EFFECT OF MAGNETIC STEERING OF THE ARC ON CLAD QUALITY IN SUBMERGED-ARC STRIP CLADDING

Submerged arc strip cladding is often used when thickness of clad mate rial is required. The productivity of this process has been improved b y the use of higher welding currents and wider strips. The associated problems were arc blow, increased penetration and poor bead characteri stics. Dilution is the parameter that controls almost all qualities of cladding. Magnetic steering reduces penetration, and hence, dilution and arc blow control. Stainless steel cladding on mild steel is often used to impart corrosion resistance. In such situations, the clad qual ity is specified by corrosion resistance, ferrite content and good fus ion between clad metal and base metal. This paper discusses results of an investigation on the effect of an oscillating magnetic field used to steer the arc in submerged arc strip cladding using 60 X 0.5-mm 309 L stainless steel strips, with varying magnetizing flux intensity and dwell time. The resulting test pieces were evaluated for parameters th at imparted the best clad quality and the results indicate the followi ng: 1) Magnetic steering of the arc reduces dilution and corrosion rat e. 2) Magnetic steering of the arc permits use of higher currents for a given dilution level, thus increasing productivity. 3) Clad metal mi crostructures of a desirable type are obtained when the arc is magneti cally steered. 4) Use of 309L strips for single layer cladding appears to be satisfactory since ferrite content lies between 5 to 10% for a variety of welding conditions. 5) The corrosion rate (microns per 24 h ours) is linearly related to the dilution percentage of the clad metal .