Research on controlling method of size and distribution of oxide inclusions in weld metal with auxiliary electric field

For controlling size and distribution of oxide inclusions in weld metal,a method was presented in which an auxiliary electric field was applied between molten slag and weld pool metal with submerged arc welding so as to lead ion flow in molten by making use of auxiliary electric field. The preliminary experimental research was carried out with voltage supplied by direct current power supply as auxiliary electric field. The results show that when tungsten is used as cathode of auxiliary electric field,the electric conductivity of molten slag can be greatly improved due to lots of free electrons running into molten slag,and this makes a steady directional ion flow effectively inside the molten. By making complex particles ionization inside the molten, the auxiliary electric field applied between molten slag and weld pool metal impels both positive and negative ions to produce inverse flowers and results in electrochemical reactions at interface, thus reducing the opportunity of oxidation and this is helpful for inclusions to be broken and homogeneous. Meanwhile, under auxiliary electric field,the free oxygen ion in weld pool will migrate to slag-metal interface and be preferably combined with oxide forming elements in molten slag,then enter into slag. Therefore the oxygen content in weld metal can be effectively reduced.