In order to achieve weight saving and improved performance in shipbuilding, the material thickness has reduced to plates as thin as 4 mm providing the structure has sufficient strength. These thin panels distort severely during welding which adds significantly to the cost of the fabrication process through the time spent on straightening and rework. To minimise these costs two approaches have been taken. The first approach is to study the effect of the welding process on the distortion levels. The process currently used in ship building is submerged arc welding. A comparison has been made between the heat input, melting efficiency, distortion level and microstructure of the SA process against DC MAG, pulsed MAG, cold metal transfer, laser hybrid and autogenous laser welding process. The results of the comparison show a direct correlation between the welding process heat input and the distortion level. The second approach has been to apply Stress Engineering (SE) techniques in combination with these different welding methods. SE in welding refers to the application of stress fields around the weld zone to control and or manipulate the welding stresses and therefore distortion. In this application the SE techniques that have been applied are thermal tensioning by heating Thermal Tensioning by Cooling. Both of these methods enable flat welds to be produced in 4mm plate using some of the higher heat input but lower cost welding processes.
Distortion mitigation in welded ship panels
2008
11 Seiten, 9 Bilder, 3 Tabellen, 14 Quellen
Conference paper
English
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