Analysis of sea test results of underwater wet multi-pass welding of DH36

In this paper, underwater wet manual multi-pass welding of different joint types was successfully completed through the diver welders after training. Butt joints in the flat position, lap joints in the horizontal and vertical positions, and T-joints in the vertical and flat positions were obtained under 11 m and 22 m water depths in the Bohai Sea. The test results indicate that all of the indexes of the joints welded at 11 m and 22 m water depths meet the requirements of the Class B Weld according to AWS D3.6 M: 2010. Compared with the joints welded at 11m water depth, the microstructures in the weld seam obtained at 22m depth have much more block ferrite and less amounts of acicular ferrite. The coarse-grained heat-affected zones of the joints at the two water depths are mainly composed of lath martensite.