Corrosion phenomena induced by liquid metals in Generation IV reactors

Investigation of crack propagation resistance of 304L, 316L and 316L(N) austenitic steels in liquid sodium

“…In mechanical testing experiments, one usually does not have the capability to wait for the required time to dissolve the native oxide even if the sodium chemistry is in the reducing range (typically [O]<3 wppm for nuclear reactor [2]) with the exception of creep testing which is a long-term mechanical test carried out in dedicated loops. With other types of mechanical testing, specimens need to be prepared in a pre-wetted state to allow reproducible crack initiation conditions followed by sodium supply at the crack tip by capillarity during the crack propagation phase.…”

“…Corrosion in liquid sodium is then mitigated via an active control of the oxygen concentration below a few wppm [1]. Carbon transport processes between structural materials or parts of sodium loops lead to carburization/decarburization issues [2]. Therefore, long term effects of exposure in loops have been predominantly studied in terms of material microstructure evolution and the subsequent mechanical properties degradation [3].…”

A Review of the Surface Modifications for Corrosion Mitigation of Steels in Lead and LBE

“…The corrosion phenomena have been very well described and summarized by Fazio and Balbaud in Ref. [17]. The corrosion mechanisms in LBE or lead depend on the chemical composition of the steel, the oxygen content in the liquid metal, and the temperature.…”

“…Cold-worked 316L are more sensitive to ferritization [31] and exhibit more severe dissolution corrosion [32] than solution-annealed 316L steels. The velocity of lead alloys impacts the corrosion rate of 316L steel which becomes much higher from a velocity of 2 m/s [17]. In low oxygen liquid metals, austenitic stainless steels corrode by selective dissolution of nickel in the liquid metal, which may result in the local transformation of austenite into ferrite in the depleted surface zones, as shown in Figure 3 [29].…”

“…Cold-worked 316L are more sensitive to ferritization [31] and exhibit more severe dissolution corrosion [32] than solution-annealed 316L steels. The velocity of lead alloys impacts the corrosion rate of 316L steel which becomes much higher from a velocity of 2 m/s [17]. For martensitic steels, homogeneous dissolution occurs promoting more (e.g., [18,33]) or less pronounced relief which may act further as a stress raiser, see Figure 4.…”