Deflective Dendrite Growth Of Fe-C Based Alloys In The Presence Of Fluid Flow

During solidification process of metals, the buoyancy flow induced by temperature and density difference and the natural or forced convection caused by solidification shrinkage are unavoidable.The flow fluid affects the heat and mass transfer in metals, changes the temperature and concentration field inside and further influences the final solidification structures. Therefore, it is necessary to study the mechanics of dendrite growth in the presence of flow in order to optimize the operation and process parameters to obtain the expected grain structures and properties.In the presence paper, the dendrite tip growth kinetics model for Fe-C binary/ternary alloy in flow field are developed based on the solidification fundamentals theories. Combining with Cellular Automata method, the deflective growth behaviors of dendrites in the fluid flow field are deeply discussed. The follow results are obtained:(1) Dendrite tip growth rate increases with flow intensity, the increase of the angle between the directions of dendrite growth and fluid flow, and the increase of diffusion coefficient in liquid. While the tip growth rate decreases with the increase of growth restriction parameter for each solute mjwoj(kj-1) and the increase of Gibbs-Thomson coefficient.(2) The envelopes of multi-grains evolve towards fluid flow direction in the presence of fluid flow. Increasing the fluid flow velocity and the growth restriction parameter for each solute mjw0j(kj-1) make the dendrites growth towards upstream direction. As a result, it increases the dendritic deflection angle θ. However the increase of cooling rate slightly decreases the deflective growth. Totally, the influence fluid flow intensity is dominative while the effect of cooling rate is much weak.(3) Using the dendrite tip growth kinetics model for Fe-C ternary alloy, the predicted dendritic deflection angles in flow field for varied carbon concentration fit better with the experimental data of Esaka and Okano for Fe-C multi-component alloys, combining with Cellular Automata method.