Operational Aspects of Underwater Wet Welding with Austenitic Stainless Steel Coated Electrodes

Abstract

Underwater wet welding is an important joining process for the repair of submerged structures. However, in this process, structural steel weldability is impaired by martensite formation and hydrogen embrittlement. Furthermore, underwater wet welding is also characterized by operational difficulties as low weld pool visibility and poor arc stability. An alternative to reduce some metallurgical problems of underwater welding of structural steel could be the use of austenitic filler metals. To provide an initial background for the use of these consumables, the present paper evaluates the operational characteristics of shielded metal arc electrodes of austenitic stainless steel and compares their characteristics with those of low carbon steel electrode in both dry and underwater wet environments. Welding trials were performed in air and wet operation at three different depths, using both current polarities and on three different base metals. Voltage and current signals were analyzed to determined metal transfer mode and process stability indexes were calculated. In all trials, globular metal transfer with variable short-circuit events was observed. Process evolution during electrode melting was studied. It was shown that electrode melting rate of austenitic electrodes was higher than that of the low-carbon electrode. However, this difference was smaller in underwater welding.

Key-words:
Stability; Fusion rate; Wet welding