<abstract xmlns="http://www.w3.org/1999/xhtml"><p>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.</p></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.

Microstructure Evolution and Mechanical Properties of Underwater Dry Welded Metal of High Strength Steel Q690E Under Different Water Depths

Polish Maritime Research

This work is licensed under the Creative Commons Attribution 4.0 International License.

Q690E high strength low alloy (HSLA) steel has been intensively applied in maritime engineering. Also, the underwater dry welding (UDW) technique has been...

Microstructure Evolution and Mechanical Properties of Underwater Dry Welded Metal of High Strength Steel Q690E Under Different Water Depths

Published Online: Dec 24, 2020

Page range: 112 - 119

DOI: https://doi.org/10.2478/pomr-2020-0071

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

© 2020 Kun Sun et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Microstructure Evolution and Mechanical Properties of Underwater Dry Welded Metal of High Strength Steel Q690E Under Different Water Depths

Published Online: Dec 24, 2020

Page range: 112 - 119

DOI: https://doi.org/10.2478/pomr-2020-0071

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

© 2020 Kun Sun et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

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