A considerable body of technical literature makes it possible to follow changes in nitrogen dissolved in molten cast iron (N) through various steps in melting and pouring processes. Melting superheat temperature; melting furnace type, whether cupola, line frequency electric, or arc me a variety of holding furnace types; pouring temperature; and final solidification all have an impact on the dissolved N level in the iron at each stage. Dissolved N{sub}2 may come from atmospheric N{sub}2 charge materials, ferroalloys and inoculants, carbon raisers, and molds and core materials. Steel in the charge is recognized as a major contributor, especially in cupola charges. The equilibrium levels of N in cast iron are quantitatively related to temperatures, %C and %Si through an equation obtained experimentally and thermodynamically. The course of N{sub}2 concentration change is followed with the equation in all processing steps from superheating to solidification. Cupola and arc melting are shown to produce the highest final N{sub}2, and line-frequency electric melting is the lowest. Iron in holding furnaces decreases in dissolved N{sub}2. These effects persist in malleable, gray and ductile irons. Effects of nitrogen in iron on gas hole defects, carbidic solidification, tensile properties and heat treatment are discussed. The role of titanium interaction with N{sub}2 is reviewed.
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