Research Progress on Surface Impact Strengthening Mechanisms and Application of Nickel-Based Superalloys

There has been rapid development in the turbine power systems of aeroengines and gas turbines. Consequently, the application of surface impact strengthening technology for the surface strengthening of superalloys used in turbine rotors and its corresponding mechanisms have attracted wide attention. However, it is difficult to prevent the recovery and recrystallization of the surface hardened layer of superalloys serviced at high temperatures. This leads to the degradation of both the surface strengthening/toughening and fatigue resistance. This is the main hurdle restricting the wide application of surface impact strengthening technology for key components of advanced superalloys. In this paper, the progress made in surface impact strengthening mechanisms and the applications of nickel-based superalloys in recent years are summarized. The effect of surface impact strengthening on the surface strength, toughness, and fatigue resistance of nickel-based superalloys is analyzed. The evolution of the microstructure of the hardened surface of the alloys during long-term aging at high temperatures, and its effect on high-temperature stability are explored. The paper aims to provide essential and important information for developing surface impact strengthening mechanisms of nickel-based superalloys and improving the fatigue resistance of turbine rotors of aeroengines and gas turbines.