Kinetics of the Hydrogen Desorption and Absorption of Molten Steel

Abstract

The rate of hydrogen absorption in liquid steel heated by an electric resistance furnace was measured by using an entirely different method from the conventional Sieverts' method or sampling method.
The experimental conditions were selected not to be influenced by flow rates and the composition of carrier-gas, and the depth of immersion pipe into the melt. The values of apparent mass transfer coefficients of hydrogen in liquid steel, which were obtained from the desorption process, are as follows;
k_m=1.04×10^-2cm/sec at 1580°C
k_m=0.98×10-2cm/sec at 1550°C
The possible rate controlling step for absorption and desorption stages was discussed, and the results are summerized as follows;
1) The rate of hydrogen absorption into liquid steel is controlled by chemical reaction at the steel-gas interface.
2) The rate of hydrogen desorption is controlled by the mass transfer of hydrogen atoms in the boundary layer of liquid steel, and the activation energy is approximately 7 kcal/mol, which nearly agrees with the order of activation energy of diffusion of hydrogen in liquid steel.