FRACTURE TOUGHNESS OF FERRITIC STEEL -UNDERWATER WET WELDED

摘要

Life extension of structures, such as nuclear power plants or nuclear reactor internals could require recoveriesor mitigation actions due to aging phenomena. Such actions on steel structures many times has to be done usingwelds in wet environment, what would require special techniques like underwater wet welding.Shielded metal-arc welding is usually used in underwater wet welding. Once the welding electric arc is open,water dissociation occurs, producing oxygen, hydrogen, and characteristic welding gases. These producedchemical elements can be absorbed by the weld in underwater wet welding process and due to the fast cooling ofweld it is impossible to eliminate these welding gases. Higher levels of absorbed discontinuities are characteristicsof underwater wet welding. Cooling rate of underwater wet welding is faster than conventional air welding.Structures built using underwater wet welding must attend to special structural requirements.Results of fracture toughness of materials produced with high cooling rate and high level of inherentdiscontinuities, characteristic of underwater wet welding process, are presented in this paper. Materials used in thiswork were welded in depth condition of 0, 20, 40 and 60 meters of water column.