Solidification Structure and Secondary Particles in Vertical-Type High-Speed Twin-Roll Cast 3003 Aluminum Alloy Strip

Abstract

The effect of cooling rate on microstructure of vertical-type high-speed twin-roll cast 3003 aluminum alloy strip was investigated. The solidification structure was characterized in terms of grain size and kinds, size, morphology and chemical composition of secondary particles. The 3003 aluminum alloy strip consisted of cell structure, dendritic structure, globular grains and eutectic structure along the strip thickness direction. From the relationship between the cooling rates and as-cast grain size, the cooling rate of high-speed twin-roll cast strip surface area was estimated as 3.1 © 10 3 K/s. Significant differences in the formation of secondary particles were found between direct chill (DC)-casting and the high-speed twin-roll casting as a result of the different cooling rates; Al 6 (Mn,Fe) and ¡-Al(Mn,Fe)Si phase were identified in the DC-cast sample, whereas only ¡-Al(Mn,Fe)Si was predominant in the high-speed twin-roll cast strip. The Al 6 (Mn,Fe) particles in DC-cast sample were script-like morphology with high aspect-ratio. In contrast, ¡-Al(Mn,Fe)Si particles in the high-speed twin-roll cast strip was spore-like morphology. Most ¡-Al(Mn,Fe)Si particles in the strip were considered to be formed as one of the eutectic components from the liquid droplets trapped in the inter-dendrite regions. In particular, Fe-rich ¡-Al(Mn,Fe)Si phase was formed at strip central area due to the increase in Fe segregation at the growth front. [

Microstructure and mechanical properties of high-manganese-containing high-speed twin-roll cast Al-Mn-Si alloy strips and their cold-rolled sheets

“…5 shows a representative microstructure of A1, and A3 at the near-surface, a quarter of the thickness and the central regions. The microstructure was the typical dendritic structure, which was similar to that of the HSTRC 3003 strip [8]. At the near-surface region, cellular and equiaxed dendrite crystals were observed.…”

Effect of Large Particles in Central Band of Al–4%Mn–1%Si High-Speed Twin-Roll Cast Strip on Elongation of Cold-Rolled and Annealed Sheets

“…28) The high cooling rate of HSTRC favors the formation of the ¡-Al(Mn, Fe)Si phase instead of the Al 6 (Mn, Fe) phase, which is frequently observed in the DC cast 3003 aluminum alloy. 21) Although the near-surface region of 4M1S shows Al, Si, and ¡-Al(Mn, Fe)Si peaks, the mid-thickness region exhibits peaks for the ¡-Al(Mn, Fe)Si and Al 6 (Mn, Fe) phases. Figure 5(f ) indicates that there are many blocky/ platelet and needle-like particles in the mid-thickness region of 4M1S.…”

“…The strip's productivity is also improved by utilizing a high cooling rate (over 10 3 C/s) and a high casting speed (60120 m/min). 2123) The enhanced cooling rate leads to various benefits in the metallurgical characteristics in terms of enhancing super-saturation of alloying elements, grain refinement, and fine distribution of secondary particles 21,2325) Employing HSTRC is an option to fabricate a high Mn mass% of Mn-containing alloys. A report found that the mechanical properties of the sheets fabricated from the cast strips are superior to those of commercial alloys.…”

The Effects of Microstructure Refinement and Coincidence Site Lattice Boundaries on the Plasticity of FeCrAlY Alloys

“…TRSC underwent subrapid solidification with a cooling rate in the range of 10 2 -10 3 °C s À1 during solidification, which was three to five orders of magnitude higher than conventional IC. [26,27] 2) The steel liquid flowed back and dashed against solid-liquid interface dramatically. 3) Deformation occurred during the solidification process.…”

“…Finer secondary phase and more low-Σ CSL boundaries were obtained through twin-roll strip casting (TRSC), which was characterized by subrapid solidification. [26,27] CSL maps and morphologies of the secondary phase were carried out to investigate the influence of microstructural refinement and CSL boundaries on elongation behaviors. The formation mechanism of low-Σ CSL boundaries and the enhanced ductility of the FeCrAl alloys were discussed.…”