Role of Bead Sequence in Underwater Welding

Area of Science:

• Materials Science
• Welding Engineering

Background:

• Underwater welding presents challenges to welding arc stability and weld properties.
• The heat-affected zone (HAZ) in wet welding can exhibit increased hardness, potentially affecting mechanical integrity.

Purpose of the Study:

• To investigate the impact of bead sequence on the properties of underwater wet welds.
• To evaluate the potential of optimizing bead sequencing to mitigate hardness in the HAZ.

Main Methods:

• Two specimens of normalized S355G10+N steel were wet welded using a controlled bead sequence.
• Metallographic macro- and microscopic analyses were performed.
• Vickers HV10 hardness measurements were conducted on pad welds within the welded layers.

Main Results:

• Welding in an underwater environment affects welding arc stability and weld properties.
• Refining and tempering effects were observed in the HAZ of previously laid beads, leading to reduced hardness.
• A reasonable bead sequence decreased HAZ hardness by up to 40 HV10.

Conclusions:

• A strategic bead sequence is crucial for improving underwater wet welding outcomes.
• Heat input from subsequent beads can temper martensite in the HAZ, refining microstructure and reducing cold cracking susceptibility.
• The study demonstrates the feasibility of optimizing bead sequence to enhance weld quality in wet welding applications.