The effect of dominant alloy additions on the corrosion behavior of some conventional and high alloy stainless steels in seawater

The corrosion behavior of some conventional and high alloy austenitic, ferritic and duplex stainless steels has been studied at 50 °C in Gulf seawater. The alloys were tested under salt spray conditions and corrosion rates were determined by applying the electrochemical polarization resistance technique. The pitting behavior was studied using the potentiodynamic polarization technique. Both exposure and accelerated tests were employed to study crevice corrosion. The effect of surface finish on crevice attack was investigated in detail. Critical crevice solution pH (CCSpH), an important crevice corrosion parameter, was determined by a method based on the Oldfield and Sutton mathematical modelling of corrosion in chloride media [J.W. Oldfield and W.H. Sutton, Br. Corros. J. 13, 13 (1978)]. The relationship between pitting potential Epit and pitting resistance equivalent PREN is discussed. The results of the study indicate that the presence of alloying elements such as Cr, Mo and N has a significant and beneficial influence on the pitting and crevice corrosion resistance of stainless steels.