Electric discharge assisted post-processing performance of high strength-to-weight ratio alloys fabricated using metal additive manufacturing

Abstract

Metal additive manufacturing (MAM) is a near net shape fabrication process intended for producing complex and intricate shaped metallic parts/components. The feasibility in batch production as well as minimal material wastage establish the potential of MAM over other manufacturing methods. MAM of high strength-to-weight ratio alloys such as AlSi10Mg and Ti6Al4V is gaining popularity nowadays owing to their never ending demand in aerospace, automotive and biomedical industries. Both the alloys mark the two extreme ends of commercially available MAM alloys in terms of contrasting material properties. However, the poor surface integrity achieved by AlSi10Mg and Ti6Al4V parts/components after MAM demands post-processing via laser energy, chemicals, abrasives, conventional cutting tools etc. A recently developed low energy wire electrical discharge polishing (WEDP) method showed promising outcomes in MAM post-processing over aforementioned methods. In the present study, the performance and feasibility of WEDP in post-processing AlSi10Mg and Ti6Al4V are investigated with reference to the contrary properties associated with the alloys. The significant difference in melting point, thermal conductivity and chemical affinity led to distinct outcomes for the two alloys after WEDP. The enhancement in surface finish (Sa) was ~79% and ~91% for AlSi10Mg and Ti6Al4V respectively. The excellent corrosion resistance offered by the alloys is found to be unaltered in case of AlSi10Mg whereas enhanced for Ti6Al4V after WEDP. Modification in subsurface microhardness was observed upto 300 µm depth from polished surface for AlSi10Mg, whereas absent in Ti6Al4V. The study also revealed that the WEDP induced bigger craters in AlSi10Mg as well as cracks and resolidified layer in Ti6Al4V can be minimized at lower settings of pulse on time (T ON ). Moreover, EDS and XRD analysis indicated the formation of an oxide layer over Ti6Al4V surface after WEDP. • Wire electrical discharge polishing of high strength-to-weight ratio alloys having contrasting physical properties. • An in-depth surface integrity and corrosion behaviour analysis. • Polished surface analysis through detailed characterization methods. • Improvement in surface finish by ~79% and ~91% fData availabilityor AlSi10Mg and Ti6Al4V, compared to the as-built samples.