Influencing Factors of Welding Deformation of Steel Grating

Release Time:

2021-11-09

1. Influence of input heat source on welding deformation

During the welding process of the steel grating, affected by the local high-temperature heat source, the weld zone is heated rapidly and locally melted. The material in this area is heated to expand the welded area, while the relatively low temperature area around the steel grid constrains the welded area, resulting in elastic thermal stress. The yield stress limit of the material drops sharply after the temperature rises, resulting in thermoelastic stress Exceeding the yield limit, thermal compression is formed.

During cooling, the shrinkage of the material in the weld zone is affected by the uneven temperature field in the surrounding area, resulting in uneven shrinkage deformation, the weld zone exhibits tensile residual stress, and the adjacent zone bears compressive residual stress. The welding of stainless steel grating is very sensitive to the input of heat source, and the reasonable control of the energy of the input heat source is of great significance to the quality of the grille weldment.
The input of larger heat source energy will cause larger shrinkage deformation, and conversely, the input of smaller heat source energy will cause smaller shrinkage deformation. Therefore, in the case of ensuring that the weld is well formed, the input heat source should be selected as small as possible.

2. Influence of weld size on welding deformation
For stainless steel grating welding, the area size of the weld is closely related to the deflection deformation of the steel grating weldment. In addition, the position of the weld in the structure will also have an impact on the welding deformation of the stainless steel grating. . The asymmetric arrangement will lead to the bending deformation of the weldment. The closer the neutral axis of the weldment section of the steel grating is to the weld, the smaller the bending deformation is; on the contrary, the farther the neutral axis of the weldment section is from the weld, the relatively The larger the bending deformation is.

3. Influence of initial roughness and plate thickness of welding plate on welding deformation

However, in actual processing and production, it is impossible to manufacture ideal stainless steel plates, which may have different degrees of initial deflection or initial geometric defects. These initial surface roughness and defects will cause the welding of steel gratings to a certain extent. Critical instability deformation.

For plates with unevenness problems, the increase of residual stress and the increase of plate deflection is relatively slow at the initial stage; but when the residual stress generated by welding exceeds a certain value, the instantaneous increase of plate deflection will be relatively fast. When the initial roughness is relatively large, the critical load value that the plate can bear will be reduced to a certain extent, and the instability deformation is easier to occur.

Therefore, the initial surface roughness of the stainless steel plate weldment must be strictly controlled, otherwise it will greatly affect the resistance to instability and deformation of the weld and the critical load. In addition to the initial surface roughness, the sheet thickness is also an important factor affecting the buckling deformation. The smaller the thickness of the welding plate, the smaller its stiffness and the lower its ability to resist bending deformation. When stainless steel plates are butt welded, they are more likely to be deflected and deformed under the influence of high-temperature heat sources. On the contrary, the greater the welding thickness, the greater the rigidity and less deformation.