Because welding deformation is mostly caused by asymmetric heat generated by welding, the expansion is different. Several methods to prevent welding deformation are arranged as follows for reference:
Reduce the cross-sectional area of weld, and try to use smaller groove size (angle and gap) on the premise of not exceeding the standard defects.
Thick plate welding should be replaced by multi-layer welding as far as possible.
Under the condition of meeting the design requirements, the longitudinal stiffener and the transverse stiffener can be welded by intermittent welding.
When two sides can be welded, double-sided symmetrical grooves should be adopted, and neutral and symmetrical welding sequence should be adopted for multi-layer welding.
When the thickness of the T-joint is large, the butt weld should be completed by chamfering the corner.
Reverse deformation before welding is used to control angular deformation after welding.
The rigid fixture is used to control the post-welding deformation.
The longitudinal shrinkage deformation of weld is compensated by the method of reserved length of components. For example, 0.5~0.7 mm can be reserved for each meter of H-shaped longitudinal weld.
For the distortion of long members. Mainly by improving the flatness of the plate and the assembly accuracy of the parts, the groove angle and gap are accurate. Accurately align the arc or center, so that the angular deformation of the weld and the longitudinal deformation of the wing plate and web plate are consistent with the length direction of the component.
When assembling components or installation structures with more welding seams, a reasonable welding sequence should be adopted.
When welding thin plates, underwater welding method is adopted. That is, the molten pool is surrounded by the protective gas in the water, and the nearby water is completely eliminated by the gas to ensure the normal welding. By this method, the metal around the solid bath is cooled by water in time, and the deformation is controlled in a small range (circulating cooling liquid is added opposite the welding side to take away the heat generated by welding).
Multi-section symmetrical welding, that is, welding one section, stopping for a while, opposite welding, stopping for a while.