双辊薄带振动铸轧机理及其仿真实验

摘要

A set of?160 mm×150 mm vibration casting machines were designed and manufac-tured in order to carry out the research on the product quality of twin roll strip casting processes.The effects of vibrations on the crystal nucleation and cast microstructure were studied.The distributions and growth rules of the cast microstructures in the solidification zones under the conditions of vibra-tion and non-vibration were compared and analyzed.It is pointed out that improving the vibration fre-quencies may effectively promote the grain refinement.At the same time,according to the require-ments of industrial experiments,a three-dimensional flow field-temperature field coupling finite ele-ment simulation model of molten pools was established by using CFD software.The results show that increasing the vibration frequencies and amplitudes may enhance the"mixing"effects of the cast roll-ing molten pools,which may promote the grain refinements and restrain the segregations.It is found that the solidification point positions(i.e.Kiss point height)are not distributed along the width direc-tion of the plates in the castrolling processes.As a result,the longitudinal inhomogeneous extensions are the direct factors to induce the cast rolling oblique cracks.And the Kiss point position will be moved up with the increase of the amplitudes and the frequencies.%针对双辊薄带铸轧过程存在的产品质量问题进行研究,设计制造了一套?160 mm×150 mm振动式铸轧机.研究了振动对结晶形核及其铸态组织的影响,对比分析了振动与非振动条件下凝固区铸态组织分布及其生长规律.指出提高振动频率能够有效促进晶粒细化.同时,按工业化实验要求,利用CFD软件建立了熔池的三维流场 温度场耦合有限元仿真模型,仿真结果表明,增大振频和振幅均能强化铸轧熔池场的"搅拌"效果,进而促进晶粒细化、抑制偏析.通过仿真还发现,铸轧过程中,凝固点位置(即Kiss点高度)沿板宽方向分布不均所导致的纵向不均匀延伸,是诱发铸轧斜向裂纹的直接因素,并且Kiss点位置会随振频和振幅的增大而上移.