Investigation of Bubbles Phenomenon in Underwater Wet Welding with Self-Protected Tubular Wire

Abstract

The bubble formation mechanism is strongly associated with variation in electrical signals and arc stability in underwater wet flux cored arc welding (FCAW). Good understanding of bubble formation mechanism can be helpful in achieving welding parameters that produce better weld beads. This work aims to investigate the dynamic behavior of bubbles formed in underwater wet welding, searching for a relation between frequency of formation and size of formed bubbles associated with changes in welding parameters. Verify the bubble evolution modes related to electrical signals and compare bubble formation in two different conditions, welding with the contact tip immerged in water and with the contact tip dry inside a welding torch that isolates it from the water environment were achieved. The bubble formation mechanism was an unstable phenomenon and bubble geometry is constantly changing. Thus, it was possible to conclude that controlling the welding parameters is possible to optimize bubble diameter and, so, improve arc protection avoiding its extinction.

Key-words:
Underwater welding; ARC stability; Bubble evolution mechanism