The liquid metal embrittlement of iron and ferritic steels in sodium

Abstract The liquid metal embrittlement of iron and A508 III, 2 1 4 Cr-1Mo and 15Mo3 steels in sodium at 200–400 °C has been studied, using dynamic straining at 10 −6 s −1 , in order to investigate the roles of microstructure and composition. The steels comprised bainitic, martensitic, tempered martensitic and ferritic/pearlitic microstructures. All materials were embrittled by sodium, the embrittlement being associated generally with quasicleavage on fracture surfaces. Intergranular cracking was also found with martensitic and ferritic/pearlitic microstructures. The susceptibility to embrittlement was greater in higher strength materials and at higher temperatures. The embrittlement was similar to that encountered previously in 9Cr steel, which depends upon the presence of non-metallic impurities in the sodium.