Tensile fracture behavior of notched 9Cr-1Mo ferritic-martensitic steel specimens in contact with liquid lead-bismuth eutectic at 350 °C

Cracking jumps were observed in notched T91 (9Cr-1Mo ferritic-martensitic steel) specimens tested in liquid lead-bismuth eutectic (LBE) at 350 °C under tensile loading. The cracking jumps manifested themselves as being regular steps at tensile curves, while as being fatigue striation-like markings at fracture surfaces. The markings were consisted of liquid metal embrittlement (LME) zones and ductile zones. The liquid LBE was adsorbed at crack tip and likely reduced the interatomic bonding strength, leading to cracking in a brittle way and release of elastic energy in the load line. This unique phenomenon was found to be associated with coupled effects of LME and compliance/stiffness of tensile machines.