Effect of Boron Micro-alloying on the Surface Tension of Liquid Iron and Steel Alloys

Thermo-physical properties of the liquid metals and alloys play an essential role in modeling and controlling metallurgical processes. In particular, surface tension of metals has a strong impact on wetting various surfaces. Boron is added in numerous iron-based alloys as micro-alloying component. In existing literature, there is no general agreement with the effect of boron on the surface tension. The present study focuses on investigations of boron micro-alloying on the surface tension of iron and CrMnNi alloys by the maximum bubble pressure method (MBP). In contrast to other techniques, maximum bubble pressure technique is less affected by the evaporation of surface-active elements and the purity of the atmosphere around the sample. Measurement of the surface tension was accomplished before and after in situ addition of boron to the molten metal phase. Samples were molten in ZrO2 and Al2O3 crucibles and yttria-PSZ capillaries were used for the experiments. Measurements were carried out at 1550 degrees C in argon atmosphere and argon as bubbles formation media. Results of the experiments indicate a minor effect of boron on the surface tension of liquid iron. Effect of boron on the surface tension of steels is discussed in the context of other surface-active elements present.