Comparison of Susceptibility to Intergranular Corrosion of 304 and 321 Stainless Steels Under Different Environmental Conditions by DLEPR method

In this study, the degree of sensitization was examined in AISI 304 and 321 type steels by DLEPR method whose experiments have been carried out on steels to examine and determine effect of NaCl, solution motion, pH and O2 on intergranular corrosion. It is seen that as NaCl molarity is increased, both activation and reactivation currents increase and this cause to increase on susceptibility to intergranular corrosion of both steels. In the absence of O2, the activation and reactivation values and degree of sensitization decrease. In addition, low speed of solution motion cause to decrease degree of sensitization of 304 steel. Increasing speed of solution motion will increase the degree of sensitization of 304 steel again. Increasing speed of the solution motion cause to decrease on degree of sensitization in all of the speeds. The increasing concentration of H2SO4 and decreasing pH cause to increase Ia, Ir and intergranular corrosion resistance of 321 steel. As decrease pH, at first the intergranular corrosion resistance of 304 has been increased and afterward decreased.