Microstructural evolution during recrystallization in hot rolled Aluminum Alloy 1050 Mohammed H. Alvi 1 , Sunwook Cheong 2 , Hasso Weiland 2 and Anthony D. Rollett 1 1 Materials Science and Engineering Carnegie Mellon University Pittsburgh, PA 2 Alcoa Technical Center, Alcoa Center, PA, 15069, USA Abstract The evolution of texture as a function of recrystallization has been characterized for hot-rolled AA1050. Samples prepared from a hot rolled sheet were annealed isothermally for sufficient time to allow complete recrystallization. The spatial orientation variation within the deformed microstructure of nucleation, growth and orientations of recrystallized grains is examined. The microstructural variation and texture evolution in the samples is observed by automatic indexing of Electron Back Scatter Diffraction (EBSD) patterns in a Scanning Electron Microscope (SEM). The effect of deformation texture on the evolution and growth of various recrystallization texture components is also analyzed by EBSD. The analysis is aimed at obtaining a correlation between the deformation microstructure, texture development and recrystallization kinetics in the hot-rolled condition. Introduction The microstructural evolution during annealing of rolled aluminum alloy is an important way of changing properties of the rolled sheets. The important forming properties can be restored after annealing of rolled sheets, allowing for the further reduction in thickness. The microstructural features of deformed and recrystallized regions differ considerably. While the dislocation content of a deformed grain is high thereby giving a large intragranular orientation spread, the recrystallized grains are characterized by low dislocation content having a small intragranular orientation spread. The main aspect analyzed in the present study is the intragranular orientation spread of deformed and recrystallized grains. The orientation spread is defined as the misorientation angle between all the points in a grain and Grain Orientation Spread (GOS) is the average value of orientation spread in a grain. The difference in GOS value for deformed and recrystallized grains provides an important way of partitioning the deformed and recrystallized regions in partially recrystallized and deformed samples scanned through Orientation Imaging Microscopy (OIM) based on automated Electron Back Scattered Diffraction (EBSD). Different methods have been analyzed previously for obtaining recrystallized fraction from EBSD data, namely Image Quality (IQ) and Confidence Index (CI). (1, 2) The main advantage of using GOS as a criterion is its independence from the user dependent settings affecting the IQ and CI value during the scanning of an area. The IQ and CI values can show a large variation on even on a single sample, whereas a single GOS value can be used for all recrystallized grains on different samples. The regions partitioned in this way can be further analyzed for texture evolution of deformed and recrystallized grains during annealing of deformed samples. Experimental Procedure The chemical composition of hot rolled Aluminum Alloy 1050 (AA1050) used in the present analysis is given in Table 1. Samples of size 20 were obtained from the hot rolled sheet and were annealed at and for time intervals ranging from 30 to for complete recrystallization of deformed samples. These samples were then polished with SiC carbides papers upto 1200 grade and mm mm mm 6 10 × × C o 375 s 1800 C o 400 m s µ 1 alumina suspension to prepare them for microhardness tests. On an average, 8 to 10 microhardness indentations were obtained on each sample with two samples 1