The main causes are as follows:
1.The structure is unreasonable, the welding seam is concentrated and the welding joint stress is too large.
2.When welding, the molten pool is too large and overheated, and the alloy is burnt too much.
3.The arc crater is not filled due to too fast arc closing and too early wire drawing.
4.Material problems, for example, when Mg content is less than 3%, and impurities such as Fe and s exceed the standard, it is easy to cause cracks.
When the melting temperature of welding wire is too high, liquefaction cracks in heat affected zone are easy to occur.
Preventive measures include:
1.During the design, attention should be paid to the reasonable arrangement of welding seams, avoiding the stress concentration as far as possible, and selecting the welding sequence reasonably.
2.Reduce welding current or increase welding speed properly.
3.The arc stopping operation technology should be correct, and the arc pit should be filled by adding the outlet plate or using the current attenuation device.
4.Choose welding materials correctly.
