Investigation of the hydrogen content in the process zone and the resulting hydrogen deposition in the weld metal during underwater wet arc and laser beam welding (WaPro)

• Applicants: Dr.-Ing. Thomas Hassel; Professor Dr.-Ing. Volker Wesling
• Subject Area: Joining and Separation Technology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461883637

The hydrogen input into the material poses a considerable challenge when welding under water. However, there are no fundamental studies on the dependence of the hydrogen content in the process zone and the resulting hydrogen input into the weld metal for wet arc and laser beam welding. Therefore, urgent questions arise from the state of the art in research, which have to be answered within the scope of the project applied for:1. can the place of origin of the hydrogen in the process zone be determined? What is the role of the transition zones arc/laser beam workpiece, arc/laser beam bubble and gas bubble water? 2 How do the process parameters influence the hydrogen production in the process zone? 3. does a changed hydrogen concentration in the process zone lead to a changed hydrogen input into the weld metal?4. how do the hydrogen generation and the hydrogen input depend on the welding energy form (compare arc - laser radiation)?5. can spectrometric data from underwater processes be used to determine the quantity of hydrogen produced in the process zone?The overall objective of the project is to investigate the hydrogen content in the process zone and the resulting hydrogen input into the weld metal during wet arc and laser beam welding under water. An essential aspect here is to understand at which point of the process zone the hydrogen is formed and how the main process parameters affect the formation and quantity. Another aim is to clarify how the hydrogen concentration in the process zone affects the hydrogen input into the weld seam. Finally, the knowledge to be aimed at is to be combined in order to derive possibilities of hydrogen reduction in wet arc and laser beam welding. As an example, a final comparison of hydrogen hazards for both welding processes shall be carried out for selected weld seam geometries of practical relevance, such as a fillet weld.

• DFG Programme: Research Grants