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 Development of rutilbased underwater electrode in accordance with AWS A5.35  Welding in real underwater conditions  Microstructural and mechanical characterization of allweld metal Figure A. Flowchart of the study Purpose: In this study, the microstructure and mechanical properties of the underwater welding electrodes, which was developed for the first time in Turkey in accordance with the AWS A5.35 standard, were investigated by performing the all-weld-metal tests in atmospheric and real underwater conditions. Theory and Methods: Low alloyed S355J2+N plates with the dimensions of 20x150x400mm were joined at atmospheric and real underwater condition using the Ø4 mm rutile based electrodes classified in accordance with AWS A5.1 and AWS A5.35 standarts. The underwater welds were performed in real sea atmosphere at the depth of 4 m in İstanbul, Turkey. The plates joined in both under water and atmosphere were subjected to the destructive tests (microstructure, microhardness, Charpy impact and tensile) and non-destructive tests (visual and radiographic tests) specified in accordance to AWS A5.35 standard and the results were compared. Results:No indication was found as a result of visual and radiographic inspection of the atmospheric welds, however, some porosity and slag inclusions which are not exceeding the acceptance criteria of AWS D3.6 were found in the plate joined underwater. Compared to atmospheric welds, It was found that the volume fraction of the annealed areas in the plate joined underwater were less and accordingly, the columnar zone are more. The width of HAZ for underwater welds was observed two times less than atmospheric welds. The hardness values of underwater welds were found to be 6-8% higher than atmospheric welds. Morever, there was no significant change in the yield and tensile strenght of plates joined in both condition. However, % elongation for underwater welds were found %48 less than atmospheric welds. Likewise, the Charpy impact values of underwater welds performed at -2°C and -20°C were found to be 22% and 14% lower than atmospheric welds, respectively. Conclusion:Although welds made with the speacial coated rutile-based underwater electrodes developed for the first time in Turkey have lower ductility compared to atmospheric welds, it has been observed that they met with the min requirements of AWS A5.35 Level 1.

In this study, AH36 steel plates which are commonly used in the hull of ships and in the construction of tanks in marine industry, were butt welded underwater by using shielded metal arc welding method and E6013 (GeKaTec UW E6013) rutile electrodes. Welding operations were carried out by expert industrial divers at a depth of 4 meters in a real sea environment. The plates were first subjected to non-destructive testing tests in accordance with the requirements of the AWS D3.6 standard. Then, hardness, Charpy impact, bending and tensile tests were performed to determine the mechanical properties of the welded plates joined under water, and the results were interpreted together with the microstructural transformations that occurred in the weld area.