High temperature confocal microscopy (using cooling rates of 1 and 20 °C s−1) has been used in conjunction with segregation modeling (for cooling rates of 0.1–100 °C s−1) to understand the implications that high cooling rates, representative of that seen for belt casting, has on compositional inhomogeneity 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 °C s−1 compared to those cooled at 1 °C s−1. This paper highlights the implications that increasing the solidification rate (such as those seen in near net shape casting) has on the precipitation kinetics of high strength low alloy steel (Nb bearing steel). Due to the high microsegregation and the reduced back diffusion seen in the near net-shape castings, Nb precipitates are formed much sooner in the steel making process, and therefore at higher temperatures. This leads to fewer but larger precipitates.

+More

precipitation kinetics interdendritic solute net shape temperature confocal microscopy fraction compositional inhomogeneity and precipitation segregation modeling back diffusion precipitates

Claire Davis,Carl Slater, Andrii Kostryzhev, Olexandra Marenych,.Implications of Accelerated Solidification Rates Seen in Belt Casting on Precipitation in Nb Bearing Steels. 89 (2),.

Claire Davis, et al."Implications of Accelerated Solidification Rates Seen in Belt Casting on Precipitation in Nb Bearing Steels" 89

Claire Davis,Carl Slater, Andrii Kostryzhev, Olexandra Marenych,"Implications of Accelerated Solidification Rates Seen in Belt Casting on Precipitation in Nb Bearing Steels"