How does rolling the head of a Stick (Ex. Arrow head/Spear) make it Harder?
I have seen videos on Youtube & Instructables about make a Spear/Arrow head stronger, i was wodering if this is due to tempering (Ex. Steel Heating, cooling rapidly for stronger atomic bond) or due to some other method of strengthing I do not know about ( I only know the Steel method due to mass History/Science channel fanatical-ness)
Plase help me uderstand this.