Microstructure Characteristics and Strengthening Mecha-nism of Ni-based Wrought Superalloy GH4350: A Review

Abstract:

GH4350 (AEREX 350) is a Ni-based wrought superalloy for high-performance fasteners, with a maximum service temperature of 750 °C. It has high tensile strength, fatigue resistance, stress rupture and relaxation resistance, corrosion resistance, low thermal expansion, and notch sensitivity. The high strength of GH4350 is largely derived through solid solution strengthening and the γ′ phase precipitation strengthening. During the precipitation of γ′ phase, a minor amount of η phase also precipitates. However, it is reported that the microstructure of alloy is sensitive to heat treatment parameters, including temperature and time. The γ′ phases can be transformed into η phases under certain conditions, potentially degrading the performance of the alloy. The chemical composition characteristics, heat treatment strategies, and strengthening mechanism of GH4350 were reviewed in this research, aiming to understand the factors behind its remarkable high-temperature performance, to guide the development of new alloys, and to further enhance its heat resistance.