Nitrogen Solubility in Liquid Fe–C Alloys

Abstract

The nitrogen solubility in liquid Fe-C alloys containing carbon up to 5.2 mass% has been measured under reduced nitrogen partial pressures in the temperature range of 1 773-1 873 K. Previous studies on the C-N interaction in liquid iron have shown marked disagreement on its temperature dependency and the order of interaction. By the gas-liquid metal equilibration technique using a high frequency induction furnace with an accurate temperature measurement, precise nitrogen solubility data were obtained. The interaction between carbon and nitrogen in liquid iron has been expressed in terms of the first-and second-order interaction parameters. No temperature dependence of these values was observed in the temperature range from 1 773 to 1 873 K.(1.14 ≤ mass% C ≤ 4.95 at 1 773 K, 0 ≤ mass% C ≤ 5.2 at 1 823-1 873 K) KEY WORDS: nitrogen solubility; Fe-C alloy; carbon; interaction parameter.

Effect of Carbon on Nitrogen Solubility and AlN Formation in High Al Alloyed Liquid Steels

“…Detailed descriptions of the experimental apparatus and procedure are available in the authors' recent studies. [10][11][12] Five hundred grams of high purity electrolytic iron or Fe-C alloys contained in an Al 2 O 3 crucible (outer diameter (OD): 56 mm, inner diameter (ID): 50 mm, height (H): 96 mm) was melted in the temperature range from 1 773 to 1 873 K by a 15 kW/30 kHz high frequency induction furnace. After melting the iron, the melt temperature was directly measured by a Pt/Pt-13 mass%Rh thermocouple sheathed with an 8 mm OD alumina tube immersed in the melt.…”

“…In the authors' recent studies, the thermodynamics of nitrogen and AlN formation in Fe-Al-N melt, 11) and the interaction parameter of carbon on nitrogen in Fe-C-N melt 12) were determined. Thermodynamic parameters used in the present study are summarized in Table 2.…”

“…9) The thermodynamics of aluminum, nitrogen and AlN formation in liquid Fe-Al-N alloy is available in the authors' recent studies, 10,11) and the effect of carbon on the nitrogen solubility in liquid Fe-C-N alloy is extensively studied by various authors. [12][13][14][15][16][17][18][19][20] However, the effect of carbon on AlN formation and the simultaneous effect of carbon and aluminum on nitrogen solubility in liquid Fe-C-Al-N alloy are not known yet.…”

Thermodynamics of Nitrogen Solubility and AlN Formation in Multi-Component High Mn Steel Melts

“…7) In Fe-Mn-N and Fe-Si-N systems, it was not clear about the second-order effect of Mn and Si on N solubility at high concentration region. 11,15) Moreover, the cross-product effect of those alloying elements on N solubility in multi-component systems has been studied much.…”

“…However, most of the available data have been measured at the limited ranges of alloying concentration and temperature. In the authors' recent studies, 5,7,8) it was found that the second-order effect of alloying elements on N in liquid iron was necessary for the accurate prediction of the N solubility in high alloy steels. Also, the secondorder cross-product effect on N in liquid iron significantly affected the accuracy of both N solubility and AlN solubility product in multi-component alloy systems.…”