ã€China Aluminum Industry Network】When welding aluminum profiles, there are several key points that should be carefully considered to ensure a high-quality and durable weld. Here are seven important factors to keep in mind:
First, aluminum is highly prone to oxidation. In the air, it quickly forms a thin, dense layer of aluminum oxide (Al₂O₃), which has a melting point of around 2050°C—significantly higher than the melting point of aluminum itself (around 600°C). This oxide layer is hard to remove and can interfere with the welding process by preventing proper fusion between the base metals. It can also lead to defects such as porosity, slag inclusion, and lack of fusion, ultimately reducing the strength and performance of the weld.
Second, porosity is a common issue during the welding of aluminum and its alloys. This is mainly due to hydrogen, which dissolves easily in molten aluminum but not in solid aluminum. As the metal cools rapidly, the hydrogen gets trapped, forming bubbles within the weld. Even with high-purity argon gas (99.99% pure), if moisture levels exceed 20ppm, porosity can still occur. High humidity in the environment can further increase the risk of air holes in the weld.
Third, welding aluminum often leads to significant deformation and cracking. The coefficient of thermal expansion and contraction for aluminum is about twice that of steel, making it more susceptible to internal stress during cooling. This increases the likelihood of distortion, especially in rigid structures, and can contribute to hot cracking.
Fourth, aluminum has a much higher thermal conductivity than steel—approximately four times greater. This means that more heat is required during the welding process to achieve proper penetration, and the heat tends to dissipate quickly, making it harder to maintain consistent weld quality.
Fifth, alloying elements like magnesium, zinc, and manganese can evaporate under high-temperature arcs. This can alter the chemical composition of the weld metal, leading to reduced mechanical properties and potential failure in the long run.
Sixth, at high temperatures, aluminum exhibits low strength and plasticity, which can make it difficult to form a stable weld. In some cases, this can result in the weld metal sagging or even burning through the joint.
Finally, one of the most challenging aspects of welding aluminum is the absence of a visible color change when it transitions from solid to liquid. Unlike steel, which changes color as it heats up, aluminum remains gray throughout the process, making it harder for welders to accurately gauge the temperature and control the weld.
In summary, welding aluminum requires special techniques and careful attention to environmental conditions, material preparation, and equipment settings to overcome these unique challenges and produce strong, defect-free welds.
Hubei Chengze Diamod Products Co., Ltd. , https://www.ryomaltools.com