Effects of solutioning and ageing treatments on properties of Inconel-713C nickel-based superalloy under creep loading

As nickel-based superalloys have been widely used in turbine blades of turbo-chargers in automobile industries, this article has presented the creep behavior of the Inconel-713C nickel-based superalloy. For this objective, forced-controlled creep testing has been performed at the temperature of 850 °C and under the stress of 585.5 MPa. Then, the effect of the solutioning process on creep (time-dependent) properties of the superalloy was investigated. Optical and scanning electron microscopies were utilized to study the material microstructure, before and after creep testing. The X-ray diffraction (XRD) spectrometry was also used to detect different phases in the superalloy. Results showed that solutioning at 1200 °C for 1 h had a lowering effect on the creep rupture time of the Inconel-713C superalloy, as the mean size of the γ′ particles crystallite was about 6.8 nm. When the superalloy was aged for 16 h at 930 °C, an insignificant effect with respect to the as-cast sample could be observed, due to the precipitation of NbC carbides (at grain boundaries) and the coarsening behavior of γ′ particles. Consequently, different microstructures led to different creep fracture mechanisms for this alloy. The decomposition of MC carbides to M23C6 was also observed for all samples after creep testing.