Journal of Northeastern University Natural Science ›› 2020, Vol. 41 ›› Issue (6): 801-806.DOI: 10.12068/j.issn.1005-3026.2020.06.007

• Materials & Metallurgy • Previous Articles     Next Articles

Microstructure and Mechanical Properties of V-N Microalloyed X80 High Deformability Pipeline Steel

WANG Ming-ming, GAO Xiu-hua, DU Lin-xiu, ZHANG Da-zheng   

  1. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China.
  • Received:2019-11-20 Revised:2019-11-20 Online:2020-06-15 Published:2020-06-12
  • Contact: GAO Xiu-hua
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Abstract: The dynamic continuous cooling transformation behavior of undercooled austenite in a V-N microalloyed steel was studied by means of thermal simulation test machine. Furthermore, the rolling and cooling process parameters of V-N microalloyed X80 high deformability pipeline steel were designed and the relationship between microstructure and mechanical properties was analyzed. The dynamic CCT curve shows a separation of high temperature transformation region and intermediate temperature transformation region, and the transformation ranges are 637~728℃ and 441~601℃, respectively. When the cooling rate is in the range of 10~20℃/s, the microstructure mainly consists of acicular ferrite. The microstructure of V-N microalloyed pipeline steel is dominated bypolygonal ferrite and acicular ferrite. Yield strength, tensile strength, uniform elongation and -20℃ Charpy impact energy are 603MPa, 724MPa, 11.1% and 214J, respectively. These meet the requirements of X80 pipeline steels according to the API Spec 5L specification that the produced pipeline steel should have a good combination of strength and ductility.

Key words: V-N microalloying, pipeline steel, high deformability, microstructure, mechanical property

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