The surface structures of chromium steels of 15X5, 20X13, 12X17, and 1
5X28 grades were investigated by metallographic, x-ray diffraction, an
d x-ray microprobe methods. The independent variables were temperature
(800, 850, and 900 degrees C), time of exposure to a melt (2, 8, 20,
and 100 h), atmosphere maintained over the melt (argon or undesiccated
air), and the corrosion testing regime (anodic polarization or free c
orrosion).