Spallation Behavior of Oxide Scale on Stainless Steels

The spallation behavior of oxide scale on a ferritic stainless steel and a austenitic stainless steel during cooling after oxidation in air at 1273 K for 100 h were investigated by dynamic visual observation. The spallation spread as minor spallation that was generated in a scattered pattern. The spallation for the ferritic and austenitic stainless steels started at 770 K and above 983 K (at which the temperature measurement was started) respectively. The masses of spalled scale for the ferritic and austenitic stainless steels began to increase dramatically below 473 and 673 K, respectively. The spallation unit size of the ferritic stainless steel was larger than that of the austenitic stainless steel. It was considered that the scale was spalled by the thermal stress generated during cooling. The strain energy accumulated by the thermal stress were discussed with respect to the above results.