平面流铸制备非晶薄带熔潭三维流动换热特性的研究

Study on Three Dimensional Flow Heat Transfer Characteristics of Amorphous Thin Strip Molten Pool Prepared by PFC

为了研究平面流铸制备非晶薄带过程中熔潭特性沿宽度方向的分布,建立了熔潭形成三维计算模型,应用有限体积法求解控制方程获得熔潭三维流场、温度场以及与冷却辊的换热特性。结果表明:熔潭与非晶薄带成型过程呈明显三维分布,熔体速度与温度分布沿宽度方向不同;非晶薄带在边缘向下弯曲,产生翘曲褶皱;熔潭长度在中部大于两端,中部的合金液冷却速率明显小于两端;熔潭中部的周围气流速度大于两端,但轴向热聚焦效应大于与空气的对流换热,造成冷却辊轴向温度存在明显差异,中部高于两端。综合冷却辊沿轴向的温度非均匀分布以及熔潭长度差异,在宽型非晶薄带制备过程需加强中部的换热,防止带体晶化产生脆性缺陷。

In order to study the distribution of molten pool characteristics along the width direction in the process of amorphous thin strip by plane flow casting(PFC),a three-dimensional calculation model of the molten pool formation was established.The three-dimensional flow field,temperature field and heat transfer characteristics with cooling roller were obtained by using finite volume method.The results show that the forming process of the molten pool and amorphous thin strip is obviously three-dimensional distributed,and the distribution of melt speed and temperature is different along the width direction;amorphous thin strip bends downward in the edge,resulting in warping fold;the length of the molten pool is larger in the middle than that in the two ends,and the cooling rate of the alloy in the middle is obviously smaller than that in the two ends;the air velocity in the middle of puddle is larger than that in the two ends,but the axial heat focusing effect is greater than the convective heat transfer with air,the axial temperature of cooling roller is significantly different,and the middle part is higher than the two ends.According to the temperature distribution along the axis of the cooling roller and the length difference of the melting pool,it is necessary to strengthen the heat exchange in the middle of the preparation process of the wide amorphous strip,so as to prevent the brittleness defects caused by the crystallization of the strip.