Nitrogen Binding
Nitrogen binding refers to the capture of dissolved nitrogen in the weld pool by nitride formers such as aluminum or titanium. This prevents embrittlement and aging of the steel.
Physical-Chemical Mechanism of Action
Nitrogen binding occurs when nitride formers come into contact with the molten weld pool. They react with dissolved nitrogen and form nitrides that adhere firmly to the metal grain boundaries.
Metallurgical Relevance & Welding Risks
Without nitrogen binding, dissolved nitrogen can consolidate in the weld zone and lead to embrittlement. This can impair the strength of the weld and cause cracking. Additionally, the steel can become more susceptible to corrosion.
Workshop Practice & Instructions
Use nitride formers like aluminum or titanium in the weld zone to ensure nitrogen binding. The concentration of nitride formers should be chosen so that it can keep the nitrogen content in the molten weld pool below 10 ppm. This prevents embrittlement and increases the service life of the weld.