Multimodal defect analysis and application of virtual machining for solid-state manufactured aluminium structure

Area of Science:

• Materials Science
• Manufacturing Engineering
• Metallurgy

Background:

• Additive friction stir deposition (AFSD) is a solid-state additive manufacturing technique offering wrought-like properties.
• The effects of process interruptions on defect formation in AFSD parts are not well understood.

Purpose of the Study:

• To investigate defect formation and mechanical properties of Al6061 alloy manufactured by AFSD with process interruption.
• To understand microstructure development and material flow during interrupted AFSD.

Main Methods:

• Manufacturing of Al6061 structures using AFSD with deposition interruption.
• Characterization using optical microscopy, electron microscopy, X-ray computed tomography, electron backscatter diffraction, and Vickers hardness testing.
• Virtual machining for defect analysis and post-processing simulation.

Main Results:

• Achieved >99% relative density with minimal defects in the center, but tunnel defects and kissing bonds were observed at interfaces and edges.
• Identified localized shear bands with fine grains (1-5 µm) and kissing bonds linked to grain size differences.
• Vickers hardness varied with deposit height, and virtual machining indicated defect removability.

Conclusions:

• AFSD of Al6061 with interruption produces dense parts but requires attention to interface and edge defects.
• Microstructure analysis reveals localized shear and grain size effects on bonding.
• Post-processing strategies can enhance the mechanical integrity of AFSD components.