How to prevent aluminum alloy from expanding and deforming during welding?

【China Aluminum Network】
The melting state of the aluminum alloy in the molten state reduces its volume by approximately 6%, and the shrinkage stress generated during the process may cause deformation of the welded joint. The heat input from the welding will expand the metal in the vicinity of the weld zone. When the heat source leaves, the metal cooling will shrink. Together with the shrinkage of the molten metal in the cooling process, tensile stress will be generated at the weld and the crack sensitivity will increase. Excessive restrictions on the welding structure during cooling can also lead to welding cracks. The shape of the welding groove and the number of welds are the main factors affecting the deformation. The deformation of the double-sided butt welding is usually much smaller than that of the multi-weld V-groove welding. The welding speed is also the decisive factor in controlling the deformation. When the welding speed is low, the heat input will lead to more expansion and the shrinkage during cooling will also be larger. Insufficient heat input will result in poor melting of the weld, resulting in defects such as incomplete penetration and non-fusion. Preheating before welding can reduce the degree of deformation of the product and the tendency of cracks, and can increase the welding speed.