Heat Treatment of Metals ›› 2024, Vol. 49 ›› Issue (5): 124-129.DOI: 10.13251/j.issn.0254-6051.2024.05.020

• PROCESS RESEARCH • Previous Articles     Next Articles

Effect of quenching temperature on microstructure and properties of 690 MPa grade steel for pressure vessels with low welding crack sensitivity

Liu Chenxi1,2, Hu Xinming1,2, Ouyang Xin1,2, Xing Mengnan1,2, Wang Chu1,2   

  1. 1. State Key Laboratory of Metal Material for Marine Equipment and Application, Anshan Liaoning 114009, China;
    2. Iron and Steel Research Institute of Angang Group, Anshan Liaoning 114009, China
  • Received:2023-11-07 Revised:2024-03-29 Online:2024-05-25 Published:2024-06-28

Abstract: Microstructure evolution and mechanical properties of a 690 MPa grade pressure vessel steel with low welding crack sensitivity at different quenching temperatures were studied by means of optical microscope, scanning electron microscope, high-temperature confocal microscope, electronic tensile testing machine and fully automatic impact testing machine. The results show that the microstructure of the designed tested steel is mainly composed of granular bainite, lath bainite and ferrite after rolling and quenching at 820-970 ℃. Under a high-temperature confocal microscope, it is observed that during the quenching process at 970 ℃, when the temperature drops to 520 ℃, some grains begin to undergo shear transformation and form lath bainite. After quenching and tempering, part of the quenched microstructure is retained due to the genetic effect of the microstructure. When the quenching temperature rises to above 950 ℃, the strength level of the quenched and tempered tested steel can reach 690 MPa grade.

Key words: quenching temperature, steel for pressure vessel, high-temperature confocal microscope, bainite, properties

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