Influence of the Cross-sectional Area of Consumable Nozzle on Welding Phenomena in Electroslag Welding

Abstract

Influence of the cross-sectional area of consumable nozzle on the penetration in base plate and its stability and the possibility on the control of welding phenomena by changing the nozzle current is investigated using the mild steel plate with the thickness of 30 mm to develop narrow gap electroslag welding process with high efficiency and low heat input.
It is experimentaly shown that the nozzle with large crosssectional area is useful in stable and high current welding process because of dispersing the welding current in slag pool by increasing the nozzle current. So, the method for estimating the nozzle current during welding is designed and, by this method, the nozzle current is estimated under various conditions in connection with the cross-sectional area of the nozzle.
Adopting above results to high current narrow gap welding process, it is clarified that more stable and uniform penetration can be obtained by using the nozzle with large cross-sectional area. This result is due to the preheating effect at root faces of base plate in slag pool and dispersing the heat source in slag pool by increase of nozzle current.