Étude du comportement structural de l'alliage NC 19 Fe Nb (Inconel 718)

Some features of anisothermal solid-state transformations in alloy 718

“…This peak is indicated with a double arrow on the bottom trace in Fig. 7; it is very similar to the peak observed by Slama and Cizeron with the same technique [16]. In many cases, a bounce of the DTA trace was observed when the signal reached the base line shortly after the cooling had started.…”

“…precipitation may occur during heating. Based on the previous analysis by Slama et al [16], the two exothermic peaks at 500 °C and 700 °C have been indexed as precipitation of γ′ and of γ″ respectively. As the temperature is further increased, a third exothermic peak at 850 °C and an endothermic peak above 1000 °C are observed.…”

High temperature deformation of Inconel 718

“…If this ratio goes up to 0.8, ␥ precipitation starts before than the ␥ one [3,4]. A typical precipitation time temperature (PTT) diagram [5] for this alloy is shown in Fig. 1.…”

In-Situ Determination of Precipitation Kinetics During Heat Treatment of Superalloy 718

“…[6] Because of the industrial importance of 718, a number of attempts have been made to quantify its aging response via the determination of both isothermal and continuous-cooling transformation diagrams. [7][8][9][10][11][12][13] A comparison of these measurements has revealed wide variations, some of which can be attributed to difficulties in resolving the fine strengthening phases and their volume fractions as well as the effect of relatively-small variations in alloying-element content (especially Nb), which are still within the nominal alloy specification, on overall phase equilibria. [14,15] For example, volume fractions reported in the literature for heat-treated 718 have varied from approximately 4 to 15 pct for c¢¢ and from 4 to 18 pct for and c¢.…”