Automatic Welding of High Carbon Hoop Steels

Abstract

At Chita Plant of Daido Steel Co. the butt welding of hoop steels, as the preparatory process, is being done aiming at improvement of efficiency and yield of cold rolling work of hoop steels.The welding has been done manually up to now under TIG method, but the raw material was such a high carbon steel whose weldability was poor and therefore, it was inclined to grow weld defects and there occured breaking accident very often around the weld zone during rolling.Therefore, we have made an investigate on automation of welding for the purpose of quality stabilization of weld zone.Considering that the part to be welded is, before rolling, to be made smooth after removing the reinforcement, the thickness of plate for welding, the most positive trial of making the weld zone into product, the processing at Chita Plant etc. We have come to adopt TIG method without using filler metal.If the plate thickness is up to 4.2mm the automation of a one side welding of I-butt by Ar or Ar plus H2 atmosphere is possible. For the plate thicker than the above mentioned, the double side welding method whose first pass is flat position is preferable.The above written method is now being tried experimentally at present and our purpose seems to be achieved efficiently.