Inconel 939

Overview of Inconel 939

IN939 is a class of advanced, high-temperature nickel-based alloys that modify the Waspaloy system [1]. It is a high-temperature alloy with a service temperature of up to 1123 K (850 °C). It is preferred for high-temperature service applications due to its superior creep strength, corrosion, and oxidation resistance owing to its composition [Table 1]. It has primarily been utilized in the form of cast alloy for the manufacturing of gas turbine blades/vanes as well as castings for turbines and burner nozzles, as seen from the prerequisites highlighted in Fig. 1. The strengthening mechanism of the alloy is due to the combination of the dendritic gamma solid solution matrix (γ) with a dispersion of gamma-prime precipitates (γ′) Fig. 2 (d), which enhance its mechanical properties [2,3]. The IN939 is typically produced as a solid cast and contains a large volume fraction of γ′ phase Fig. 2 (a), which can reach up to 30–40 % after heat treatment, and a γ-γ′ eutectic phase, which results from slower cooling, as can be seen in Fig. 2 (c). This is ratified by solution treatment of the part to create a super-saturated solid solution, which is then aged to produce γ’ strengthening phase [4].

Table 1. The general composition of IN939 alloy [20].