Abstract
There are three main methods of underwater welding: dry, wet and intermediate between them, by using the local dry chamber. Due to low costs, the most common method is the wet welding with the use of covered electrodes. Water as a welding environment carries out a lot of problems. The first is limited visibility and instability of the welding arc. The biggest problem during underwater welding is high susceptibility to cold cracking, resulting from the increased diffusible hydrogen content in deposited metal and high stress values.In the work, Tekken joints from S355J2C+N steel were made in air and in water environment. The joints were subjected to non-destructive visual (VT) and penetrant (PT) tests. Then, macroscopic tests and hardness measurements were performed. The results confirm the literature reports that the water environment causes an in-crease in hardness in the heat affected zone (HAZ), which promotes the formation of cracks in welding joints.
Highlights
Tekken tests carried out allowed to state that S355J2C+N steel is characterized by good weldability during welding in the air and bad in underwater conditions
The welds made of welded joints in the air were devoid of welding imperfections, while samples made in the water environment contained cracks that separated the joint into two fragments
It has been proven that the water environment has contributed to a significant increase in hardness in both the heat affected zone (HAZ) and the weld
Summary
There are three basic methods of welding in the water environment [1÷4]: – wet welding – due to the low costs most often used, it does not require specialized equipment, during the process the area of the formed joint and the electric arc are in contact with the water environment; – dry welding – the most expensive method of underwater welding, which results from the need to build special chambers that isolate the welder, joint area and electric arc from the environment, the method occurs in two varieties – isobaric (pressure equal to air pressure) and hyperbaric (pressure resulting from welding depth); – welding with the local dry chamber – is an indirect method, isolated from the water is only the welding area with the electric arc, while the welder is in the water, the method allows to obtain better joints than in the case of dry welding, due to the arc not being visible to the welder does not find as wide application as the two above.
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