Abstract: The corrosion test of ultra purified 165 wt%Cr ferritic stainless steel containing Cu and Sn was carried out by immerging the specimens into the 6 wt% FeCl3 solution at 35 ℃， and the polarization curves of the steel were measured using potentiodynamic polarization method. The influence of grain size on the corrosion resistance of ferritic stainless steel was investigated. The corrosion rates were calculated through gravimetric tests. The results show that the pitting potential of the stainless steel greatly rises with the coarsening of grain size. There is a relative reasonable range of grain size and overfined or overcoarsened grain size are unbeneficial for the corrosion resistance of the tested steel.

Key words: ferritic stainless steel, grain size, corrosion resistance, pitting potential, polarization curve