Underwater Wet Welding Techniques and Mechanical Properties

Underwater wet welding remains the predominant method for in situ repair and fabrication of marine structures, pipelines and offshore platforms. Conducted directly in the aquatic environment without a dry habitat, it typically employs shielded metal arc or flux-cored arc processes. The technique is challenged by rapid quenching, arc instability and hydrogen ingress, which elevate the risk of cold cracking and modify microstructural evolution. Innovations such as temper bead welding (TBW), ultrasonic-assisted arc control and local cavity approaches aim to temper the heat-affected zone, refine martensitic constituents and reduce residual stresses. More advanced schemes, including laser welding and direct metal deposition under water, offer improved focal energy density and minimised dilution, while presenting distinct metallurgical kinetics compared with in-air operations. Mechanical properties of wet welds are governed by weld metal composition, cooling rate and post-weld thermal cycles. Key performance metrics include tensile strength, ductility, hardness distribution and susceptibility to hydrogen-induced cracking. Corrosion behaviour, often influenced by galvanic interactions between weld metal and substrate, is a critical long-term consideration. Collectively, these developments underpin the integrity and service life of submerged structures, with immediate relevance to offshore wind foundations, subsea pipelines and coastal defence assets.

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Underwater Wet Welding Techniques and Mechanical Properties publication trend

The graph below shows the total number of articles in underwater wet welding techniques and mechanical properties across all publications each year (not limited to Nature Index journals).

Technical terms

Underwater wet welding: A welding process performed directly in water, using consumable electrodes that are exposed to the aquatic environment.

Heat-affected zone (HAZ): The region of base material adjacent to the weld metal where microstructure and mechanical properties have been altered by heat.

Diffusible hydrogen: The fraction of hydrogen in the weld metal that is mobile at room temperature and can promote cold cracking.

Temper bead welding (TBW): A welding technique in which subsequent beads temper the previously deposited layer, reducing hardness peaks and cracking susceptibility.

Austenitic consumables: Welding electrodes or wires composed of austenitic stainless steel or nickel-based alloys that reduce hydrogen solubility in the weld metal.

References

1. Corrosion behavior of austenitic stainless steel and nickel-based welded joints in underwater wet welding. npj Materials Degradation (2024).
2. Advantages of the Application of the Temper Bead Welding Technique During Wet Welding. Materials (2019).
3. Underwater wet welding of S1300 ultra-high strength steel. Marine Structures (2022).
4. Dynamic control of current and voltage waveforms and droplet transfer for ultrasonic-wave-assisted underwater wet welding. Materials & Design (2019).
5. Underwater Local Cavity Welding of S460N Steel. Materials (2020).
6. Underwater Laser Welding/Cladding for High-performance Repair of Marine Metal Materials: A Review. Chinese Journal of Mechanical Engineering (2022).