How to control welding deformation and stress in steel structure welding process？

In the steel structure welding process, it is very important to control welding deformation and stress, which can be achieved through the following measures:

Choose a reasonable welding sequence: When welding, a reasonable welding sequence should be selected based on the shape of the component and the welding arrangement. For example, for assembly conditions with many welds, the principle of welding the welds with larger shrinkage first and welding the welds with smaller shrinkage last should be adopted. This can effectively control the generation of welding deformation and stress.

Adopt the anti-deformation method: before welding, the component is deformed in the opposite direction to the welding deformation to offset the deformation after welding. This method requires predicting the direction and size of welding deformation in advance and taking corresponding measures to reverse the deformation.

Rigid fixing method: For some components that are prone to deformation, rigid fixing can be used before or during the welding process to limit their deformation. For example, clamps or temporary supports may be used to secure the member until the welding is completed and cooled before removal.

Preheating and postheating: For some thicker or more rigid components, preheating can be used before welding to reduce the temperature gradient during welding and reduce the generation of welding stress. After welding is completed, post-heat treatment can also be performed to further eliminate welding stress.

Reasonable welding process parameters: Selecting reasonable welding process parameters, such as welding current, voltage, welding speed, etc., can effectively control the generation of welding deformation and stress. Excessively large welding parameters may easily lead to an increase in welding deformation and stress, while too small welding parameters may lead to a decrease in welding quality.

Hammering method: Immediately after each layer of weld bead is welded, use a round-head slag hammer or electric hammering tool to evenly hit the weld metal to cause plastic extension deformation of the weld metal and offset the stress experienced by the weld after cooling. local tensile stress. However, it should be noted that the root weld, the weld bead at the groove edge and the cover weld bead should not be hammered to avoid welding defects such as undercutting caused by the hammering and extrusion of the weld bead edge.

To sum up, controlling welding deformation and stress requires starting from many aspects, including selecting a reasonable welding sequence, using anti-deformation method, rigid fixation method, preheating and postheating, reasonable welding process parameters, and hammering method. In actual operations, appropriate measures should be selected according to specific conditions to ensure welding quality and safety.