Liquid metal embrittlement (LME) susceptibility of the 8–9% Cr martensitic steels F82H-mod., OPTIFER IVb and their simulated welded structures in liquid Pb–17Li

This paper describes the results of uniaxial tensile tests on two low activation steels F82H-mod. and OPTIFER IVb. The tests were performed under vacuum and in liquid Pb–17Li at temperatures of 250°C and 400°C at a constant displacement rate of 0.1 mm min−1, which corresponded to an initial strain rate of 1.1×10−4 s−1. Neither F82H-mod. nor OPTIFER IVb exhibited a liquid metal embrittlement (LME) susceptibility in the tempered fully martensitic state. However, tests of the heat affected zone (HAZ) specimens indicated an LME susceptibility for both steels tested at 250°C in Pb–17Li, while increasing the test temperature to 400°C led to the recovery in ductility. The effect of post-weld heat-treatment (PWHT) of the HAZ specimens of 750°C/1 h for F82H-mod. and 730°C/3 h for OPTIFER IVb was sufficient to regain the majority of their original mechanical properties.