Effect of parametric modifications and post-processing on surface properties for Ti-6Al-4V manufactured using electron beam powder bed fusion

Electron beam powder bed fusion (PBF-EB/M) components typically exhibit high as-built surface roughness, partly due to powder sintering during the pre-heating stage. Post-processing techniques by chemical immersion in acids has been shown to reduce the surface roughness. A three-stage experimental approach was employed to investigate the post-processing chemical immersion technique for PBF-EB/M produced Ti-6Al-4 V ELI components. The experimental approach determined that using 1% hydrofluoric acid at room temperature with an immersion time of 120 min resulted in a reduction of various roughness parameters (Ra, Rq, Rz, Rp and Rv) by around 20% each. Additionally, two different EB scan strategies, continuous contouring and multi-spot contouring, were also investigated. The choice of scan strategy did not significantly affect the previously mentioned roughness parameters, however, continuous contouring did increase the Rsm significantly by 45%, and produced distinct changes in the surface morphology. The findings establish a reference for how chemical immersion and scan strategy selection affect surface characteristics, supporting future planned mechanical testing to evaluate their impact on the functional behaviour of PBF-EB/M Ti-6Al-4 V ELI components.