The denitrogenation behaviour during vacuum induction melting of Ni base superalloy using CaO crucible was studied, and the nitrogen solubility under different vacuum levels as well as Al and Ti addition amounts at 1873 K were also calculated. The experiment results show that Al addition had bene® cial effect, but Ti addition had adverse effect to denitrogenation. The increase of vacuum level is a powerful measure to accelerate the denitrogenation process. The denitrogenation mechanism has been discussed for a nitrogen content of below 10 ppm. MST/5046

The denitrogenation technology and mechanism of a new kind of Ni-base superalloy during vacuum induction melting (VIM) were studied. The nitrogen content could be reduced from 0.0005% to 0.0002% by this technology. The calculated interaction coefficient of Ti with N () is about -0.38, and the activity coefficient of N () is 0.714. The denitrogenation mechanism was discussed through the calculation of the reaction ratio constants and .

In modern society, due to the improvement of industrialized and development of marine economy, pollutants in the atmosphere and water aggravation corrosion of steel structure, annual worldwide economic losses due to corrosion is astronomical figures. Hence, atmospheric corrosion resistance of weathering steel has a broad market prospect. In addition, it also has excellent mechanics, welding and other properties. This paper mainly discusses the structure, production process, performance organization and the effect of various alloying elements on weathering steel.

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