Corrosion behaviour of steels in lead-bismuth at 823 K

The corrosion behaviour of the martensitic T91 steel and the austenitic AISI 316L steel was analysed. The steels were immersed in stagnant molten Pb-55.2wt%Bi alloy at 823 K for different exposure times (t = 550-2000 h). The corrosion tests were carried out both under Ar and under Ar-5%H2 mixture. Under the oxidising conditions (PO2 = 6 x 10-3 Pa), the formation of oxide layers was observed which prevent the penetration of the liquid alloy into the matrix, while under the Ar-5%H2 mixture (PO2 = 3.2 x 10-23 Pa), two phenomena occurred: a 'reactive penetration' at the liquid alloy/steel interface and the competition between oxidation and penetration