Enhancement of Microstructure, Tensile and Fatigue Performance of EN AW-1050 by Wire-Based Friction Stir Additive Manufacturing

Additive manufacturing (AM) of aluminium by solid-state routes offers a promising pathway to overcome the limitations of fusion-based processes, such as porosity and hot cracking. This study investigates the potential of wire-based friction stir additive manufacturing (W-FSAM) as an innovative solid-state process. A test specimen made of EN AW-1050 was fabricated and characterised using mechanical testing as well as optical and electron microscopy. Microstructural characterisation revealed a fully consolidated, pore-free build with fine equiaxed grains and partial dynamic recrystallisation (DRX). The average grain size decreased from 13.4 µm near the substrate to 9.7 µm at the top, reflecting the variation in cumulative thermal exposure along the build height. A homogeneous hardness distribution (21.2 HV) and smooth interlayer interfaces were observed. Tensile tests in the travel direction yielded an ultimate tensile strength of approximately 85 MPa and an elongation exceeding 60%, while high-cycle fatigue tests demonstrated a fatigue strength of about 30 MPa at 2×106 cycles (R=0.1) with ductile fracture features. The results confirm that W-FSAM enables the production of fine-grained, defect-free CP-Al structures whose mechanical properties, in terms of strength and ductility, exceed those of the reference material. Thus, W-FSAM represents a promising solid-state additive manufacturing route for the production of high-performance CP-Al components.