TWI Industrial Member Report Summary 544/1996
F J Blunt
Magnetic arc oscillation provides a cheap method for substantially increasing productivity in weld overlay.
There is little evidence in the literature that magnetic arc oscillation has been exploited in surfacing applications, although a system is available for orbital tungsten inert gas (TIG) joints in pipework. Oscillating the arc enables a larger area to be covered by weld metal in a given time, thus increasing productivity. At the same time, the dilution of the weld metal is reduced leading to improved properties in the overlay, and it is possible that in some applications fewer layers would be needed to achieve the metallurgical properties required of the overlay material.
Oscillation can be achieved by mechanically manipulating the welding head, but oscillation of the arc alone is an attractive and cheaper alternative. A simple electromagnet can be attached to the welding torch to produce a magnetic field in the welding direction, which causes the arc to be deflected in the transverse direction. Oscillating this field will sweep the arc from side to side, increasing the width of the weld bead.
This work concentrated on mechanised TIG, metal inert gas (MIG) and plasma transferred arc (PTA) processes. Overlay materials chosen were a typical corrosion resistant alloy and a typical wear resistant alloy, to be deposited on a carbon- manganese steel.
- To demonstrate the suitability of magnetic arc oscillation for TIG, MIG and PTA processes
- To determine the optimum operating parameters for each process, and measure the increase in productivity
- To determine the approximate operating limits for each process.