Causes and preventive measures of local deformation in welding

- Nov 24, 2020-

1.1 Cause


    The rigidity of the processed part is small or uneven, and the shrinkage after welding is inconsistent with inconsistent denaturation; the uneven layout of the welded seam of the processed part itself causes uneven shrinkage, and the parts with many welds have large shrinkage and large deformation; improper operation by processing personnel and unsymmetrical division Layer, segment, and intermittent welding, welding current, speed, and direction are inconsistent, resulting in inconsistent deformation of processed parts; excessive bite during welding will cause welding stress concentration and excessive deformation; welding placement is uneven, and deformation will occur when the stress concentration is released.

1.2 Preventive measures

    When designing, try to make the stiffness and welding seams of each part of the workpiece evenly arranged, symmetrically set the welding seams to reduce cross and dense welding seams; formulate a reasonable welding sequence to reduce deformation. For example, if the main weld is welded first and then the secondary weld, the symmetrical weld is welded first and then the asymmetric weld is welded, the weld with large shrinkage is welded first, and then the weld with small shrinkage is welded, and the butt weld is welded first. Fillet welds; For workpieces with large welds and many welds, use segmented, layered, and intermittent welding, and control the current, speed, and direction to be consistent; when manually welding long welds, use segmented intermittent welding , Welding from the middle of the workpiece to both ends, the personnel should be arranged symmetrically and dispersedly during welding to avoid deformation due to heat concentration; if the shape of a large workpiece is asymmetric, the small parts should be assembled and welded after the deformation is corrected, to reduce Overall deformation; the workpiece should be turned frequently during welding to offset each other; for parts that are prone to angular deformation after welding, pre-deformation treatment should be carried out before welding, such as steel v-shaped groove butt joints, and the joints should be properly adjusted before welding The pad is high, so that it can be flattened after welding; the external welding reinforcement is used to increase the rigidity of the workpiece to limit the welding deformation. The location of the reinforcement should be set on the opposite side of the shrinkage stress.