Grain non-uniformity means that some parts of the forgings are particularly coarse, while others are smaller.

The main reason for the uneven grain size is that the uneven deformation of the billet causes different degrees of grain breakage, or the deformation degree of the local area falls into the critical deformation zone, or the local work hardening of the high-temperature alloy, or the local grains are coarse during quenching and heating.

Heat-resistant steel and high-temperature alloys are particularly sensitive to grain non-uniformity, and uneven grain size will reduce the durability and fatigue performance of forgings.