來源：http://www.leblogdejc.com/ 發布時間：2021-09-13 瀏覽次數：
The basic forms of welding deformation include shrinkage deformation, angular deformation, bending deformation, wave deformation and distortion deformation. Uneven heating and cooling of weldments during welding is the root cause of welding stress and deformation. The process measures to reduce welding stress and deformation mainly include:
1、 Reserved shrinkage deformation according to theoretical calculation and practical experience, shrinkage allowance shall be considered in advance during material preparation and processing of weldments, so that the workpiece can reach the required shape and size after welding.
2、 According to theoretical calculation and practical experience, the inverse deformation method estimates the direction and size of structural welding deformation in advance, and then gives a preset deformation with opposite direction and equal size during welding assembly to offset the deformation after welding.
3、 When welding with rigid fixation method, the weldment shall be rigidly fixed. After welding, the rigid fixation shall be removed after the weldment is cooled to room temperature, which can effectively prevent angular deformation and wave deformation. This method will increase the welding stress and is only suitable for low carbon steel structures with good plasticity.
4、 Select a reasonable welding sequence to make the weld shrink freely as much as possible. When welding structural parts with many welds, the staggered short welds shall be welded first, and then the straight long welds shall be welded to prevent cracks at the joint of welds. If the weld is long, the step-by-step back welding method and skip welding method can be used to make the temperature distribution more uniform, so as to reduce the welding stress and deformation.
5、 Hammering weld method in the cooling process of the weld, use a small round head hammer to hammer the weld evenly and quickly, so as to make the metal produce plastic extension deformation and offset part of the welding shrinkage deformation, so as to reduce the welding stress and deformation.
6、 Before welding by heating the "stress relief zone" method, heat the area near the welding part (called the stress relief zone) to make it elongate. When cooling after welding, the heating zone shrinks together with the weld, which can effectively reduce the welding stress and deformation.
7、 The purpose of preheating before welding and slow cooling and preheating after welding is to reduce the temperature difference between the weld area and other parts of the weldment, reduce the cooling rate of the weld area, so that the weldment can be cooled evenly, so as to reduce welding stress and deformation.