凝固速率对定向凝固50W600无取向硅钢固液界面稳定性和枝晶间距的影响

Effects of solidification rate on solid-liquid interface stability and dendrite arm spacing of directional solidified 50W600 non-oriented electrical steel

采用ZMLMC超高梯度定向凝固装置,研究了5种凝固速率(10、35、80、150和450μm/s)对定向凝固50W600无取向硅钢的固液界面稳定性转变规律和一次、二次枝晶间距的影响。研究结果表明,在特定的温度梯度下,随着凝固速率的增加,定向凝固的固液界面由胞状晶转变为胞状枝晶,再转变为细小的树枝晶。随着凝固速率的增加,定向凝固组织的枝晶形貌逐渐细化,一次和二次枝晶间距逐渐减小,且与冷却速率之间都符合指数关系:λ1=151.73×(G L·R)-0.31,λ2=22.07×(G L·R)-0.44。当冷却速率达到4.275℃/s时,一次、二次枝晶间距分别为112μm、14.1μm。

Under the conditions of certain temperature gradient and different solidification rate, the directional solidification experiment of non-oriented electrical steel 50W600 was carried out. The microstructure of 50W600 steel was also analyzed in different solidification rate. The result shows that the solid/liquid interface of the steel undergoes an evolution from cellular, cellular dendrite and finally to fine dendrite morphologies. The dendrite refines gradually and the distance between dendrites decreases greatly with the increase of solidification rate. The relation between primary and secondary dendrite arm spacing and cooling rate are A1 = 151.73 X （ GL R） -o.31 and A2 = 22.07 x （ GL R） -o.44, respectively. When the cooling rate is 4. 275 C/s, the values of AI and A2 are 112 pLm and 14.1 i.tm, respectively.