Welding of Additively Manufactured Materials: Preliminary Assessment
By A Addison and A Allison
Parts manufactured by additive manufacturing (AM) processes often have microstructures that are different from ‘conventional’ materials, such as cast or wrought products. It may be necessary to join such parts to other AM parts or to cast or wrought materials using conventional arc welding processes. In such circumstances, the effect of the microstructure of the AM part on the weld is of interest.
This report describes work carried out to prepare a limited number of illustrative examples to assist decisions about future development work in this area. The parts to be welded were fabricated by laser powder bed fusion (PBF) or directed energy deposition-arc (DED-Arc), sometimes referred to as wire plus arc additive manufacture (WAAM)
- Welding of most AM materials by conventional means is both possible and relatively insensitive to the configuration of the AM material relative to the weld interface.
- At the macro scale, the structures in the HAZ and weld metal of the joints were entirely conventional in their nature and no unusual or unexpected microstructure was seen to form as a result of the incorporation of AM material into the joint.
- It was noted that significant porosity occurred adjacent to the fusion boundaries of the joints between aluminium PBF specimens. It is felt that the most likely cause of this is dissolved gas being released from the PBF microstructure and boiling out through the weld metal.
Stainless steel PBF weld macro cross-section.
Ti-6Al-4V PBF weld macro cross-section.