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MICROSTRUCTURE EVOLUTION AND MECHANICAL PROPERTIES OF UNDERWATER DRY WELDED METAL OF HIGH STRENGTH STEEL Q690E UNDER DIFFERENT WATER DEPTHS

Abstract

Q690E high strength low alloy (HSLA) steel has been intensively applied in maritime engineering. Also, the underwater dry welding (UDW) technique has been widely used to repair important offshore facilities. In this paper, joints of Q690E steel were fabricated through single-pass underwater dry welding at three pressures (0, 0.2, and 0.4 MPa). To study the effect of the pressure on the microstructure and mechanical properties of the UDW joint, an optical microscope (OM) and scanning electron microscope (SEM) were used to observe the microstructure and fracture morphology of the welded joints. The electron backscattered diffraction (EBSD) technique was used to analyse the crystallographic features and the crystallographic grain size of the ferrites. The proportion of acicular ferrite (AF) in the UDW joints and the density of low-angle boundaries increase dramatically with the increasing depth of water. The weld metal of UDW-40 shows higher strength because more fine ferrites and low-angle boundaries within UDW-40 impede the dislocation movement.

Keywords:

underwater dry welding, high strength low alloy steel, water depth, microstructural evolution, mechanical property

Details

Issue
Vol. 27 No. 4(108) (2020)
Section
Latest Articles
Published
24-12-2020
DOI:
https://doi.org/10.2478/pomr-2020-0071
Licencja:
Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Open Access License

This journal provides immediate open access to its content under the Creative Commons BY 4.0 license. Authors who publish with this journal retain all copyrights and agree to the terms of the CC BY 4.0 license.

 

Authors

  • Kun Sun

    School of Mechanical and Automotive Engineering, Guangdong Provincial Engineering Research Center for Special Welding Technology and Equipment, South China University of Technology, Guangzhou 510640
  • Yu Hu

    School of Mechatronic Engineering and Automation, Foshan University, Foshan 528000
  • Yonghua Shi

    School of Mechanical and Automotive Engineering, Guangdong Provincial Engineering Research Center for Special Welding Technology and Equipment, South China University of Technology, Guangzhou 510640
  • Baoyi Liao

    School of Mechanical and Automotive Engineering, Guangdong Provincial Engineering Research Center for Special Welding Technology and Equipment, South China University of Technology, Guangzhou 510640

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