Alloy Homogenization
Thermal diffusion process to reduce concentration gradients and dendritic segregation in the as-cast state prior to hot working. This achieves a uniform distribution of alloying elements throughout the microstructure.
Homogenizing means: the structure should balance out after casting or forging. Through heat and holding time, the alloying elements migrate and compensate for the differences that formed during solidification – the so-called segregations. If you don't do this, you'll have zones with different hardness and strength. That will get back at you during welding: the weld can pick up what the base material can't tolerate, and you'll get cracks or a brittle, glass-hard structure. So: before welding, anneal the part properly so the structure becomes calm and uniform. The exact temperature and time depend on the material – you have to check the data sheet, not guess.