Incubation Period of Age Hardening

Incubation time is the time the material needs after welding before hardening really kicks in. If you don't respect it, the structure gets too hard and you get cracks, especially with quenched and tempered or alloyed steels. So make sure you don't cool the part too quickly after welding, but give it the time it needs. For critical steels, controlled cooling is key, otherwise you'll quickly have a warped or cracked weld.