Welding Q355GNH weathering steel plate is to improve its welding performance on the basis of weathering steel. The reason why Q355GNH weathering steel plate is less used in building construction is not only the price factor, but also the poor welding performance. However, the appearance of welding Q355GNH weathering steel plate not only does not reduce the performance of weathering steel, but also improves its welding performance. In the later application, it reduces many troubles for the construction personnel. So how does the welding performance of Q355GNH weathering steel plate improve?
1. Choose basic low hydrogen electrode and flux. The basic low hydrogen electrode and flux welding joint have low hydrogen content, good desulfurization and dephosphorization performance and high impact toughness. Before use, it needs to be dried at 350c-420c for 1-2h, in order to effectively remove the moisture, so as to reduce the oxygen content of the welded joint and the cold cracking tendency of the joint.
2. The welding spare parts of Q355GNH weathering steel plate can only be assembled after passing the inspection. It is not allowed to assemble with strong force to avoid excessive assembly stress.
3. The parts to be welded on Q355GNH weathering steel plate and the range of 2mm for each of the two deletions shall be carefully cleaned to remove moisture, rust, oil and other impurities.
4. Arrange welding sequence of Q355GNH weathering steel plate reasonably. The principle is to make the majority of welds can be welded under the condition of small rigidity as far as possible, and further reduce the welding stress.
5. Preheat before welding, slow cooling after welding or heat treatment. Preheating before welding is usually an important technological measure to prevent cold crack in high strength steel welding. Slow cooling or heat treatment after welding can fully escape the diffusing hydrogen, reduce the welding residual stress, improve the structure of Q355GNH weathering steel plate, reduce the hardenability, and reduce the tendency of cold cracking.