Penetration

Penetration is the area at the base material that is melted during welding. How deep it is depends on current, speed, and arc. If you have too much penetration, you burn the material and the structure suffers – that causes cracks or distortion. So make sure you don't stay too long in one spot and that penetration runs clean and even. If you notice the pool sinking too deep or getting too wide, turn down or go faster.