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Microstructure of Nb-Bearing Pipeline Steel with Improved Property Applying Ultrafast Cooling Process

Authors

  • Sheng-Jie Yao,

    Corresponding author
    1. School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264-209, China
    • School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264-209, China

      Email: shj_yao@yahoo.com.cn

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  • Lin-Xiu Du,

    1. State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110-004, China
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  • Guo-Dong Wang

    1. School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264-209, China
    2. State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110-004, China
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Abstract

X70 pipe line steel with high mechanical strength and high ductility can be achieved through hot rolling and ultrafast cooling process at a low cost. A large amount of nano-sized precipitates and dislocations are identified near the surface layer of the steel applying ultrafast cooling, which contribute immeasurably to the improvement of mechanical properties. In addition, high cooling rate decreases the mean distance of pearlite laminae, and massive ferrite grains characterized by curved grain boundaries and high dislocation density are also transformed as one of the typical microstructures in the samples applying ultrafast cooling process.

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