Effect of tool design and pass strategy on defect elimination and uniform, enhanced tensile properties of friction stir processed high-pressure die-cast A380 alloy

Abstract

This work reports a study of friction stir processing (FSP) using different tool designs and altering the pass strategy for two process parameter combinations to locally modify the microstructure and create a defect-free processing zone. FSP is applied on high-pressure die-cast (HPDC) A380 alloy, which is widely used in the die-casting sector for automotive and aerospace applications. Gas and shrinkage porosity, brittle, needle-shaped Fe-containing β-FeSiAl5 intermetallic compounds, Al dendrites, coarse and acicular silicon particles, and large second-phase particulates diminish the uniformity of tensile properties across the thickness of an HPDC plate. FSP can eliminate porosity, refine microstructure, and improve tensile properties. An FSP tool design and a pass strategy are identified for the best microstructure consolidation and uniform, enhanced tensile properties. This study underscores the importance of tool features such as scroll design and flats on tool pins and multiple pass-orientation strategies to optimize defect-free, refined microstructure and uniform tensile strength and ductility across the processing zones of HPDC Al alloys.