Oxidation characteristics of duplex stainless steel 2205 in simulated combustion atmosphere

High temperature oxidation of duplex stainless steel 2205 was carried out in the simulated combustion atmosphere of natural gas (i.e. 3% O-2-10% CO2-18% H2O-N-2) from 1100 to 1260 degrees C by means of weight gain, X-ray diffraction and scanning electron microscope. The results show that the initial oxidation kinetics submits to parabolic law and nodules are formed at about 1180 degrees C. The oxidation rate increases slowly from 1100 to 1220 degrees C but dramatically at 1260 degrees C because of the fast growth of nodules. The nodules consist of three thin oxide layers, i.e. the external Fe-rich oxides, the mid-Fe-Cr spinels and the internal Cr-rich oxides. It is suggested that the reheating temperature should be below 1180 degrees C for removing the oxide scales in pickling.