Nitrogen Absorption Behavior
Nitrogen pickup behavior describes how nitrogen from the environment is absorbed into the weld matrix. This can lead to porosity and embrittlement.
Physicochemical mechanism of action
Nitrogen pickup refers to the process where nitrogen from the surrounding gas atmosphere is absorbed into the liquid or glowing metal matrix. This can happen through diffusion and adsorption. With a high nitrogen content in the atmosphere, the nitrogen pickup can increase.
Metallurgical relevance & risks in welding
Nitrogen pickup has a significant impact on weld quality. It can cause porosity because the absorbed nitrogen remains as gas in the melt matrix and escapes as gas during cooling. Additionally, it can lead to embrittlement of the structure, reducing the hardness and toughness of the weld. This can cause cracks and other mechanical defects in the material.
Workshop practice & instructions
To minimize nitrogen pickup, the following measures should be taken:
• Use shielding gases like argon or helium in the welding atmosphere.
• Ensure that the uptake of nitrogen from the environment is limited by restricting drafts in the work area.
• Choose suitable welding processes and parameter settings that reduce nitrogen pickup.