UK-based R&D experts, TWI Ltd provide joining knowhow for additively manufactured (AM) metallic components, with a focus on vacuum brazing and diffusion bonding of laser powder bed fusion (L-PBF) materials such as 316L austenitic stainless steel and aluminium alloys AlSi10Mg and Scalmalloy.
The capability on offer supports larger AM assemblies, multi-material structures and structures with complex internal geometries. Covering AM-to-AM and AM-to-wrought joining process development for metallic parts created using laser powder bed fusion (L-PBF) among other techniques, TWI addresses size, materials and geometry limitations for L-PBF AM by splitting component into printable sub-parts and joining them post manufacture. The main functions include the assembly, modification/process improvement and production of complex shaped, high-value metallic hardware.
Available expertise includes joint design for AM, surface preparation, thermal cycle selection and joining by vacuum brazing and/or diffusion bonding (uniaxial or hot isostatic pressing). The AM expertise is further supported by destructive and non-destructive evaluation, metallography, microstructural assessment and functional testing.
Applications and Advantages
AM-to-AM joining allows for larger or more complex final parts to be built than would be possible in a single AM envelope. In addition, it opens up multi-material and graded assemblies where a single material build part would not meet requirements. Vacuum brazing and diffusion bonding, as joining processes for AM, reduce localised parent material melting, residual stresses, heat affected zone (HAZ) and relatively high levels of distortion in comparison to fusion welding processes. These joining processes are also better suited to joining parts with thin walls, lattices and internal channels.
This technology solution could be applied to heat exchangers, manifolds, propulsion and fluidic parts, structural brackets, complex assemblies with enclosed passages, and multi-material transition components.
TWI’s approach integrates joint design, filler/interlayer selection, thermal cycle development and qualification testing to provide an evidence-based joining route for each application.
You can find out more about this technology offering, here: