Dissimilar underwater wet welding of HSLA steels

Jacek Tomków,Grzegorz Rogalski,Dariusz Fydrych

doi:10.1007/s00170-020-05617-y

Jacek Tomków, Grzegorz Rogalski + Show 1 more

Open Access

https://doi.org/10.1007/s00170-020-05617-y

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Abstract

The high-strength low-alloy S460ML and S460N steels were chosen for underwater wet welding of dissimilar T-joints using covered electrodes. For improving the quality of joints, the temper bead welding (TBW) method was used. The application of TBW in pad welding conditions has been investigated earlier but the possibility of usage of this technique in welded joints was not analyzed. The main aim of the study was to check the influence of TBW on the hardness and structures of the heat-affected zone (HAZ) of dissimilar T-joints made in the underwater conditions. The experiments conducted showed that the technique used can reduce the susceptibility to cold cracking by decreasing the hardness in HAZ, which is a result of changes in its structure. The TBW technique reduced the hardness in the HAZ of the S460N steel by 40–50 HV10 and in S460ML by 80–100 HV10. It was also found that the changes in S460ML and S460N were much different, and therefore, the investigated technique can provide better results in the steel characterized by lower carbon equivalent CeIIW.

Highlights

The number of offshore steel constructions is increasing every year
The results of the experiments conducted in the present study showed that both materials, S460N and S460ML, were characterized by high susceptibility to cold cracking in the heat-affected zone (HAZ), as was found in the specimens made without the temper bead welding (TBW) technique
The results proved that the CeIIW values cannot be considered as good weldability indicator for wet welding in water environment

Summary

Introduction

The number of offshore steel constructions is increasing every year. One of the reasons is the oil and gas sources present under the sea, which are being explored more and more. New methods of localization are still developing, for example, a method based on changes in the frequency spectrum [8]. More than 50% of Faculty of Mechanical Engineering, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland operational offshore platforms in the Norwegian Continental Shelf and the UK Continental Shelf have exceeded their design life [9]. Engineering is trying to make exploitation time longer, which can reduce the cost of the potential repairs or enable changing the constructions to new ones. This could be done in the stage of design, production, or repair

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