Liquid metal embrittlement susceptibility of ferritic–martensitic steel in liquid lead alloys

Abstract

The susceptibility of the ferritic-martensitic steels T91 and EUROFER97 to liquid metal embrittlement (LME) in lead alloys has been examined under various conditions. T91, which is currently the most promising candidate material for the high temperature components of the future accelerator driven system (ADS) was tested in liquid lead bismuth eutectic (LBE), whereas the reduced activation steel, EUROFER97 which is under consideration to be the structural steel for fusion reactors was tested in liquid lead lithium eutectic. These steels, similar in microstructure and mechanical properties in the unirradiated condition were tested for their susceptibility to LME as function of temperature (150-450°C) and strain rate (1 Â 10 À3 -1 Â 10 À6 s À1 ). Also, the influence of pre-exposure and surface stress concentrators was evaluated for both steels in, respectively, liquid PbBi and PbLi environment. To assess the LME effect, results of the tests in liquid metal environment are compared with tests in air or inert gas environment. Although both unirradiated and irradiated smooth ferritic-martensitic steels do not show any or little deterioration of mechanical properties in liquid lead alloy environment compared to their mechanical properties in gas as function of temperature and strain rate, pre-exposure or the presence of surface stress concentrators does lead to a significant decrease in total elongation for certain test conditions depending on the type of liquid metal environment. The results are discussed in terms of wetting enhanced by liquid metal corrosion or crack initiation processes.

Compatibility of martensitic/austenitic steel welds with liquid lead bismuth eutectic environment

“…The sample inside the 316L weld deposit did however suffer from liquid metal embrittlement since its total elongation is significantly reduced. This effect is comparable with the embrittlement found in ferritic/martensitic steels after exposure in lead alloys with low oxygen contents [10,11] and does not represent a dramatic problem since sufficient ductility is still present. The sample with the HAZ on the T91 side in the middle of the gauge however, broke in a very brittle manner displaying very little elongation and no necking at all.…”

Effects of temperature and strain rate on the tensile behaviors of SIMP steel in static lead bismuth eutectic

“…The mechanical properties of steels deteriorate when stressed in liquid metal environment [12][13][14]. Literature [10,15] shows that the total elongation, strength, fracture energy, creep-rupture, ductility, fatigue life of structural materials are deteriorated by LBE.…”

Fatigue Life Prediction for Steels in Pulsating Irradiated Systems

“…All of these failure modes may be encountered in the pulsating irradiated system under consideration due to the possible use of liquid metals or molten salts as coolants, as well as the presence of hydrogen isotopes, including deuterium and tritium, at significant concentrations. Liquid metal embrittlement (LME) of ferritic-martensitic (FM) steels in molten lead alloys, including EUROFER97 and T91, had been studies at 150-450 at strain rates from 110 -3 to 110 -6 s -1 , are discussed in the literature [Van den Bosch et al 2008]. While there was relatively little sensitivity to the liquid metals in very smooth samples, samples with stress concentrators in the surface (notched specimens), and samples that had already been exposed and corroded by these liquid metals exhibited a substantial decrease in the total elongation at failure.…”