The alloy will  have distortion after welding. Which increases the amount of repair after welding to a large extent and wastes a lot of working hours. In serious cases, the production schedule will be delayed. However, the catheter is the most critical component of the aircraft. It is large, complex, highly accurate, and requires minimal distortion. The overall distortion is not allowed to occur.Therefore, pay attention to the distortion research in the process of pipe welding. Improving the welding process through reasonable control measures, so as to improve the quality of pipe and meet the assembly requirements.

The cause of aluminum distortion alloy pipe welding

Because the thermal conductivity of aluminum is higher than that of ordinary materials. The structural control of aluminum alloy welding distortion is more difficult than that of other materials. The uneven heating in the welding process makes the temperature of the welding seam and its vicinity very high. After cooling, the welding seam produces different degrees of shrinkage and internal stress. Resulting in various distortion of the welding structure. The volume change caused by the change of grain structure in aluminum alloy may also cause welding distortion.  Which is the root cause of welding stress and distortion.

1) material: aluminum alloy has the characteristics of strong thermal conductivity and fast heat dissipation. The linear expansion coefficient is much larger than carbon steel, which causes the disrtortion in the welding process to be larger than carbon steel.

2) welding process parameters: welding current and welding speed directly affect the size of welding energy.Reasonable welding parameters can reduce welding distortion to a great extent.

3) assembly and welding sequence: in the assembly process of components, different welding sequence will produce different welding stresses. Therefore, different assembly and welding sequence will produce different disotortion amount for the same component. Assembly sequence is one of the key factors affecting distortion amount.

4) structural design: the structural design of the catheter product itself is complex, with many and long welds, improper position, inconvenient operation and other factors leading to large welding deformation.

The harmfulness of aluminum welding distortion and stress

The mechanism of internal stress during welding and the basic rule that determines the distortion of the workpiece after welding must be fully understood when manufacturing the welded structure of aluminum alloy.Distortion is much more harmful than residual stress. It makes the size of the welded parts change and cannot be assembled. It makes the whole component lose its stability and cannot bear the load.But correction will consume a lot of manpower and material resources, sometimes even lead to product scrap.At the same time, welding cracks are often closely related to residual deformation and stress.