Effects of liquid metal embrittlement on an alumina forming martensitic steel

Abstract

Liquid metal embrittlement was observed in an alumina-forming martensitic (AFM) steel tested in both liquid Pb and lead–bismuth eutectic (LBE) in the temperature range 350–550 °C and 150–550 °C, respectively, using slow strain rate testing (SSRT) in a low oxygen environment (∼10^-11 wt% O dissolved in Pb). A significant decrease in the total elongation to failure (TEF) could be observed in both environments, with LBE yielding the lowest measured TEF of 0.9 % strain at 150 °C. The elongation to failure followed the classic pattern of a ductility dip, gradually recovering with increasing testing temperature so that fully ductile behaviour was restored at 550 °C. There may be a potential to improve the performance of the AFM alloy by optimizing the microstructure through adjustments to the austenitizing, quenching and tempering conditions.