AbstractIf loss of sound metal is taken into account as corrosion criterion, there is a factor of about 4 to 5 between austenitic and ferritic steels. As an examples, the loss of sound metal at 450°C is 100 μm·yr−1 for 316L steel and 22 μm·yr−1 for 1.4914 steel. This difference of behaviour seems to be slightly attenuated when temperature increases, owing to a higher activation energy of martensitic steel. The correspondence in term of temperature is of about 50°C.When corrosion criterion is mass transfer, the factor is reduced to about 2 between the two types of steel which corresponds in term of temperature to a difference of about 25°C between the two steels.