Effect of electromagnetic fields on microstructure and mechanical properties of sub-rapid solidification-processed Al-Mg-Si alloy during twin-roll casting

The main purpose of this study was to investigate the effects of different external physical fields on the microstructure and mechanical properties of sub-rapid solidification-processed Al-Mg-Si alloy. The microstructural evolution, compositional distribution, hardness, and mechanical properties of cast-rolled strips with and without the application of external fields were studied in detail using metallographic microscopy (OM), electron probe microanalysis (EPMA), tensile tests, and hardness tests. When an external field was applied, the structure of alpha-Al became equiaxed and fine, the area fraction of non-equilibrium eutectic phases greatly decreased; the improvement effect was greatest under application of an electromagnetic oscillation field. By virtue of the electromagnetic braking effect and shock wave effect resulting from application of a static magnetic field and pulsed current field, respectively, the uniformity of the microstructure and composition distribution was improved and the mixing capacity and solid solubility of the alloy elements in matrix were increased. These changes reduced the difference in the hardness in the thickness direction and in the mechanical properties in the width direction, ultimately improving the overall mechanical properties of the AA6022 Al-Mg-Si alloy cast-rolled strips.