Steel structure refers to the structure mainly composed of steel materials, which is one of the main types of building structures. The structure is mainly composed of steel beams, steel columns, steel trusses and other components made of section steel and steel plates. The components or parts are usually connected by welds, bolts or rivets. Because of its light weight and simple construction, it is widely used in large factory buildings, venues, special high-rise buildings and other fields.
In the welding process of steel structures, there are many matters that need to be paid attention to. If you neglect them, you may make a big mistake. The following are some matters needing attention:
1. Improper voltage selection during welding
During welding, the same arc voltage shall be selected regardless of the backing, filling, covering and groove size. In this way, the required penetration depth and width may not be reached, and defects such as undercut, air hole and splash may occur.
Solution: Generally, the corresponding long arc or short arc should be selected according to different situations to obtain better welding quality and work efficiency. For example, in order to obtain better penetration depth during backing welding, short arc operation should be adopted, and in order to obtain higher efficiency and penetration width during filling welding or capping welding, arc voltage can be appropriately increased.
2. Welding deformation is not controlled carefully
During welding, the deformation is not controlled from the aspects of welding sequence, personnel arrangement, groove form, welding specification selection and operation method, resulting in large deformation after welding, difficult correction and increased costs, especially for thick plates and large workpieces, which are difficult to correct and easy to cause cracks or lamellar tears by mechanical correction.
Solution: adopt reasonable welding sequence, select appropriate welding specifications and operation methods, and adopt anti deformation and rigid fixation measures.
3. Welding does not control welding current
During welding, in order to speed up the progress, the butt welds of medium and thick plates shall not be beveled. The strength index decreases, even fails to meet the standard requirements, and cracks appear during bending test, which will make the performance of the weld joint can not be guaranteed, and pose a potential hazard to the structural safety.
Solution: The welding current shall be controlled according to the welding current in the process qualification, and 10~15% floating is allowed. The blunt edge size of the groove should not exceed 6mm. When butt welding, when the plate thickness exceeds 6mm, the groove shall be cut for welding.
