An Overview of the Material Processes for Superlloy Forgings

The development of high-temperature alloy forging technology has made significant contributions to the aerospace, power generation, petrochemical, and other industries. High-temperature alloy forging has become an essential method for producing critical components with excellent mechanical properties at high temperatures.

High-temperature alloy forging materials mainly use nickel-based alloys, such as Inconel 718, Waspaloy, and Rene 41, as well as cobalt-based alloys, such as Haynes 188, and ATI 718Plus. These materials have excellent mechanical properties, corrosion resistance, and thermal stability at elevated temperatures, making them widely used in various applications.

The forging process, which is a plastic deformation process, can alter the microstructure of high-temperature alloys, and thus influence their mechanical properties. The forging process is usually divided into several stages, including pre-forging, precision forging, and heat treatment. The pre-forging stage aims to reduce the forging load and eliminate defects in the billet. The precision forging stage is the primary forming stage and requires high-precision control of the deformation parameters. Heat treatment aims to homogenize the microstructure and improve the mechanical properties of the forged product.

Forging temperature is one of the critical factors affecting the microstructure and mechanical properties of high-temperature alloy forgings. The forging temperature is related to the different deformation mechanisms. In general, lower forging temperatures can form fine-grained microstructures, which can enhance the strength and reduce the deformation resistance. However, too low forging temperature can cause cracking, and too high forging temperature can lead to grain growth and reduced mechanical properties.

In addition to the forging process, the post-forging processing of high-temperature alloy forgings is also critical. Surface treatment, such as shot peening and surface polishing, can improve fatigue resistance. Coating technology, such as thermal barrier coatings and corrosion-resistant coatings, can improve the material's properties in harsh environments.

Moreover, there are different forging methods for high-temperature alloys, including hydraulic forging, screw forging, and isothermal forging. Each method has its advantages and limitations. Hydraulic forging is the most widely used method because it is simple, efficient, and economical. Screw forging can produce complex-shaped parts with high precision. Isothermal forging can eliminate residual stress and improve material properties.

In conclusion, the development of high-temperature alloy forging technology has played a critical role in various industries. The materials, forging process, and post-forging processing play an essential role in producing high-quality forged products. High-temperature alloy forging technology will continue to develop, and new materials and forging methods will emerge, leading to more exciting applications.