Effect of water vapour on the oxidation of Fe–13Cr–5Ni martensitic alloy at 973 K

Effect of water vapour on oxidation of Fe–13Cr–5Ni martensitic alloy at 973 K was investigated. Water vapour accelerated oxidation rate by more than an order of magnitude. The scale formed in Ar–21% O2 exhibited a duplex structure consisting of Fe2O3 outer scale and Cr-rich corundum type inner scale. Selective oxidation of Cr was hindered in Ar-21% O2–15% H2O, therefore Fe-rich (Fe, Cr, Ni)3O4 formed with Fe2O3 and Fe3O4 outer scale. The different structures and behaviour of Ni enrichment at alloy/scale interface were discussed. The oxidation of this alloy was compared with prior studies of Fe–Cr–Ni austenitic alloys.

► Water vapour accelerated the oxidation rate by more than an order of magnitude. ► Water vapour hindered selective oxidation of Cr due to higher oxygen permeability. ► The different behaviour of Ni enrichment at alloy/scale interface was discussed. ► The protectiveness of inner scale changes the oxygen potential distribution. ► Fe–Cr–Ni martensitic alloy did not show noticeable benefits over austenitic alloys.