Researches on the Macro- and Micro-Structures and Properties of the Vertical Bending Continuous Casted AA6063 Thin Slabs and Their As-Rolled Sheets

Abstract

A 6063 aluminum alloy thin slab with a cross-section of 260 × 40 mm2 was prepared by a vertical bending continuous casting (VC) process. The effects of homogenization, hot rolling and subsequent heat treatments on the microstructure and properties of the as-cast slabs and as-rolled sheets were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), field emission electron probe (EPMA), macro- and micro-structure observation and tensile tests. The results show that the as-cast structure of AA 6063 was dominated by fine and uniform equiaxed grains. After homogenization, all Mg2Si phases dissolved back, and the Fe-containing intermetallic phases changed from acicular β-Al5FeSi phase to spherical α-Al8Fe2Si phase. Homogenizing heat treatment before hot rolling can improve the mechanical properties of the alloy. However, in the case of direct rolling without homogenization, the alloy still has good mechanical properties; the strength and plasticity are comparable to that obtained through traditional direct chill (DC) casting, homogenizing and extruding processes, indicating that the VC process has the potential to realize continuous casting and rolling.