On the Macrosegregation of Continuous Casting of High Carbon Steel Billet with Strand Reduction Process

Abstract

A mathematical model of the macrosegregation of continuous cast high carbon steel billet was developed based upon a representative volume element, considering the flow of enriched liquid, solidification rate, and solidification shrinkage as well. It was found that a lower casting velocity, higher cooling intensity, and shorter solidification interval positively contributed to the inhibition of macrosegregation in a continuously cast billet when a mechanical reduction process was not applied. A numerical expression for the relative flow velocity of liquid was further proposed incorporating such aspects as casting velocity, densities of different phases, and the variation of cross section areas as well. The analysis based on this numerical expression indicated that the overall effect of the reduction process on the macrosegregation of billets depended not only on the reduction zone but also on the reduction amount and its distribution for the active reduction rolls. The test results of further practical plant trials demonstrated a reasonable agreement with the predictions obtained from the proposed numerical model, indicating the reliability of this analysis model to be employed for the continuous casting of high carbon steel billet with strand reduction process.

Homogenization Path Based on 250 mm × 280 mm Bloom under Mixed Light and Heavy Presses: Simulation and Industrial Studies

“…When the pulling speed is less than or equal to 0.47 m/min, the solidification endpoint occurs before the pressable unit of the drawing and straightening machine. As a result, the liquid core length is too small to compensate for the solidification shrinkage by soft pressing down, and the theoretical shrinkage is 6.55 mm 2 . When the pulling speed is 0.52 m/min, the solidification endpoint occurs between the number two and number three drawing and straightening machines.…”

“…This results in an uneven chemical composition, which is difficult to eliminate or improve to a greater extent in subsequent rolling and heat treatments. As a result, this is the main problem affecting the internal quality of the billet [2,3].…”