Effects of casting speed on microstructural and tensile properties of Al-Mg-Si alloy fabricated by horizontal and vertical twin-roll casting

For the development of Al-Mg-Si strips with high mechanical performance via twin-roll casting (TRC) technology, it is necessary to understand through comparative analysis of traditional horizontal twin-roll casting (HTRC) and promising vertical twin-roll casting (VTRC) technologies. In this study, two types of Al-Mg-Si alloys (denoted as H-alloy and V alloy) were fabricated by HTRC and VTRC using different casting speeds (0.69 and 20 m/ min, respectively). The microstructural evolution and mechanical properties of the two alloys were comprehensively assessed and compared. To reveal the microstructural characteristics, various techniques including energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD), texture calculation and differential scanning calorimetry (DSC) were utilized. Center segregation occurred in H-alloy and V-alloy in the form of channel segregation and segregation bands, respectively. Moreover, the texture components of H-alloy showed rolling and shear textures, indicating continuous casting with hot-rolling during HTRC; however, those of V-alloy showed a random texture, indicating the absence of hot-rolling during VTRC. Therefore, the amount of plastic deformation in H-alloy was greater than that in V-alloy, which increased the yield strength through dislocation strengthening. Furthermore, solid-solution strengthening and precipitation strengthening primarily helped improve the strength of V-alloy, whereas pre-existing voids caused premature fracture. Our comparative analysis of the microstructural evolution and tensile properties realized by HTRC and VTRC is anticipated to broaden the understanding of twin-roll-cast strips.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Comparative analysis of traditional horizontal twin-roll casting (HTRC) and promising vertical twin-roll casting (VTRC) technologies was conducted to develop Al-Mg-Si strips with high mechanical performance. Two types of Al-Mg-Si alloys (H-alloy and V alloy) were fabricated and their microstructural evolution and mechanical properties were assessed. It was found that center segregation occurred in both alloys but in different forms, and the texture components and plastic deformation were different between the two alloys, leading to variations in their yield strength. Solid-solution strengthening and precipitation strengthening were found to improve the strength of V-alloy, while pre-existing voids caused premature fracture.