During galvanized metal products processing, various defects often occur due to various factors. These defects not only affect the aesthetics of the product, but may also reduce its corrosion resistance and service life. The following are some common galvanizing defects and their preventive measures.
Skipping is one of the common defects in the galvanizing process, which is manifested as the metal surface is not completely covered with zinc layer, resulting in exposure of the substrate. This is usually caused by incomplete pre-treatment, insufficient zinc liquid temperature or contaminants on the strip surface. Preventive measures include strengthening the pre-treatment process to ensure that the metal surface is clean and oil-free; increasing the zinc liquid temperature to reach the ideal galvanizing temperature; at the same time, optimizing process parameters such as air knife angle and pressure to reduce splashing and waste of zinc liquid.
Zinc nodules are another common galvanizing defect, which is manifested as uneven zinc blocks or zinc nodules on the metal surface. This is usually caused by excessively high zinc liquid temperature, excessive strip speed or improper air knife adjustment. In order to prevent the formation of zinc nodules, it is necessary to strictly control the temperature of the zinc liquid to avoid it being too high; adjust the strip speed to match the temperature of the zinc liquid; at the same time, reasonably adjust the angle and pressure of the air knife to ensure that the zinc liquid can evenly adhere to the metal surface.
In addition, hydrogen embrittlement is also a problem that needs to be paid attention to during the galvanizing process. Hydrogen embrittlement is caused by the metal absorbing too much hydrogen during the galvanizing process, which causes microcracks inside the metal, thereby reducing its mechanical properties. In order to prevent hydrogen embrittlement, it is necessary to ensure that the hydrogen content in the galvanizing liquid is moderate and avoid being too high; at the same time, appropriate heat treatment should be carried out after galvanizing to eliminate the residual stress inside the metal.
In short, there are many kinds of defects in galvanized metal products processing, but these defects can be effectively prevented by strengthening pre-treatment, strictly controlling process parameters and optimizing galvanizing equipment. At the same time, regular inspection and maintenance of galvanizing equipment to ensure that it is in good working condition is also an important way to improve the quality of galvanized metal products.
