东北大学学报（自然科学版）

东北大学学报:自然科学版 ›› 2017, Vol. 38 ›› Issue (12): 1696-1701.DOI: 10.12068/j.issn.1005-3026.2017.12.006

• 材料与冶金 • 上一篇    下一篇

超快冷工艺对钢板心部异常带状组织的抑制作用

叶其斌， 谢谦， 刘振宇， 王国栋   

  1. (东北大学 轧制技术及连轧自动化国家重点实验室， 辽宁 沈阳110819)
  • 收稿日期:2016-06-16 修回日期:2016-06-16 出版日期:2017-12-15 发布日期:2018-01-02
  • 通讯作者: 叶其斌
  • 作者简介:叶其斌(1977-)， 男， 福建浦城人， 东北大学博士后研究人员； 刘振宇(1967-)， 男， 内蒙古赤峰人， 东北大学教授， 博士生导师; 王国栋(1942-)， 男， 辽宁大连人， 东北大学教授， 博士生导师， 中国工程院院士.
  • 基金资助:
    国家重点研发计划项目(2016YFB0300605)； 国家自然科学基金资助项目(51674081).

Effect of Ultrafast Cooling on Preventing Abnormal Microstructural Banding at Centerline of Steel Plate

YE Qi-bin， XIE Qian， LIU Zhen-yu， WANG Guo-dong   

  1. The State Key Laboratory of Rolling and Automation， Northeastern University， Shenyang 110819， China.
  • Received:2016-06-16 Revised:2016-06-16 Online:2017-12-15 Published:2018-01-02
  • Contact: YE Qi-bin
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摘要： 采用OM、TEM和EMPA方法对比研究了超快冷工艺及终轧温度对355MPa级钢板心部异常带状组织的影响.结果表明，950℃高温终轧及超快冷钢板(UC1钢)心部带状组织完全消失，900℃终轧及超快冷钢板(UC2钢)心部则形成了微弱带状组织，而轧后15℃/s层流冷却钢板(LC钢)心部则形成了包括马氏体/奥氏体低温相的严重带状组织.热力学计算显示，钢板心部偏析降低铁素体相变温度144℃，从而提高消除带状组织所需临界冷速到8℃/s.温度计算得到UC1和UC2钢板心部冷速分别达12.1和13.4℃/s，而LC钢板心部冷速只有5.5℃/s，表明超快冷足以抑制心部带状组织，但降低终轧温度削弱了这个效果，而层流冷速则无法抑制带状组织.

关键词: 超快冷, 终轧温度, 心部带状组织, 成分偏析, 临界冷速

Abstract: The abnormal microstructural banding at centerline was compared among three steel plates of 355 MPa grade using OM， TEM and EPMA， and the effects of ultrafast cooling (UFC) and finish rolling temperature (FRT) were discussed. It was found that UFC was effective to suppress banding in centerline segregation zones， as the bands were entirely disappeared in UFC steel with FRT at 950℃ (UC1 steel)， comparing with the feeble bands in UFC steel with FRT at 900℃(UC2 steel). In contrast， severe bands consisting of martensite/austenite constituent (M/A) were observed in a conventional laminar-water cooled steel (LC steel)with a cooling rates of 15℃/s. The thermodynamic calculation showed that the equilibrium temperature of austenite-to-ferrite transformation could be reduced by 144℃ in elements-rich centerline zone， increasing the critical cooling rate to 8℃/s for avoidance of banding. The simulated temperature indicated the cooling rate of 12.1 and 13.4℃/s at the mid-thickness of UC1 and UC2 steels， respectively， comparing with that of 5.5℃/s for LC steel. Therefore， UFC provides sufficient cooling capability for suppressing microstructural banding at plate centerline， while the lower FRT could offset the effect. In contrast， banding cant be prevented by exploring laminar-water cooling because of its relatively low cooling rate.

Key words: ultrafast cooling, finish rolling temperature, microstructural banding at centerline, chemical segregation, critical cooling rate

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