Influence of welding residual stress

1. Influence on the static strength of the structure: for the material with certain plasticity, the welding residual stress has no influence on the structural strength under the static load;

2. Influence on stiffness: welding residual stress will reduce the stiffness of the structure;

3. The influence of welding residual stress on the stability of compression bar: welding residual stress will reduce the bending stiffness and the stable bearing capacity of compression bar;

4. Influence on low temperature cold brittleness: thick plate and triaxial cross weld will produce triaxial welding residual stress, hinder plastic deformation, make cracks easy to produce and develop at low temperature, accelerate the brittle failure of components;

5. Effect on fatigue: welding residual stress has a negative effect on fatigue strength, resulting in higher residual tensile stress in and around the weld.

Methods of reducing welding residual stress and welding deformation

1. Adopt reasonable welding sequence: for example, steel plate butt welding adopts segmented back welding, thick welding adopts layered welding, I-beam adopts oblique jump welding, etc;

2. Before welding, the component is pre deformed contrary to the welding deformation, so that the welding deformation after welding is just offset;

3. For small size weldments, preheat before welding or temper after welding (heated to 600 ℃) ° Slow cooling can eliminate welding residual stress. Welding deformation can also be eliminated by mechanical method or oxyacetylene flame.