Effect of carbon on nitrogen solubility and AlN formation in high Al alloyed liquid steels

Abstract

The nitrogen solubility and the AlN solubility product in liquid Fe-C-Al-N alloys containing a wide composition range of carbon and aluminum were measured in the temperature range of 1 773-1 873 K. Aluminum and carbon both decreased the nitrogen solubility in liquid iron. The simultaneous effect of aluminum and carbon on nitrogen solubility in liquid iron was determined. The AlN solubility product in liquid iron decreased significantly with carbon addition primarily due to the large effect of carbon on nitrogen solubility. Using the Wagner's formalism, the experimental results were thermodynamically analyzed to determine the interaction parameters among carbon, aluminum and nitrogen in liquid iron as follows: rNC, Al = 0.038 ± 0.0006 ([C] : 0.39 - 2.03 mass%, [Al] ≤ 0.91 mass%,1 773 -1 873 K) e AlC = 0.03 ± 0.0005, rAlC = 0 ([C] ≤ 3.9 mass%, [Al] : 1.2 - 2.45mass%, 1 773 -1 873 K) © 2014 ISIJ.