Quantitative analysis of 3D pore characteristics effect on the ductility of HPDC Al–10Si-0.3 Mg alloy through X-ray tomography

Abstract

Due to the uncertain fracture of the die-casting aluminum component (shock tower), X-ray tomography (XRT) coupled with digital image correlation (DIC) was implemented to understand various pore characteristics, specifically spatial distribution and morphology of porosity, and their influences on the ductility in thin-walled Al–10Si-0.3 Mg high pressure die casting. XRT analysis reveals that there was a great amount of porosity in the samples, which was heterogeneously distributed. DIC measurement indicates that porosity gave rise to strain concentration and reduced ductility. Finite element simulations were performed to reveal the combined effect of the pore size and location. Though the morphology and location of pore had nonnegligible impacts on ductility, the local porosity in fracture region played a dominant role in determining it. The local porosity in fracture region can't be obtained prior to tensile testing and consequently ductility can't be predicted based on it. It was found that, for the 27 studied samples, the local porosities in fracture regions were equal or close to the highest local porosities in the gauges, and the samples with higher level of the highest local porosity generally showed lower elongations. The range in which the ductility falls could be estimated according to the highest local porosity in the gauge, which can be achieved before tensile testing. The factors accounting for the difference between upper and lower bounds on ductility were also discussed.

Keywords

• Aluminum alloy
• High pressure die casting
• Porosity
• Ductility
• X-ray tomography
• Strain heterogeneity