The increasing processing of high-strength alloys and composite materials in automotive, power, mechanical and plant engineering needs production tools with, e.g., high strength, hardness and wear resistance. Compared to the acquisition of new tools, repair welding processes are more efficient and resource-saving due to longer tool life time [1,2]. For high-alloyed, complex tools applied for injection molding or precise cutting with high sensitivity to thermal distortion, laser deposition welding is the favored welding process due to its high-density, but lower heat input per unit length compared to arc welding [1]. This reduces the heat-affected zone and, thus, residual stress and cracking in the weld metal. Compared to arc welding processes, laser welding is further advantageous due to more precise positioning and focusing of the beam, more process flexibility as well as application in narrow areas [1].

For manual laser deposition welding, commonly solid wires with diameters in the sub-mm range are used to build up or repair filigree structures or larger areas. The manufacturing of such thin wires is quite challenging, even more, when high-alloyed steels with a high amount of carbon and carbide-forming elements are applied. However, those high-alloyed steels are very attractive for tool repair to maintain the hardness and wear resistance of the substrate material in the welding seam. For metal forming, several intermediate heat treatments, and a high forming power would be necessary. To avoid this complicated and costly processing route, we applied the powder-in-tube method for which we developed a filler wire with the nominal composition given by the desired tool steel in total, but separated the constituents into a well-formable shell material with poorly formable constituents placed inside. Such wires are well-known for arc welding, but for manual laser deposition welding, however, have not been applied yet.

The powder-in-tube-composite was cold worked with the help of a 4-plunger rotary swager from 20 mm to an outer diameter of about 1 mm. Those wires were processed by manual laser deposition welding to receive multilayer welding seams with high quality and hardness values of 700 HV0.1 and more.

Funding of this project by AiF under project number KK5259201SU1 is gratefully acknowledged.

References
[1] M. Vedani, J. Mater. Sci., 2004, 39, 241-249. https://doi.org/10.1023/B:JMSC.0000007750.16970.4e
[2] J. Kimme, J. Zeisig, A. Fröhlich, V. Kräusel, Metals, 2021, 11, 1820. https://doi.org/10.3390/met11111820