Effects of temperature variations on oxidation of iron-20% chromium alloysat 1200 K in Ar-20% O-2-Cl-2 gas mixtures

Oxidation of an Fe-20%Cr alloy has been investigated at 1200 K in gas mixtu res of Ar-20%O-2 with additions of 0.05 to 1.0%Cl-2 with temperature cycles to room temperature at 12 h intervals. The metals experience accelerated o xidation which proceeds via a chloride vapor transport mechanism and produc es a porous oxide scale. The temperature cycles trigger accelerated oxidati on in gas mixtures which would not produce accelerated oxidation under isot hermal conditions. The results indicate that chlorine and temperature cycle s have a synergistic effect on the oxidation rates.