Corrosion Resistance of PH13-8Mo Stainless Steel in 3.5% NaCl Solution

The pitting potentials of precipitation hardening stainless steels PH13-8Mo and 17-4PH in simulated sea water of 3.5% NaCl solution were investigated by means of potentiodynamic anodic polarization curves. The mechanism of corrosion resistance of stainless steel PH13-8Mo in seawater was analyzed by metallographic phase observe, scanning electron microscopy(SEM)and energy disperse spectroscopy. The results show that the average pitting potential and passive region of PH13-8Mo steel were bigger than those of steel 17-4PH, indicating that the corrosion resistance of PH13-8Mo steel is better than that of 17-4PH steel. The microstructure of aged steel PH13-8Mo is tempered martensite and massive precipitated phases. The good corrosion resistance of PH13-8Mo steel comes from enough passive elements of Cr, Ni and Mo which total percentage over 20% in its precipitated phases and matrix.