Critical degree of deformation
A small degree of deformation that causes undesirable extreme grain growth during subsequent annealing. Below this threshold, no recrystallization occurs.
Watch out with cold forming if you anneal afterwards. If the deformation is in a critical range, e.g. from straightening or bending, then only a few grains grow during annealing and you get a coarse grain. That makes the part brittle and the notch impact energy drops, especially in the weld area. If you have to straighten something and it will be annealed afterwards, do it warm. If you straighten cold, make sure you either only go lightly or pull it through properly – the critical range in between is taboo. Once the part is deformed in that range, you must not stress-relief anneal it. If in doubt, check the structure at that spot.