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

A sound homogenization practice was investigated for thin Al-Mn strips. The structure in the as-cast state reveals features typical of rapid solidi. cation. The impact of subsequent hot rolling of the just solidified strip in the caster roll gap is also evident. A homogenization treatment makes a critical contribution by allowing the precipitation of excess Mn in solution. However, homogenized thin Al-Mn strips suffer coarse surface grains owing to the pinning of low and/or high angle grain boundaries by the. ne dispersoids. However, homogenization improves the response to a subsequent annealing treatment in a profound way. The strip sample processed without a homogenization treatment softens very slowly, retaining high strength levels even after 3 h at 375 degrees C. In contrast, the homogenized strip samples soften fully when annealed at temperatures below 350 degrees C. Homogenization at the cast gauge is identified as the best practice, as prior cold rolling does not improve the grain structure or accelerate the softening behaviour of thin Al-Mn strip. (c) 2008 Elsevier B.V. All rights reserved.