Implications of Accelerated Solidification Rates Seen in Belt Casting on Precipitation in Nb Bearing Steels

High temperature confocal microscopy (using cooling rates of 1 and 20 Cs-1) has been used in conjunction with segregation modeling (for cooling rates of 0.1-100 Cs-1) to understand the implications that high cooling rates, representative of that seen for belt casting, has on compositional in homogeneity and precipitation in high strength low alloy steels. Due to the increased level of segregation (and reduced back diffusion) precipitates are predicted, and shown, to form in the interdendritic solute rich regions at temperatures higher than would be expected under equilibrium conditions at the higher cooling rate. This results in a larger volume fraction of precipitates in samples held at 1000 C after being cooled at 20 Cs-1 compared to those cooled at 1 Cs-1.