Influence of Starting Microstructure on Texture Development in Cold Rolled and Annealed Low Carbon Steel Strip

Abstract

The effect of initial microstructure on the recrystallization behaviour and texture development of low carbon (LC) steel was investigated. Steel strip samples (0.05 wt.% C) of 2 mm in thickness were heat treated to produce a microstructure consisting predominantly of either polygonal ferrite or acicular ferrite. Samples were cold rolled 50, 70 and 90% reduction then annealed for various times in the temperature range 580-640 oC. The microstructures and textures produced by deformation and annealing were studied by optical microscopy and electron backscatter diffraction in the SEM. The initial microstructure was found to have a substantial influence on the rate of recrystallization and final texture. It was found that polygonal ferrite recrystallizes more rapidly than acicular ferrite with the former generating the strongest <111>//ND recrystallization texture. The results are examined within the framework of improving the formability of LC steel produced by direct strip casting whereby controlled thermal and mechanical processing prior to cold rolling and annealing can generate the same types of initial microstructures, as studied in this work.