[ALUMINIUM NETWORK] Aluminum alloys are prone to oxidation and gas absorption during the smelting process, as they come into direct contact with furnace gases or the surrounding atmosphere. If the control during this phase is not precise, the alloy can easily absorb gases, leading to the formation of pores. Among these, pinholes are the most common type—tiny voids less than 1 mm in diameter that appear as round cavities scattered throughout the casting. These pores are typically unevenly distributed, especially in thick sections where the cooling rate is slower. Based on their distribution and shape, pinholes in aluminum alloys can be categorized into three main types. 1. Mesh Pinholes: These appear as a dense network of small holes within the microstructure. They often contain a few larger voids, making it difficult to count them per unit area or accurately measure their size. This type is usually more challenging to analyze under low magnification. 2. Dot-shaped Pinholes: In low-power microstructures, these pinholes appear as clearly defined, circular voids that are spaced apart. Their number per square centimeter can be counted, and their diameters can be measured. This makes them easier to distinguish from other defects such as shrinkage cavities or shrinkage porosity. 3. Composite Pores: These represent an intermediate form between mesh and dot-shaped pinholes. Under low magnification, they appear as numerous large voids, but unlike the round shape of dot-shaped pinholes, they tend to be polygonal in form. Practical experience in aluminum alloy production has shown that hydrogen is the primary gas absorbed during the melting process, and its behavior doesn't follow a predictable pattern. It's common for almost all castings to exhibit some degree of pinholing, and no specific alloy composition is completely immune to this issue. Understanding the nature and causes of pinholes is essential for improving the quality and performance of aluminum castings. Double Glazed Laminated Glass,Building Laminated Glass,Tempered Laminated Glass,Low Iron Building Industrial Glass SHANDONG TOP LEADER GLASS CO.,LTD , https://www.topleaderglass.com