轻压下枝晶变形及溶质分布的试验模拟研究

通过丁二腈-水合金试验类比研究了连铸过程中的轻压下工艺。水冷强度1.2、0.6、0.3mL/s下,分别研究了不同固相分数和不同变形量对枝晶变形及溶质再分布的影响,并用示踪剂进行示踪。结果表明：实施轻压下时,大部分柱状晶发生弯曲变形,不再继续生长,此时二次枝晶和部分等轴晶快速长大;在溶液凝固早期,会形成凝固中心上升,凝固前沿下沉的对流,对凝固前沿进行充分的溶质交换,当这种对流减弱之后才能进行有效的轻压下操作;变形量对溶质分布的影响比较复杂,在变形量逐渐增大的过程中,首先形成负偏析,经过一个偏析为零的阶段后再形成正偏析,且偏析越来越严重,并且位于压下区间不同的区域,影响程度不一样。试验结果对研究轻压下对偏析的改善机理有意义。

Experimental Study on the Dendrites Deformation and Solute Distribution During Soft Reduction

The soft reduction process of continuous casting had been experimentally studied with succinonitrile-water alloys.The effects of the solid fraction and deformation amount on both the dendrites deformation and solute redistribution had been studied under the cooling intensity of 1.2,0.6,0.3mL/s respectively.At the same time,the tracer was also used.The results indicated that during the soft reduction process,most of the dendrites bended and stopped growing,while some secondary dendrites and part equiaxed crystal growed rapidly.In the early period of the solidification,convection rose at the central line and sinked at the solidification front and form an adequate solute exchange,only after it became weak can carry out the operation of soft reduction effectively.Deformation amount had a complex effect on solute distribution,with the deformation amount gradually increased,the negative segregation formed firstly,through a period of none segregation formation the positive segregation formed,and more and more seriously.The impact degree was not same in different soft reduction areas.These experimental results are helpful to the study of the center segregation improvement mechanism of soft reduction.