大钢锭A型偏析的模拟研究

Simulation of A-segregation in Large Steel Ingots

使用立体显微镜及深孔光纤投影仪对模拟大型钢锭内部液相对流与宏观组织的Pb-5Sn和NH_4CL-H_2O铸锭的A型偏析进行了研究.观察到A型偏析的两种形成机制.研究发现:(1)形成A型偏析的基本条件是较低的凝固速度与一定的水平温度梯度;(2)A型偏析的形貌取决于凝固速度与一次枝晶阵的取向;(3)可通过控制凝固速度,温度梯度,一次枝晶阵取向及高径比防止A型偏析.

The formation of A-segregation in ingot of Pb-5Sn and NH4Cl-H2O which are vised for simulating the liquid convection and the macrostructure of large steel ingots has been studied using stereo microscope and fiberlight projector. Two formation mechanisms of A-segregation have been found. The research revealed that:(1)the prerequisite for A-segregation formation are higher horizontal temperature gradient and lower solidification rate, (2) the morphology of A-segregation depends on solidification rate and fil'st dendritic orientation, (3) A-segreation can be prevented by controlling solidification rate, horizontal temperature gradient, primary dendritic orientation and H/D of ingot.