Liquid metal embrittlement sensitivity of the T91 steel in lead, in bismuth and in lead-bismuth eutectic

Abstract : The liquid metal embrittlement (LME) sensitivity of the martensitic T91 steel by Pb, Bi and LBE has been studied by small punch tests at different temperatures and strain rates. The LME occurrence in the three liquid metals depends on the strain rate and on the temperature. The T91 steel loaded in Bi, Pb or LBE presents ductile behaviour at 300 C and at 400 C except in LBE at 300 C at very slow strain rate for which fully brittle fracture surface was observed. It appears that the LME sensitivity of the T91 steel by LBE and bismuth is more important at 300 C than 400 C. No LME by lead has been observed. The most embrittling liquid metal is LBE, then bismuth while the less one is lead. Some differences in the reactive wetting of the T91 steel by the saturated oxygen liquid metal could explain the difference in LME sensitivity in the three liquid metals.