Comparative study of eutectic Al-Si alloys manufactured by WAAM and casting

Geir Langelandsvik,Hans J Roven,Odd M Akselsen,Annbjørg Horgar,Trond Furu

doi:10.1007/s00170-020-05735-7

Abstract

Wire and arc additive manufacturing (WAAM) of metallic materials is expected to become part of the new industrial revolution. The possibilities for complex designs and superior mechanical properties can in many cases replace traditional manufacturing processes such as casting. In order to benchmark the properties of aluminium WAAM components, a comparative study was performed with two different casting techniques: permanent casting with steel mould and sand mould casting. Aluminium-silicon alloys with near eutectic composition were used for the comparison. Porosity levels, secondary dendrite arm spacing, grain size distribution, tensile strength and microhardness were considered for the comparison. The WAAM material exhibited superior mechanical properties originating from a finer dendritic and eutectic microstructure compared with the castings. A slight anisotropy in tensile ductility was observed in the WAAM material, probably due to a coarse microstructural zone between individual beads. All investigated materials had low levels of porosity, < 1% by area fraction. The comparative study has shown that WAAM of aluminium-silicon alloys is well suited for high-integrity applications.

Highlights

The potential to create complex metallic components with superior functional and mechanical properties has encouraged extensive research on additive manufacuring (AM) [1, 2]
The microstructure and mechanical properties of aluminium-silicon alloys with near eutectic composition made by wire and arc additive manufacturing have been benchmarked against two different casting methods
The Wire and arc additive manufacturing (WAAM) material is made out of individual beads which exhibit low through thickness variations of the microstructure in thicker sections

Summary

Introduction

The potential to create complex metallic components with superior functional and mechanical properties has encouraged extensive research on additive manufacuring (AM) [1, 2]. AM has already been utilised in manufacturing of boat propellers, aircraft engine brackets, fuel nozzles and water distribution manifolds, among others [3,4,5]. Wire and arc additive manufacturing (WAAM) is one of the most promising AM techniques. Being a successor of layer-wise welding patented by Baker [6], WAAM employs metallic wire and electric arc welding for strategic deposition of material on a substrate. The deposited material is subjected to repeated solidification and remelting, giving good adhesion between layers and a complex thermal history. WAAM shows very high deposition rates compared with other AM processes, i.e., up to 10 kg/h for ferrous alloys and 1 kg/h for aluminium [7]

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