Prediction of weld defects using welding condition data

The behaviour of different welding process parameters monitored in GMA-welding during artificial disturbances intended to produce weld defects is described. The disturbances include both electric parameter deflections such as deflections in travel speed, wire feed speed or welding voltage, and mechanical factors such as water, oil, grease, shop-primer or rust in the weld groove, as well as disturbed shielding gas flow. The monitored parameters include welding voltage, current and energy, travel speed, wire feed speed, short-circuiting frequency, proportional arc duration and arc sound emission. The experiments were made using short arc and spray arc welding. The effect of the different disturbances on weld quality is described. Also the ways of detecting the disturbances and consequently the actual weld defects with the aid of the monitored parameters are discussed. The technique opens the possibilities of replacing NDT of welds with welding process control.