Studies of welded joints

Studies of a welded joint were described. The joint was made as a result of the reconstruction of a truss and one of the possible means to make a repair. The studies were of a simulation character and were targeted at the detection of welding defects and imperfections that should be eliminated in a real structure. A model was designed and on this model the tests and examinations were carried out. The model was made under the same conditions as the conditions adopted for repair. It corresponded to the real object in shape and dimensions, and in the proposed technique of welding and welding parameters. The model was composed of five plates joined together with twelve beads. The destructive and non-destructive tests were carried out; the whole structure and the respective welds were also examined visually. The defects and imperfections in welds were detected by surface methods of inspection, penetration tests and magnetic particle flaw detection. The model of the welded joint was prepared by destructive methods, a technique that would never be permitted in the case of a real structure. For the investigations it was necessary to cut out the specimens from the welded joint in direction transverse to the weld run. The specimens were subjected to metallographic examinations and hardness measurements. Additionally, the joint cross-section was examined by destructive testing methods to enable precise determination of the internal defects and imperfections. The surface methods were applied again, this time to determine the severity of welding defects. The analysis has proved that, fabricated under proper conditions and with parameters of the welding process duly observed, the welded joint has good properties and repairs of this type are possible in practice.