as follows -

• dissolution of some as - cast intermetallic phases and redistribution of solute
• nucleation, growth and coarsening of small precipitates from the as-cast supersaturated solid solution, known as “dispersoids”
• transformation of some intermetallic phases.

The practice may be carried out in either large air circulating furnaces, often called “soaking pits”, or in more modern pusher furnaces which are more attractive due to the higher heating rates and consequent shorter homogenisation times.