Non-standard welding parts often produce welding deformation during the welding process due to uneven local heating and cooling. This deformation not only affects the dimensional accuracy and appearance quality of the welded parts, but may also reduce their mechanical properties and service life. Therefore, preventing and correcting the welding deformation of non-standard welding parts is an important part of the welding process.
The primary measure to prevent welding deformation is to reasonably design the weld structure and size. When designing the weld, unnecessary welds should be minimized, and welded parts should be replaced with steel sections and stampings to reduce the workload of welding and correcting deformation. At the same time, for thicker plate butt joints, it is recommended to use X-shaped grooves instead of V-shaped grooves to reduce the total amount of deposited metal and thus reduce welding deformation. On the basis of ensuring sufficient strength, a smaller weld size should be selected to avoid excessive weld cross-sectional area, which leads to an increase in plastic deformation caused by shrinkage during cooling.
The reverse deformation method is an effective method to prevent welding deformation. Before welding, the components are pre-assembled to have a deformation in the opposite direction to the expected welding deformation. This prefabricated deformation can be elastic, plastic, or elastoplastic, depending on the application scenario. The size of the reverse deformation needs to be precisely adjusted to fully offset the deformation after welding. Through the reverse deformation method, the deformation can be pre-compensated during the welding process, thereby reducing the degree of deformation after welding.
The rigid fixation method is a method of limiting welding deformation by increasing the rigidity of the structure. For structures with less rigidity, measures such as tire clamps or temporary supports can be used for fixation. This method can effectively reduce welding deformation, but it may also increase welding stress. Therefore, when using the rigid fixation method, it is necessary to weigh the relationship between deformation control and welding stress.
Selecting appropriate welding methods and parameters is crucial to preventing welding deformation. Using welding methods with higher energy density helps to reduce deformation. At the same time, by adjusting the welding heat input, using technical measures such as skip welding or gradual back welding, the welding temperature field can be further optimized to reduce deformation. In addition, selecting different welding parameters can also accurately control bending deformation.
Optimizing the assembly welding sequence is also an important means to prevent welding deformation. During the assembly process, the center of gravity position of the cross section will continue to change, which in turn affects the welding deformation. Therefore, simulation tests and analyses should be carried out for different components and important parts to determine the best assembly welding sequence. Through a reasonable assembly welding sequence, the stress and deformation during welding can be balanced, thereby reducing the degree of deformation after welding.
For non-standard welding parts that have already produced welding deformation, mechanical correction can be used for correction. The mechanical correction method is to apply force to the component through mechanical methods such as manual hammering or presses to make it produce new plastic deformation to offset the original deformation. This method is suitable for welded parts of various shapes and sizes, but attention should be paid to the strength and uniformity during the correction process to avoid new deformation or damage.
The flame correction method uses the local compression plastic deformation produced by flame heating to shorten the metal material after cooling, thereby achieving the purpose of eliminating deformation. The flame correction method is suitable for materials with good weldability such as low carbon steel and ordinary low alloy steel. When performing flame correction, the heating temperature and position need to be strictly controlled to avoid overheating or overburning that leads to a decrease in material performance. At the same time, attention should be paid to the cooling method after flame correction to avoid excessive residual stress and deformation.
The prevention and correction of welding deformation of non-standard welding parts requires multiple aspects such as design, process, assembly and correction. By rationally designing the weld structure and size, adopting the anti-deformation method, rigid fixation method, selecting appropriate welding methods and parameters, optimizing the assembly welding sequence, and adopting mechanical correction method and flame correction method, the degree of welding deformation can be effectively reduced and the quality and performance of welded parts can be improved.
