A study of mass transfer behaviors in the austenitic stainless steels exposed to sodium at high temperature

Type of phases and feature on corrosion surface and changes of composition and microstructure on cross section of type 316Ti and 321 austenitic stainless steels exposed to sodium at 650degC for 4000, 5000, 8000, 10000 hrs are examined by optical microscope, scanning electromicroscope, Auger spectrum instrument and X-ray diffractometer. The effect of mass transfer on the steels is obvious in the flowing sodium, carbon diffuses from the flowing sodium to the steels and nickel and chromium diffuse from the steels to the flowing sodium, it causes the changes of composition, type of phases and microstructure and decreasing corrosion resistance of the steels. (author)