Titanium Grades Corrosion Behavior
The excellent resistance of technical titanium alloys in oxidizing media through the spontaneous formation of a passive titanium dioxide layer. It offers protection even in highly chloride-containing environments.
Titanium immediately forms a hard, dense oxide layer on contact with air, which protects it from corrosion. When welding, you absolutely have to keep an eye on this layer: as soon as the material gets hot and comes into contact with oxygen, it attracts nitrogen and oxygen from the air and becomes brittle and fragile. That's why the trailing shield gas when welding is the be-all and end-all – you have to cover the weld and the heat-affected zone with argon until the material has cooled down significantly. If the weld turns blue or gray, too much oxygen got to it and the weld is ruined.