Formation and Dissolution of γ’ Precipitates in IN792 Superalloy at Elevated Temperatures

Abstract

Precipitation of γ' phase in nickel-base superalloy IN792-5A was studied using in-situ Small Angle Neutron Scattering (SANS). It was found that additional precipitates are formed after reheating above 600˝C when the material is previously fast cooled (100 K/min) from 900˝C. The size distribution and volume fraction of the additional γ' precipitates as well as of the already present medium-size precipitates in dependence on temperature were evaluated. The small precipitates can influence mechanical properties of the alloy, which exhibits an anomaly in the temperature dependence of the yield stress. Volume fraction of all precipitate populations above 900˝C was estimated as well.

Electron Beam Welding of IN792 DS: Effects of Pass Speed and PWHT on Microstructure and Hardness

“…In fact, the present results confirmed observations by other investigators [ 40 , 41 ], namely the precipitation of small particles of secondary γ’ from 600 to 875 °C determining an increase of IN792 yield stress and hardness. The phenomenon has been very carefully investigated by Strunz et al [ 42 ] through Small Angle Neutron Scattering (SANS) measurements.…”

“…As discussed before, the increase of hardness depended on the precipitation of secondary γ’ phase, due to the temperatures of PWHTs. In Strunz et al [ 42 ] it was reported that the precipitation of secondary γ’ in IN792 is maximum at about 725 °C, determining a significant increase of yield stress.…”

Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM

“…After several decades, the archetype of the superalloys, two-component Nichrome, was modified to such an extent that the alloying elements exceeded twelve. The best examples of this are the microstructurally complex superalloys as MAR-M247 and Inconel 792+Hf [ 33 , 34 , 35 ].…”

Characterization of γ′ Precipitates in Cast Ni-Based Superalloy and Their Behaviour at High-Homologous Temperatures Studied by TEM and in Situ XRD

“…So, the misfit measured for the standard heat treatment condition (solution + ageing), with a fully coherent γ phase, is not the equilibrium value, but a constrained value for the superalloy [23][24][25]. The start temperature of γ dissolution (T sd ) for Inconel 738, determined by Zla [26] by differential thermal analysis, was reported to be between 914 and 957 • C, depending on the heating rate, and for Inconel 792, Strunz [27] showed T sd to be below 900 • C. In PM Astroloy, the start of dissolution occurred between 800 and 850 • C [28]. Sponseller [29] calculated γ solvus temperature (T s ) for some superalloys to be between 1189 • C (equiaxed René 95) and 1307 • C (CMSX-2), and so the interval was also relatively wide.…”