Passive Region
Potential range in a polarization curve where a metal is protected from rapid dissolution by a surface film despite thermodynamically unstable conditions. The corrosion rate remains at a very low level here.
The passivation range is the condition in which a protective oxide layer forms on the metal surface. You absolutely have to keep an eye on this when welding. If you destroy the layer through excessive heat or improper treatment, the part will rust away faster than you'd like. Especially when welding stainless materials, you must not introduce too much heat into the component. Otherwise, you'll burn the alloy and ruin the corrosion protection. After welding, it helps to clean and pickle the weld so that the protective layer can build up again properly. Make sure you don't contaminate the surface with foreign particles like grinding dust from regular steel. That causes rust pitting. If you follow the basic rules and treat the weld cleanly afterwards, the component stays tight and durable.