Duplex Nitrogen Alloying
Duplex nitrogen alloying stabilizes austenite and increases pitting corrosion resistance and yield strength through targeted nitrogen addition.
Physico-Chemical Mechanism of Action
Nitrogen is added to duplex steels as an austenite stabilizer. It prevents the transformation of austenite into ferrite and martensite by influencing the kinetics of phase transformations.
Metallurgical Relevance & Welding Risks
Targeted nitrogen addition increases the pitting corrosion resistance and yield strength of the material. Missing or too little nitrogen leads to ferrite oversaturation in the heat-affected zone, resulting in low toughness and increased risk of cracking.
Workshop Practice & Instructions
When welding duplex steels with nitrogen alloying, careful control of temperature and cooling method is crucial. Use a stable welding process to minimize the heat-affected zone. Too rapid cooling can lead to ferrite oversaturation, while too slow cooling can result in martensite formation and increased risk of cracking.