Heat Treatment of Metals ›› 2020, Vol. 45 ›› Issue (6): 104-107.DOI: 10.13251/j.issn.0254-6051.2020.06.023

• MICROSTRUCTURE AND PROPERTIES • Previous Articles     Next Articles

CCT curves and properties of low yield rario high strength weathering steel

Yao Jitan, Sun Li, An Huilong, Xin Ruishan, Pan Jin, Zhao Yanqing   

  1. HBIS Group Technology Research Institute, Shijiazhuang Hebei 050023, China
  • Received:2019-12-20 Online:2020-06-25 Published:2020-09-02

Abstract: Continuous cooling transformation (CCT) curves of a low yield ratio high strength weathering steel were plotted by means of expansion method combined with metallographical and hardness methods, and the mechanical properties and corrosion resistance of this steel were studied. The results indicate that the tensile strength of the tested steel reaches 575 MPa with 0.75 yield ratio, the impact property is excellent, and the corrosion resistance is obviously better than Q345B steel. When the tested steel after austenitizing is cooled to room temperature at a cooling rate of 0.1-100 ℃/s, its microhardness value increases from 131 HV0.5 to 218 HV0.5 with the increase of cooling rate. When the cooling rate is below 1 ℃/s, the microstructure of the steel is composed of ferrite and pearlite. When the cooling rate is in the range from 1 ℃/s to 20 ℃/s, the microstructure is composed of ferrite, pearlite and bainite. When the cooling rate is in the range from 20 ℃/s to 100 ℃/s, the pearlite disappears and the microstructure is mainly composed of ferrite and bainite.

Key words: low yield ratio, high strength weathering steel, CCT curves

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