Control and Correction of Welding Deformation of Welded Pipe and Thin Plate Structural Parts

During and after welding, the welding parts will deform. The thermal deformation during welding and the rigid condition of the parts to be welded are the basic factors affecting the deformation.

1、Factors affecting welding thermal deformation

1.Welding process

Different welding methods produce different temperature field and different thermal deformation. Automatic welding has narrow heating area, concentrated heating and small deformation.

2.Welding parameters

That is, arc voltage, welding current and welding speed. With the increase of welding current and arc voltage, the welding thermal deformation will also increase. With the increase of welding speed, the welding thermal deformation will decrease. The arc voltage has more obvious influence, so the automatic welding deformation of low voltage is smaller.

3.Construction method

When the temperature field of continuous welding and intermittent welding is different, the thermal deformation is also different. Generally, when the deformation of continuous welding is large, the deformation of intermittent welding is small.

4.Thermophysical properties of materials

Different materials have different expansion coefficient, thermal conductivity, thermal deformation and welding deformation.

2、Factors affecting welding stiffness coefficient

1.With the increase of rigidity, the deformation of the component is small.

2.Adopt tire clamp to increase rigidity of components and reduce deformation.

3.Assembly welding process will cause the change of rigidity and center of gravity in different assembly stages, which has a great influence on controlling the welding deformation of parts.

Generally speaking, in the case of less constraints, the welding deformation of the welded component is larger, on the contrary, the deformation is smaller.

Principle and method of controlling welding deformation of thin plate structure

There are two factors that affect the welding residual deformation: the thermal deformation in the welding process and the rigid condition of the welding component. According to these two factors, it can be considered that the welding residual deformation is inevitable, and it is necessary to take measures to control the welding residual deformation from the two aspects of sheet structure design and construction technology.

In addition to the strength and performance of the components, the design of thin plate structure should also meet the requirements of minimum welding deformation and minimum labor time consumption. The layout of plate joints in the design drawings is not considered carefully for the process, which is easy to cause welding deformation, so it is very important to optimize the layout of plate joints.

Welding process is one of the important processes in steel structure construction. Reasonable welding process is the method to reduce welding deformation and stress concentration.

To control the welding deformation, the component can be divided into several small parts, so that the welding deformation can be dispersed in each part, which is conducive to the control and correction of welding deformation. In order to avoid the post welding deformation and excessive bending deformation, the welding seam arrangement of the parts is symmetrical or close to the neutral axis of the component section, and the wide and long steel plate or the structural form that can reduce the number of welding seams are adopted.