电磁搅拌作用下CoCrMo合金熔模铸件凝固细晶研究  

Grain Refinement of Solidification Structure of CoCrMo Alloy Investment Castings under Electromagnetic Stirring

作　　者：但泽宇 赵江涛 李彦华 邓元鑫 张云虎[1] 宋长江[1] DAN Ze-yu;ZHAO Jiang-tao;LI Yan-hua;DENG Yuan-xin;ZHANG Yun-hu;SONG Chang-jiang(Center for Advanced Solidification Technology,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;Wuxi CastPro Precision Co.,Ltd.,Jiangsu Wuxi 214105,China)

机构地区：[1]上海大学先进凝固中心材料科学与工程学院,上海200444 [2]无锡卡仕精密科技有限公司,江苏无锡214105

出　　处：《精密成形工程》2023年第10期50-59,共10页Journal of Netshape Forming Engineering

基　　金：国家自然科学基金(52271034,51974183);云南省材料基因工程Ⅱ期(202302AB080020);上海市自然科学面上基金(22ZR1425000)。

摘　　要：目的研究电磁搅拌对CoCrMo合金熔模铸件晶粒尺寸的影响,解决熔模铸造CoCrMo合金铸件晶粒粗大的问题。方法将CoCrMo合金熔化后,在其凝固过程中分别施加不同工艺参数的电磁搅拌,并对其凝固后的组织进行表征分析。同时,采用有限元法对电磁搅拌在金属熔体中的电磁场和流场进行数值模拟。结果在不同的电磁搅拌参数下,CoCrMo合金铸件凝固组织出现了不同程度的细晶效果,浇道处的细晶效果优于铸件试棒处的。铸件试棒处的晶粒尺寸最小能控制在1mm以下,等轴晶率最高能提升至31%。数值模拟结果表明,在电磁搅拌过程中,铸件试棒的磁场、电流和洛伦兹力都呈周期性变化,铸件试棒内部的流速随搅拌时间的延长而增大,最后趋于稳定。结论电磁搅拌对CoCrMo合金的凝固组织产生了明显的细化效果,促进了柱状晶向等轴晶转变。电磁搅拌的时间越长,铸件凝固组织的细化效果越好,铸件厚大部位的细晶效果越显著。结合实验结果和数值模拟结果发现,在电磁搅拌过程中,熔体流动引发枝晶断裂是晶粒细化的主要原因,而电磁场促进异质形核为次要原因。The work aims to study the effect of electromagnetic stirring on the grain size of CoCrMo alloy investment cast-ings,and solve the problem of coarse grain size in investment cast CoCrMo alloy castings.After melting CoCrMo alloy,elec-tromagnetic stirring with different process parameters was applied during its solidification to characterize and analyze its solidi-fied structure.At the same time,the finite element method was used to numerically simulate the electromagnetic field and flow field of electromagnetic stirring in metal melts.Under different electromagnetic stirring parameters,the solidification structure of CoCrMo alloy castings exhibited varying degrees of fine-grained effect,and the fine-grained effect at the runner was better than that at the casting bar.The minimum grain size at the casting bar could be controlled below 1 mm,and the maximum equi-axed grain rate could be increased to 31%.The numerical simulation results indicated that during electromagnetic stirring,the magnetic field,current,and Lorentz force of the casting bar exhibited periodic changes.The internal flow rate of the casting bar increased with the prolongation of stirring time and eventually stabilizes.In conclusion,electromagnetic stirring has a signifi-cant refining effect on the solidification structure of CoCrMo alloy,promoting the transformation of columnar grains into equi-axed grains.The longer the electromagnetic stirring time,the better the refinement effect of the solidification structure of the casting.At the same time,electromagnetic stirring has a significant effect on grain refinement in thick areas of castings.Com-bining experimental and numerical simulation results,it is found that dendritic fracture caused by melt flow during electromag-netic stirring is the main reason for promoting grain refinement,while electromagnetic field promoting heterogeneous nucleation is the secondary reason.

关 键 词：熔模铸造 CoCrMo合金 晶粒细化 电磁搅拌 数值模拟 

分 类 号：TG244.3[金属学及工艺—铸造]