Hydrogen permeability of slags containing calcium fluoride

Abstract

To investigate the hydrogen permeability of calcium fluoride used for electroslag remelting (ESR) process, "Gas-slagmetal" osmosis process under argon atmosphere saturated with water vapor at 318 K was used to study the hydrogen permeability of slag containing calcium fluoride. The results indicate that the conventional slag, consisting of 70% CaF 2 and 30% Al 2 O 3 , has the lowest hydrogen permeability. A parameter E H was proposed for evaluation of the hydrogen permeability of slags containing calcium fluoride. The hydrogen permeability decreases with increasing E H to a certain extent. An appropriate choice of slag for the ESR process can be obtained. These results also suggest that the hydrogen pick-up in steel after remelting might be reduced when a slag with low hydrogen permeability is used.

Metallurgical Model of Diffusible Hydrogen and Non-Metallic Slag Inclusions in Underwater Wet Welding of High-Strength Steel

“…log C OH = 12.04 − 32.63Λ + 32.71Λ 2 − 6.62Λ 3 (8) An increase in the basicity index of the slag and hydroxyl capacity can be achieved by adding CaF 2 and cryolite Na 3 AlF 6 , which decrease the melting point, viscosity, hydrogen permeability, and density of the slag system [36][37][38][39][40][41]. The increase in slag basicity and the presence of ion Felevate the solubility of water vapor and promote the ionic binding of the hydrogen atom in OH hydroxyl groups, which leads to a decrease in the content of diffusible hydrogen [42].…”

Application of the chloridizing roasting method for the removal of copper and sulphur from copper slags

“…To characterize the slag phase composition clearly, the original copper slag was reprocessed (Dong et al 2011). It was first remelted in a furnace and then cooled slowly in an atmosphere of N 2 .…”

Experimental Investigation on the Evolution of Hydrogen in Steel during the Electroslag Remelting Process

“…Moreover, many works were performed [12][13][14][15] to investigate the hydrogen pick-up for several slags containing calcium fluoride and the slag with different states including new slag, pre-melted slag and recycling slag. In Mitchell's 16 work, he briefly reviewed the slag components and properties evolving with the electroslag remelting process, and the effects of slag on the hydrogen transfer and inclusion composition control.…”