Basic welding deformation type. "Welding deformation" refers to the deformation caused by the high temperature of welding arc in the welding process of steel structure engineering, as well as the residual deformation phenomenon of component after welding. Among them, welding residual deformation is the main factor affecting welding quality, and it is also the most destructive kind of deformation.
Residual deformation in the welding process can be divided into integral deformation and local deformation. According to the different characteristics of deformation, it can be divided into corner deformation, bending deformation, contraction deformation, distortion deformation, wave deformation and staggered deformation. Among them, angular deformation and waveform deformation become local deformation, other types of deformation are integral deformation, and the main form of steel structure engineering deformation is integral deformation.
The reason of weld deformation is analyzed. Rigidity of steel structure: rigidity is the ability of structure to resist tensile direction and bending deformation. The stiffness of steel structure mainly depends on the shape and size of section. For example, the amount of deformation of i-steel sections and longitudinal trusses depends mainly on the part of the cross-sectional area of the chord section size. In other cases, the amount of bending deformation of i-shaped, T-shaped or other shaped steel mainly depends on the bending stiffness of the section.
Weld position and number: when the steel structure stiffness is insufficient, in the design of welding joint position and number, should be arranged in a symmetrical way, and the welding order is reasonable, the member can only produce linear deformation, if the weld is asymmetrical layout, then more bending deformation. Welding method: thick steel plate welding, welding current is too large, welding rod diameter is too large, resulting in slow welding speed, resulting in welding deformation; When welding thick steel plate, the deformation caused by manual welding is smaller than that by automatic welding. When multi-layer welding is used, the weld shrinkage deformation of the first layer is the largest, the weld deformation of the second layer and the third layer is 20% of the first layer and 5%~10% of the second layer respectively.
The results show that there are more welding layers, and the welding deformation is obvious. The contraction deformation of discontinuous welding is smaller than that of continuous welding. The transverse contraction deformation of butt welding is 2-4 times larger than that of longitudinal contraction deformation. In order to prevent welding deformation, reasonable technological measures must be formulated during welding construction.
