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

Abstract

Mn-containing (2 and 4 mass%) Al–Mn-based alloys were fabricated by high-speed twin-roll casting (HSTRC). Al–4 mass%Mn–1 mass%Si strips contained coarse particles in the central band of the cast strips. Microstructure and chemical analyses revealed that the particles were primarily Al₆(MnFe) and β-Al(MnFe)Si. These particles formed during the solidification process of the residual liquid, which slowly cooled after the strip exited the roll gap during HSTRC. However, blowing compressed air onto the strip surface as it exited the roll gap rapidly cooled the residual liquid, reducing the number and size of large particles in the central band region. The cold-rolled and annealed sheets fabricated from the strips exhibited a refined and homogenous microstructure. Consequently, both the strength and elongation of the sheets were improved.