Solidification cooling rate and as-cast textures of low-carbon steel strips

The δ-ferrite dendrite structures, the as-cast ferrite grain morphology, the EBSD microscopic orientation characteristics and the macroscopic crystallographic textures of different low-carbon steel strips were investigated and the solidification cooling rates were deduced from the measured secondary dendrite arm spacings. With the decease in the solidification cooling rate, the widmanstatten ferrite grains become evidently coarsening and show much preferred growth characteristics. In all these as-cast steel strips, the orientation component {1 1 1} 〈u v w〉〈u v w〉 is stronger than {0 0 1} 〈u v 0〉〈u v 0〉, and the former component shows a roof-shape variation with the decrease of solidification cooling rate, and reaches the maximum intensity at about 2.0 K s−1. It was found by the EBSD measurement that the inclusion particles precipitated during post-solidification cooling more frequently appear in the {0 0 1} 〈u v 0〉〈u v 0〉-oriented α-ferrite grains rather than in the {1 1 1} 〈u v w〉〈u v w〉-oriented ones, which suggests that the inclusions are detrimental to the preferred nucleation/growth of {1 1 1} 〈u v w〉〈u v w〉-oriented α-ferrite grains. The δ-ferrite columnar dendrites with low density inclusions formed at a slow solidification cooling rate are beneficial to the formation of a strong {1 1 1} 〈u v w〉〈u v w〉 as-cast texture in low-carbon steel strips.