High frequency resistance welding(HFRW) is used for longitudinal seam welding of pipes. This process provides an efficient means of pipe manufacturing by using high frequency current that tends to flow only near the surface of the pipe. Penetrator, a kind of weld defect, is a slag inclusion accompanied by medium and high power input conditions.
This research is aimed at understanding the mechanism of flash and penetrator formation. For this purpose, the simulations of flash and penetrator formation using VOF(Volume of Fluid) method and the HFRW experiments by ERW simulator are performed. This research proposes the electromagnetic force model considering the skin effect to predict the dynamic behavior of the molten metal on the edge of the pipe. Using the proposed model, the distribution of electromagnetic force is calculated. Also the effects that the operating variables have on the flash formation are investigated quantitatively and the shapes of the narrow-gap zones are calculated with various welding conditions. The types of welding phenomena are determined by the calculated narrow-gap shapes and are compared with the results of experiments performed by Haga to show reasonably good agreements.
