Defects and Countermeasures for Large Forgings
Large forgings are used extensively in many industrial applications, such as the construction of pressurized piping systems, automotive components, large gears and valve bodies, and other heavy loads. However, due to its complex structure, large forgings often contain defects that can dramatically reduce their structural integrity and reliability. Generally, the most common defect of large forgings is the occurrence of air bubbles. This article explores the origins, manifestations and countermeasures of air bubbles in large forgings.
Firstly, air bubbles occur in large forgings due to gasification defects in molten metal. This defect occurs when gas infiltration occurs during the solidification process of the forging, creating a large number of gas pathways in the metal, resulting in the incomplete filling of the forging cavity. In addition, extreme temperatures and temperature gradients during the forging or casting process can also cause air bubbles to occur.
Air bubbles manifest in a variety of ways in a large forging. Severe air bubbles can cause extremely porous structures, with small pores scattered throughout the structure. This can lead to significant corrosion, mechanical damage, and a decrease in the strength of the part. In some cases, air bubbles can affect the surface finish of the part, resulting in a weak and blemished surface.
To prevent the appearance of air bubbles in large forgings, several countermeasures must be taken. Firstly, the molten metal used in the forging process should be closely monitored and its composition carefully determined, as any gas infiltration can cause air bubbles to form. Furthermore, heat treatment during the forging process should be closely monitored, as extreme temperatures and temperature gradients can also induce air bubbles. Finally, modification and adjustment of the casting machines and moulds used to create the forging can help ensure a uniform and smooth process.
In conclusion, air bubbles are one of the most common defects in large forgings. This defect can drastically reduce the structural integrity and reliability of the forging, and must thus be avoided. Although air bubbles are difficult to prevent, precise monitoring of the molten metal, heat treatment and machine moulds used in the forging process are essential for ensuring an air bubble-free forging.
