东北大学学报（自然科学版）

东北大学学报(自然科学版) ›› 2013, Vol. 34 ›› Issue (9): 1257-1260.DOI: -

• 材料与冶金 • 上一篇    下一篇

旋转电磁搅拌时机对GCr15轴承钢凝固组织的影响

郑金星，许秀杰，王恩刚，赫冀成   

  1. (东北大学材料电磁过程研究教育部重点实验室，辽宁沈阳110819)
  • 收稿日期:2013-04-28 修回日期:2013-04-28 出版日期:2013-09-15 发布日期:2013-04-22
  • 通讯作者: 郑金星
  • 作者简介:郑金星(1967-)，男，山东东营人，东北大学访问学者，山东工业职业学院副教授；王恩刚(1962-)，男，辽宁沈阳人，东北大学教授，博士生导师；赫冀成(1943-)，男，辽宁瓦房店人，东北大学教授，博士生导师.
  • 基金资助:
    国家自然科学基金资助项目(50834009)；山东省高等学校青年骨干教师国内访问学者项目.

Effects of Time of Applying Rotating Electromagnetic Stirring on the Solidification Microstructure of GCr15 Bearing Steels

ZHENG Jinxing， XU Xiujie， WANG Engang， HE Jicheng   

  1. Key Laboratory of Electromagnetic Processing of Materials， Ministry of Education， Northeastern University， Shenyang 110819， China.
  • Received:2013-04-28 Revised:2013-04-28 Online:2013-09-15 Published:2013-04-22
  • Contact: WANG Engang
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摘要： 通过石墨型铸造研究了旋转电磁搅拌时机对GCr15轴承钢凝固组织的影响.结果表明:在钢液凝固过程的不同时间段施加电磁搅拌，对轴承钢的凝固组织具有显著影响，越早施加电磁搅拌，磁泰勒数(表征磁场作用下强制流动的无量纲数)越大，钢液所受的电磁力越大，越有利于柱状晶向等轴晶转变；在0~05min时间段施加电磁搅拌，铸锭等轴晶率提高了52%.此外，电磁搅拌引起的钢液对流推动了凝固前沿枝晶的折断、熔断和游离，枝晶碎片在强烈对流作用下增殖并被带到熔体心部成为异质核心，凝固前沿的温度梯度减小，成分过冷增大，促进了柱状晶向等轴晶转变.

关键词: 轴承钢, 电磁力, 凝固组织, 过冷度, 磁泰勒数

Abstract: The effects of the time of applying rotating electromagnetic stirring on the solidification microstructure of GCr15 bearing steels were investigated via graphite mold casting. The results showed that imposing rotating electromagnetic stirring at different periods during the solidification process of the molten steel significantly influences the solidification microstructure of the bearing steel ingots. The sooner rotating electromagnetic stirring is imposed， the larger magnetic Taylor number (the characteristic nondimensional parameter to describe the forced convection by the magnetic field) is. Accordingly， the electromagnetic force generates remarkably in the molten steel， which indicates that the fluid flow is strong enough for the columnarequiaxed transition (CET). The equiaxed crystal ratio of the ingot increased to 52% when the rotating electromagnetic stirring is imposed during the period of 0~05min after the accomplishment of pouring. Furthermore， the fluid flow generated by rotating electromagnetic stirring promotes the breaking， melting and drifting away of the dendrites in the solidification front. The fragments of the dendrites proliferated and were brought to the centre of the molten pool which became the heterogeneous nucleus under the strong fluid convection. The constitutional supercooling degree increases with the decrease of temperature gradient which consequently in favor of the promotion of CET.

Key words: bearing steels, electromagnetic force, solidification microstructure, supercooling degree, magnetic Taylor number

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