Magnesium Alloy Sheet Produced by Twin Roll Casting

Magnesium Sheet; Challenges and Opportunities

“…Such a small grain size is expected to benefit superplasticity at elevated temperatures. Hot-rolled twin-roll cast AZ91 sheet has exhibited an improvement of 60% in yield stress and 17-40% in UTS (Ultimate Tensile Strength) as compared to the sheets produced from the sand-cast (T6 temper) and die-cast (F temper) slabs (Allen et al, 2001). The fine precipitation within grains has definitely contributed to this improvement in mechanical properties.…”

“…This latter part of the rolling process is time consuming with high operating costs and progressively tends towards lower metal yields. Such a technology also requires expensive quality control procedures and substantial investment in equipment (Dow Chemical Company, 1943;Allen et al, 2001;Bach et al, 2006). This means that a standard magnesium sheet production consists of a complex DC casting, a homogenization treatment, and approximately 12-18 hot rolling passes in 2-3 heats.…”

“…The small dendrite arm spacing in a twin-roll cast AZ91 alloy improved the workability at elevated temperatures. The secondary-dendrite arm spacings can be transformed into recrystallized grains of 9-10 µm in diameter by hot rolling (Allen et al, 2001). Such a small grain size is expected to benefit superplasticity at elevated temperatures.…”

Coupled analysis of temperature and flow during twin-roll casting of magnesium alloy strip

“…Park et al (2009) reported that the metal melt was subjected to plastic deformation during rapid solidification, 10 2 -10 3 • C/s, which was 2-3 orders of magnitude higher than that of the conventional ingot casting. Allen et al (2001) suggested that the twin-roll casting AZ31 magnesium alloy exhibited homogeneity of microstructure, refined grain size, reduced segregation and a dense distribution of fine particles within the solid solution. Mino et al (2006) studied the effect of structure-control rolling on the formability of twin-roll casting AZ61 magnesium alloy.…”

Kinetics of recrystallization for twin-roll casting AZ31 magnesium alloy during homogenization

“…The metal melt is subjected to plastic deformation during rapid solidification, 10 2 -10 3 ºC/s, which is 2-3 orders of magnitude higher than that of the conventional ingot casting [1]. Allen et al [2] suggested that the twin-roll casting AZ31 magnesium alloy exhibited homogeneity of microstructure, refined grain size, reduced segregation, and dense distribution of fine particles within the solid solution. Watari et al [3] produced AZ31, AZ61, and AZ91 magnesium alloy sheets of 2.5-4.5 mm in thickness at a speed of 20 m/min by the twin-roll casting process.…”