Hot working of AA10 - Relating the microstructural and textural developments

An aluminum alloy AA1050 was deformed in plain strain at different hot work ing conditions. An increase in temperature or a decrease in strain rate red uced the relative drop in cube {001} [100] and the relative increase in rol ling texture components of Cu {112}[111] and S {231}[346], especially appar ent at the higher strain. Along with such textural changes, significant dif ferences in hot worked microstructures were observed. The two distinct micr ostructural features, as observed by polarized light optical microscopy, we re grain boundary serrations (GBS) and in-grain inclined lines (IIL), typic ally observed at an approximate angle of 35 degrees with rolling direction (RD). At higher temperatures and lower strain rates, and correspondingly lo wer Zener-Holloman factors (Z approximate to 10(9)-10(10) s(-1)), coarse bu t nearly equiaxed grain interior substructures and GBS were observed. Inter estingly, orientation imaging microscopy (OIM) clearly showed insignificant /non-noticeable differences between the substructures of different orientat ion components. An increase in Z aligned the grain-interior low angle bound aries at an angle of approximately 35 degrees with RD and at higher Z (Z ap proximate to 10(12)-10(13) s(-1)) the main microstructural feature was the IILs. Development of in-grain long range misorientation (LRM) was estimated to be the mechanism behind the optical visibility of the IILs. The appeara nce of IILs had two apparent effects-first the substructures of different o rientation components were different, and secondly the stability of cube gr ains dropped noticeably. Generalizing the IILs or 35 degrees inclined cell walls as plastic instabilities or strain localizations, the observed differ ences in their relative appearance at different deformation conditions and/ or texture components could be explained. When formation of such strain loc alizations are considered as "necessary" for the reorientation of grain seg ment(s), the cube stability at low Z deformation could also be understood. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.