Defects and Countermeasures of Large Forgings
Large forgings are widely used in various fields such as industrial manufacturing, aerospace and military. Forgings produced with high performance, safety and reliability requirements have very high requirements for the accuracy of the forgings and require strict quality control. Improper control of the forging process will lead to various defects, resulting in the scrap of the forgings and the loss of superior performance. This article introduces some common defects in large forgings and their countermeasures.
Cracks: cracks are common defects in large forgings, mainly caused by severe changes in temperature during the forging process, as well as by excess pressure, high forging speed and improper forging material. In order to reduce the flaws caused by cracks, measures such as controlling the heating speed, improving the tempering process, using appropriate pre-forming and post-treatment and choosing the appropriate forging materials can be taken.
Folding: Folding defects can be caused by excessive forging pressure, excessive filling of casting, long flow distance from the die, unequal pressure conditions and the movement of the billet end. To prevent folding defects, refractory materials can be added to the side gates and flowing channels of the die for better liquid flow, the reinforcement ribs can be increased, the filling temperature and pressure can be reduced, the length of the flow channel can be shortened, and the size of the rollers and slide surfaces can be controlled.
Inclusions: foreign inclusions are caused by impurities introduced in the material, such as non-metallic impurities and oxide inclusions that have not been removed during smelting, or running-in, as well as too long forging-in time intervals. Therefore, in order to reduce foreign inclusions, the process parameters and forging materials must be properly selected to reduce the flowability of the metal, and the impurities should be removed as much as possible.
Size and shape: size or surface shape defects in large forgings are usually caused by uneven pressure, insufficient or excessive forging force, uneven temperature, improper die and filling parameters and poor alloy composition. Therefore, when producing large forgings, measures such as reducing the range and complexity of the sizes, controlling the pressure and temperature during the forming process, using high quality and appropriate forged materials, controlling the filling of the mould and adding reinforcement ribs to the mould can be taken to improve the quality of forgings.
The above are some of the most common defects in large forgings and their countermeasures. In order to ensure the high performance of large forgings, proper control of the forging process and use of qualified forging materials is necessary. This will not only reduce the loss caused by rejected forgings, but also guarantee the performance of large forgings.
