Reaction Mechanism of Hydrogen in Electroslag Welding

The reaction mechanism of hydrogen transfer in electroslag welding is presented. The effects of baiscity of flux and water vapour pressure of atmopshere on hydrogen contents of deposited weld metal in copper moulds with electroslag welding using a consumable nozzle have been investigated. It has been found that Sievert's law does not hold in the relation between the hydrogen content of weld metal and water vapour pressure but a linear relation does. This relation may hold under the assumption that the water dissolves in slag as hydroxyl combined with silicate networks and free hydroxyl ions and that only hydroxyl ions react with metal. The partition coefficient and the reaction rate constant of hydrogen is reversely proportional to the basicity of flux. The former is almost same as the value so far reported in electroslag ramelting and the latter is three to nine times as high as that.