Induction Heating in Underwater Wet Welding-Thermal Input, Microstructure and Diffusible Hydrogen Content.

Area of Science:

• Materials Science
• Welding Engineering
• Metallurgy

Background:

• Hydrogen-assisted cracking is a critical issue in underwater wet welding of high-strength steels.
• Traditional post-weld heat treatments are not feasible in wet welding environments.
• Induction heating offers a potential solution by generating heat directly within the workpiece.

Purpose of the Study:

• To characterize thermal input from an underwater induction heating system.
• To evaluate the impact of post-weld induction heating on weldment microstructure.
• To quantify the reduction in diffusible hydrogen content in weld metal.

Main Methods:

• Characterization of thermal input using a commercial induction heating system under water.
• Microstructural analysis of weldments in structural steels with varying strength and composition.
• Quantification of diffusible hydrogen using the carrier gas hot extraction method.

Main Results:

• The thermal input of the underwater induction heating system was successfully characterized.
• Post-weld induction heating was shown to influence the microstructure of the weldments.
• A significant reduction of -34% in diffusible hydrogen content was achieved at a simulated water depth of 30 m.

Conclusions:

• Post-weld induction heating is a viable method for reducing diffusible hydrogen in underwater wet welds.
• This technique can help mitigate hydrogen-assisted cracking in high-strength steel welds.
• Induction heating presents a promising approach for improving the integrity of underwater welded structures.