How to eliminate welding stress of steel plate?

1. Overall high temperature tempering (stress relief annealing)
Heat the whole welding structure to a certain temperature (depending on the metal material of the specific workpiece), keep it warm for a period of time, and then cool it. It can eliminate 80% - 90% residual stress. It is widely used as a stress relief process.

2. Local high temperature tempering only aims at the local tempering of the weld and its surrounding parts, and the effect of stress relief is not as good as that of overall tempering. The equipment is simple and suitable for the work pieces with simple structure and less constraint, such as long cylindrical vessels, pipe joints, butt joints of long components, etc.

3. Mechanical drawing method is used to load the welding workpiece, so that the welding compression plastic deformation area can be stretched, and the local compression deformation caused by welding can be reduced to reduce the stress. There are common hydrostatic test, the hydrostatic pressure is greater than the use pressure of the vessel, and the vessel is mechanically stretched at the same time of hydrostatic test. Eliminate the stress caused by partial welding.

4. Temperature difference tensile method (low temperature stress relief), one appropriate width on both sides of the weld shall be heated with oxyacetylene flame. Spray water for cooling at a certain distance behind the welding gun. The torch flame cooling spray moves at the same speed. Form a two temperature high (peak value about 200℃) welding area temperature low (about 100℃). Both sides of the metal due to thermal expansion of the lower temperature of the welding area for tensile plastic deformation. To offset the original compression plastic deformation. So as to eliminate the internal stress. It is commonly used in plate and shell structures with regular weld thickness less than 40 mm, and stress relief.

5. Vibration method, aiming at the weld area. The resonance between the source and the structure is stable. The plastic deformation in the weld area is caused by the variable load stress produced by stable resonance. To eliminate welding stress. It is better to use vibration method to eliminate stress of carbon steel and stainless steel metal structure. The device has the advantages of low price, simplicity, low processing cost and short time. Characteristics of oxidation problem without high temperature tempering.