Efficient process for welding under water

Togeth­er with an indus­tri­al part­ner, the Laser Zen­trum Han­nover e. V. (LZH) has devel­oped a laser-based met­al flux-cored weld­ing process for use under water. The process is intend­ed to facil­i­tate weld­ing work under water and pro­duce bet­ter weld seams.

Whether for wind farms, coastal pro­tec­tion struc­tures or har­bors, when tech­ni­cal con­struc­tions have to be weld­ed under­wa­ter, divers usu­al­ly use man­u­al elec­trode weld­ing. Sci­en­tists at the LZH are now devel­op­ing an alter­na­tive process togeth­er with AMT GmbH from Aachen. Laser-assist­ed met­al flux-cored weld­ing under water is intend­ed to facil­i­tate weld­ing under water and pro­duce bet­ter weld seams.

Goal: Optimize flux-cored welding with the laser

Man­u­al elec­trode weld­ing, which is rel­a­tive­ly sim­ple and inex­pen­sive, has become estab­lished for under­wa­ter weld­ing work. How­ev­er, it has the major dis­ad­van­tage that the divers:inside have to replace the burned-off elec­trodes fre­quent­ly. This means that the process has to be inter­rupt­ed time and again, espe­cial­ly for longer welds.

In flux-cored weld­ing, on the oth­er hand, wire can be con­tin­u­ous­ly fed from a wire reel, which is then melt­ed. This makes it pos­si­ble to pro­duce sig­nif­i­cant­ly longer weld seams, thus increas­ing depo­si­tion rates and pro­duc­tion rates. The sci­en­tists at the LZH now want to opti­mize flux-cored weld­ing with the aid of laser radi­a­tion. The goal is to devel­op laser-assist­ed met­al flux-cored weld­ing as a qual­i­ta­tive­ly con­vinc­ing and more effi­cient alter­na­tive for weld­ing under water.

Laser radiation to improve arc ignition and process stability

The laser beam will intro­duce tar­get­ed ener­gy into the work­piece to improve arc igni­tion and sta­bil­i­ty. Stud­ies of laser beam-arc hybrid weld­ing on atmos­phere have shown that the tar­get­ed com­bi­na­tion of laser beam and arc in a com­mon process zone allows the arc to be pre­cise­ly guid­ed, result­ing in high­er process sta­bil­i­ty and geo­met­ric accu­ra­cy of the weld prox­im­i­ty. In addi­tion, high­er weld­ing speeds and the over-weld­ing of exist­ing weld seams are pos­si­ble. In the LaMeer project, the part­ners now want to inves­ti­gate the com­bi­na­tion of laser beam and arc in under­wa­ter appli­ca­tions. To this end, they want to devel­op and test a weld­ing torch pro­to­type with inte­grat­ed laser optics.

Growing importance of underwater welding

The mar­itime indus­try is one of the most impor­tant eco­nom­ic sec­tors in Ger­many. Weld­ing, as one of the key tech­nolo­gies in under­wa­ter engi­neer­ing, is becom­ing increas­ing­ly impor­tant, espe­cial­ly against the back­drop of cli­mate change, for exam­ple in the fields of ener­gy gen­er­a­tion and coastal pro­tec­tion. The LaMeer project (laser-assist­ed met­al filler wire weld­ing under­wa­ter) is fund­ed by the Ger­man Fed­er­al Min­istry of Eco­nom­ics and Cli­mate Pro­tec­tion under the fund­ing code KK5111705SU1 by the project spon­sor AIF Pro­jekt GmbH.