The moisture in the arc column atmosphere, the moisture absorbed by the welding material and the oxide film on the surface of the base metal are all important sources of hydrogen in the weld. High-temperature aluminum has very low strength, difficult to support the molten pool, and easy to weld through. During the welding process, a large amount of heat can be quickly transferred to the inside of the base metal. There is no obvious color change when the solid and liquid transition states, and it is difficult to judge during welding operations.

In tungsten argon arc welding, AC power is used to remove the oxide film through 'cathodic cleaning'. For example, the helium arc has a large heat, and the helium or argon-helium mixed gas is used for protection, or the large-scale molten electrode gas shielded welding is used. It hinders the melting and fusion of the base material, and the oxide film has a large specificity, which is not easy to surface, and it is easy to generate defects such as slag inclusion, lack of fusion, and incomplete penetration.

According to production experience, when the silicon content is 5% to 6%, thermal cracking will not occur, so the use of SAlSi (silicon content 4. The resulting aluminum oxide (Al2O3) has a high melting point and is very stable, making it difficult to remove. If the base metal of the base metal is deformation strengthening or solid solution aging strengthening, welding heat will reduce the strength of the heat-affected zone. When the silicon content of aluminum-silicon alloy is 0. When the aluminum welding molten pool is solidified, shrinkage cavities, shrinkage porosity, thermal cracks and high internal stress are prone to occur.

Therefore, measures must be taken to prevent welding deformation.Aluminum is a face-centered cubic crystal lattice without allotropes, and there is no phase change during heating and cooling. The weld grain is easy to be coarse, and the grain cannot be refined by phase change.5% to 6%) welding wire will have better crack resistance. China High pressure casting Aluminum has a strong ability to reflect light and heat.5%, the hot cracking tendency is greater. Therefore, the source of hydrogen must be strictly controlled to prevent the formation of pores. When welding thick plates, the welding heat can be increased. 　　

Alloy elements are easy to evaporate and burn, which reduces the weld performance. Where the corrosion resistance permits, aluminum-silicon alloy welding wire can be used to weld aluminum alloys other than aluminum-magnesium alloys. In the case of direct current connection, the 'cathode' is not required Clean up'. The thermal conductivity of aluminum is ten times that of austenitic stainless steel. In the process of solidification and rapid cooling of the weld pool, hydrogen is too late to overflow, and hydrogen pores are easily formed. 

Megosztás a facebookon