Microstructural Evolution and Mechanical Properties of Nb-Ti Microalloyed Pipeline Steel

  • Liang-yun Lan
  • Chun-lin Qiu
  • De-wen Zhao
  • Xiu-hua Gao


The correlation between microstructures and mechanical properties of a Nb-Ti microalloyed pipeline steel was investigated. The results revealed that with decreasing the finish rolling temperature and the cooling stop temperature, the matrix microstructure was changed from quasi-polygonal ferrite to acicular ferrite, as a result of improvement of both strength and low temperature toughness. By means of electron backscattered diffraction observation, an effective acicular ferrite packet contained several low angle boundaries or subboundaries plates which made important contributions to improvement of strength. It was found that many fine quasi-polygonal ferrite grains with high angle boundaries as the toughening structure were introduced into the acicular ferrite matrix to refine effective grain size and improve the toughness.

Key words

pipeline steel acicular ferrite mechanical property electron backscattered diffraction 


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Copyright information

© China Iron and Steel Research Institute Group 2011

Authors and Affiliations

  • Liang-yun Lan
    • 1
  • Chun-lin Qiu
    • 1
  • De-wen Zhao
    • 1
  • Xiu-hua Gao
    • 1
  1. 1.State Key Laboratory of Rolling and AutomationNortheastern UniversityShenyang, LiaoningChina

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