Investigation of the abnormal effects of phosphorus on mechanical properties of INCONEL718 superalloy

The effects of phosphorus on mechanical properties of the world’s most widely used superalloy INCONEL718 was examined. The results indicate that P has little effect on the tensile properties of INCONEL718 at room temperature, 500 or 650°C, but it increases stress rupture life and ductility. Phosphorus also improves the creep property and crack propagation resistance of INCONEL718. Further microstructure analysis by means of optical, SEM and TEM does not reveal the obvious effect of P on grain size and precipitation of INCONEL718. Some theoretical discussions were held aiming at further understanding the role of P in INCONEL718. It was suggested that the interaction of P–GB–M (metal element) complex might be responsible for this.