Wet underwater welding is widely used for installation and repair ofvarious offshore structures and vessels, including pipelines, oil and gasoffshore platforms, submarines vessels, docks and other offshoreconstructions. To maintain structural integrity and the required durationof the service life, high-quality welding is critical. The mechanizedwelding with flux-cored wires could be used to improve the quality andproductivity of underwater welding. This study aims to improve thequality of wet underwater welding by development and testing fluxcoredwire with high-complex fluoride content.The developed wire of 1.6 mm diameter was tested in weldingapplications at a depth of 14 meters for butt-welding s355 steel platesof 10-12 mm thickness. On the basis of the thermodynamic analysis,the new chemical composition of flux-cored wire was developed. Thechemical composition is based on the rutile and complex-fluorideNa3AlF6. Because of decomposition and evaporation of complexfluoride Na3AlF6 the gaseous compounds NaF, AlF3, AlF2, AlF areformed, and they are changing the chemical constitution of gas-vaporbubble atmosphere which was generated by decomposition of water bythe welding arc.The application of the wire provided the reduction of porosity and slaginclusions in the weld, as well as the improvement of mechanicalproperties. Additionally, the flux-cored wire with high-fluoride contentallowed stabilizing the welding arc in a wet environment and improvingthe penetration. As a result, the metal transfer characteristics ofelectrode metal improved.
展开▼
