Fundamental Study on Weld Formation Phenomena of High speed Lap Seam Welding (1st Report)

Effects of Main Welding Conditions on Weld Formation

Abstract

The influences of wedling current, welding speed and electrode force on the size and shape of the nugget and HAZ, indentation and weld formation process are studied using cold rolled mild steel having thickness of 1.2 mm. The results obtained are as follows.
Nugget width, penetration and indentation increase with the increase of welding current and the upper limit of welding current is restricted by the occurance of surface flash. As welding speed increases the rate of increase of penetration as against the increase of current becomes larger which restricts the upper limit of welding speed. Increased electrode force enlarges the weldable welding current range, especially under high speed condition. According to the observation of longitudinal sections, weld formation process can be divided into two types with welding speed. In case of an electrode force of 480 kg, the transition welding speed is about 4 m/min which coincides with the welding speed at which melting efficiency is saturated.