The Effect of the β-Al5FeSi Phases on Microstructure, Mechanical and Fatigue Properties in A356.0 Cast Alloys with Higher Fe Content without Additional Alloying of Mn.

Lenka Kuchariková,Michaela Kritikos,Denisa Medvecká,Eva Tillová,Juraj Belan,Mária Chalupová,Milan Uhríčik

doi:10.3390/ma14081943

Lenka Kuchariková, Michaela Kritikos + Show 5 more

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https://doi.org/10.3390/ma14081943

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Abstract

Secondary-cast aluminum alloys have increasing industrial applications. Their biggest deficiency is their impurity content, especially Fe, which has low solubility in Al and almost all the content creates intermetallic phases. This work examines the effect of higher Fe content on the microstructure and properties of A356.0 alloy. At the same time, no other possibility existed to affecting the brittleness of the formation of the β phases. The calculation of Fecrit, ratio of Mn/Fe, quantitative and computed tomography analysis of porosity and Fe plate-like phases, measurement of mechanical and fatigue properties, and fractography analysis were performed in this study. The results show that gravity die casting into a sand mold, and the non-usage of Mn addition or heat treatment, do not have a negative effect on increasing the size of the Fe-rich plate-like phases. The longest Fe-rich phases have limited the pore growth and ratios, but their higher thickness led to greater porosity formation. The mechanical and fatigue properties correlate with the Fecrit level and the highest were for the experimental alloy with 0.454 wt.% of Fe. The experimental results confirmed the fact that if the Fe plate-like phases have a length of up to 50 µm, the fatigue properties depend more on the size of porosity. If the length of the Fe needles is more than 50 µm, then the properties are mainly affected by the length of these Fe phases.

Highlights

This study presents an analysis of the microstructure and property changes of
The benefits of this study are results for materials without Mn alloying and heat treatment, which are commonly used in production of aluminum cast products
The results of this study demonstrate the great effect

Summary

Introduction

The general need for weight-saving to reduce fuel consumption leads increasing interest in aluminum alloys for automotive applications. It should be noted that the production of a ton of primary aluminum requires an order of magnitude higher energy consumption compared to the production of a ton of iron-based alloy. It is very urgent to comprehensively increase the use of the secondary aluminum alloys (made from scrap metal processing), the production of which allows a reduction of energy consumption by up to twenty times (secondary only requires about 2.8 kWh/kg to produce, while primary requires about 45 kWh/kg), compared to primary production, with a significantly lower environmental load [1,2,3]. The recycling of aluminum scrap can save energy, but other raw materials, as well [4]

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