Study of the Mechanical Properties of Al–Mg ADC6 Aluminum Alloy Produced by Unidirectional Casting Under Various Cooling Rates

To create the high strength and high ductility of Al–Mg-based aluminum alloy (JIS–ADC6), ADC6 samples were produced by the unidirectional continuous casting (HMC). The HMC process was conducted with direct water cooling to melt ADC6, which can make fine microstructures and control crystal orientation. The cast samples were prepared under various cooling rates (CRs): 6.3, 34, and 62 K/s. The microstructure and crystal orientation of the samples were altered with CR. At CRs of 34 K/s and 62 K/s, the α-Al phases and intermetallic compounds, e.g., Mg2Si and Al15(Fe, Mn)3Si2, became finer and more spherical. The secondary dendrite arm spacing for the sample at 62 K/s was 8.7 µm—more than 70% smaller than the ADC6 sample (ingot) made by a gravity casting process. Notably, at a CR of 34 K/s, the crystal orientation was predominantly arranged with the (101) plane. Tensile properties—ultimate tensile strength (σUTS), 0.2% proof stress (σ0.2), and failure strain (εf)—varied with the CR. The tensile strength (σUTS and σ0.2) consistently increased with increasing the CR. The improvement in the tensile strength resulted from the refined microstructures, such as the α-Al phase and intermetallic compounds. Similarly, the failure strain also increased with increasing CR, which was severely affected by the finer and more spherical intermetallic compounds. In this case, the εf value of the sample at 34 K/s was, however, slightly higher than that at 62 K/s, due to more uniformly organized crystal orientation, while their ductility was much higher than that of the gravity cast sample. The tensile properties in detail were further analyzed using their failure characteristics.

This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/10.1007/s40962-025-01723-3

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