Lateral Growth Rate of Cells in Melt

Growth process of delta-phase was studied during the solidification of carbon steel. Through analyzing the solute diffusion around cylindrical crystals in the melt, the mathematic representation of lateral growth rate of cylindrical crystals was confirmed; the calculation and analysis of lateral growth rate were carried out. In order to validate the theoretical calculation and analysis, the growth process of delta-phase during the solidification was in-situ observed using a confocal scaning laser microscope (CSLM) and the growth rates were measured through CSLM images. The results show that lateral growth rates of delta-phase in the carbon steel first rapidly decrease with the increase of the radius of the cylindrical crystal, and then slowly fall down or maintain invariable. The radius of delta-phase is the primary factor to affect the growth rate. The higher the temperature gradient is, the bigger the growth rate is. However, the effect of the temperature gradient is feeble. Good correlation is obtained between theoretical analysis and experiment results in absolute values of lateral growth rate and change rule.