Oxidation Behavior and Tensile Property of Inconel 617 in the Simulation Environment of the Very-High-Temperature Reactor

Abstract In this work, Inconel 617 was corroded at 950 °C up to 100 h in the impure helium and air atmospheres. The results show that the alloy oxidizes significantly more in air than impure helium, especially internally. There are two reasons for the difference in the oxidation of the alloy in the two atmospheres, one is the difference in the oxidizing gas content of the two, with air containing 21% O2 and only a small amount of H2O in the impure helium. The second is the occurrence of microclimatic reactions, which prompts the oxides that have been formed to occur reduction reaction. Differences in oxidation inevitably lead to differences in the tensile properties of the alloy. The results of the tensile tests shows that the yield strength (YS), ultimate tensile strength (UTS) and elongation (Elong) of Inconel 617 decreased from 309 MPa, 674 MPa, and 43.5% to 291 MPa, 649 MPa, and 39%, respectively, in the impure helium. In the air, the YS, UTS, and Elong of Inconel 617 were 299 MPa, 535 MPa, and 30%, respectively. One of the most important factors affecting degradation is oxidation, as elongated oxides (Al2O3) precipitating along the alloy grain boundaries can preferentially become the core of crack propagation and accelerate alloy failure. Therefore, to ensure the long-term safe operation of the reactor intermediate heat exchanger, the precipitation of excessive internal oxides from the alloy should be avoided as much as possible. controlling the CO content in helium is a simple and useful way to inhibit the oxidation of the alloy. A simple way to reduce the degree of oxidation of the alloy is to control CO in addition to minimizing the amount of oxygen and water in the helium.