Welding steel or aluminium plates - using metal-inert gas combined with hot wire process for heavy root passes

摘要

The inert gas welding process is esp. for joining thick plates using seam-edge prepn. and a root welding pass followed by a filling pass or passes, the novelty being that the root pass is made by metal inert gas welding (MIG) using high current and the filling pass(es) made by the hot wire process. The hot wire pref. follows the MIG electrode wire, using the same molten bath, the MIG wire using a current density above 250 A/mm2 of the wire cross-section and a wire dia. of 0.8-2.4mm. Alternatively, an MIG wire of 1.6-4.0mm may be used with a current of 400-900 amps. The MIG- or the hot wire electrode may be cored. The term hot wire means the use of a wire carrying A;C. or D.C. where the wire is permanently immersed in the molten metal and melted primarily by resistance heating. Used for container and ship welding of steel plate 5-50mm thick, also Al plate. Avoids submerged arc-welding, tack welding, the use of a pad under the seam, and turning the plates over; the process can be applied by machine.