Welding advantages of aluminum alloy casting


Posted May 10, 2022 by partscasting

For example, the heat of the helium arc is large, and it is protected by helium or argon-helium mixed gas, or by gas welding with a large-scale consumable electrode. In the case of a DC connection, "cathode cleaning" is not necessary.
 
Aluminum is easily oxidized in the air and during welding, and the resulting alumina, Al2O3, has a high melting point, is very stable, and is not easy to remove. It hinders the melting and fusion of the base metal, the proportion of the oxide film is large, it is difficult to surface, and defects such as slag inclusion, incomplete fusion, and incomplete penetration are easily generated. The oxide film on the aluminum surface and the adsorption of a large amount of water can easily lead to weld pores. Before welding, chemical or mechanical methods should be used for strict surface cleaning to remove the oxide film on the surface. Strengthen protection during welding to prevent oxidation. In TIG welding, the AC power source removes the oxide film by "cathode cleaning". In gas welding, a flux that removes the oxide film is used. When welding thick plates, the welding heat can be increased. For example, the heat of the helium arc is large, and it is protected by helium or argon-helium mixed gas, or by gas welding with a large-scale consumable electrode. In the case of a DC connection, "cathode cleaning" is not necessary.

2. The thermal conductivity and specific heat capacity of aluminum and aluminum alloys are about twice that of carbon steel and low alloy steel. The thermal conductivity of aluminum is more than ten times that of austenitic stainless steel. During the welding process, a large amount of heat can be quickly transferred to the inside of the base metal. Therefore, when welding aluminum and aluminum alloys, energy is dissipated not only in the molten metal pool, but also in other parts of the metal. This useless energy consumption is more significant than steel welding. In order to obtain high-quality welded joints, energy with concentrated energy and high power should be used as much as possible, and sometimes technological measures such as preheating can be taken.

3. The coefficient of linear expansion of aluminum and aluminum alloys is about twice that of carbon steel and low alloy steel. When aluminum solidifies, the volume shrinkage rate is large, and the deformation and stress of the weldment are large. Therefore, it is necessary to take measures to prevent welding deformation. The aluminum welding pool is prone to shrinkage, shrinkage, thermal cracks and high internal stress when it solidifies. Measures can be taken to adjust the composition of the welding wire and the welding process during production to prevent the occurrence of hot cracks. Under corrosion-resistant conditions, in addition to aluminum-magnesium alloys, aluminum alloy wires can be used to weld aluminum alloys. When the silicon content in the Al-Si alloy is 0.5%, the hot cracking tendency is relatively large. With the increase of silicon content, the crystallization temperature range of the alloy becomes smaller, the fluidity increases significantly, the shrinkage rate decreases, and the hot cracking tendency decreases accordingly. According to production experience, when the silicon content is 5% to 6%, thermal cracking will not occur, so the wire containing SAlSi with a silicon content of 4.5% to 6% has better crack resistance.

4. Aluminum has a strong ability to reflect light and heat, and there is no obvious color change when solid and liquid changes, so it is difficult to judge during welding operations. High temperature aluminum has low strength, it is difficult to support the molten pool, and it is easy to weld through.

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Issued By Casting
Country Aruba
Categories Accounting , Advertising , Aerospace
Tags alloy belt pulley , aluminum alloy die casting , casting parts
Last Updated May 10, 2022