The Influence of Alloy Composition on Phase Transformations and Recrystallization in Twin-Roll Cast Al-Mn-Fe Alloys

Abstract

Twin-roll casting (TRC) is an advantageous substitution for Direct-Chill (DC) casting in the manufacturing of rolled aluminium products. The results of a study of the phase transformations and their interaction with recrystallization occurring during the annealing of TRC Al-Mn based alloys are reported. Four alloys with different contents of Mn, Si and Fe were investigated. Precipitation was studied by resistometric measurements in the course of a heating at linear rate. The microstructural processes responsible for the observed changes in resistivity were identified by TEM examinations of quenched specimens. The changes in the microstructure and solute content during homogenisations at 450°C and 610°C were monitored by conductivity and hardness measurements and polarised light microscopy. It was elucidated that the temperature and kinetics of phase transformations are influenced not only by the content of Mn, but also by Si content. In alloys with low Si content, the decomposition of solid solution and the transformation of primary phases occur in much larger temperature range than in the alloys with high Si content. The precipitation of Mn and Si, concurrent to recrystallization, was observed to retard the latter, especially in alloys with high Mn and Si content.

The influence of dispersoids on the recrystallization of aluminium alloys

“…In accordance with recent investigations [4] our microstructure observations indicate that in the S04 material the pretreatment applied produces a highly deformed structure containing only coarse constituent particles of the primary phases. On the other hand, an additional dense dispersion of fine precipitates (cubic a-Al 15 (Mn, Fe) 3 Si 2 ) is present in the S40 sheet due to the annealing at 450 8C used in that case.…”

Effect of Si and Fe on the Recrystallization Response of Al-Mn Alloys with Zr Addition

“…The alloy A (Fe) with more Fe than Si contained orthorombic Al 6 (Mn,Fe) and cubic α-Al 12 (Mn,Fe) 2 Si phases, while in the alloy B (Si) containing more Si, there was a mixture of cubic α-Al 12 (Mn,Fe) 2 Si and hexagonal α-Al 15 (Mn,Fe) 3 Si 2 phases. This observation corresponds with the results of Westermann [20], Cama et al [21], Slámová et al [22], and Cieslar et al [23].…”

Homogenization of a twin-roll cast thin Al–Mn strip

“…Hence, supersaturation of the aluminium matrix with Mn may be substantial in thin Al-Mn strips and could pose a number of problems during thermomechanical processing. A homogenization anneal makes a critical contribution by allowing the precipitation of excess Mn in solution before further processing [20]. The present work was undertaken to identify a sound homogenization practice for thin Al-Mn strips.…”