Environmental Effects on Intergranular StressnCorrosion Cracking (IGSCC) of Sensitized StainlessnSteel in High-Temperature Solutions

摘要

The effect of relevant environmental variables on the IGSCC of furnace sensitized AISI 304 stainless steel in dilute aqueous solutions has been studied at temper¬atures ranging from 100 to 275℃ using the slow strain rate technique. The signi¬ficance of a critical potential above which IGSCC occurs (EtSCC) has been dis¬cussed on the basis of literature data for both the current normal operating BWR environment and that modified by the injection of hydrogen. The effect of pH on EISCC in solutions containing Na2SO4 and H2SO4 has been determined, as well as the effect on the IGSCC behavior of aqueous impurities such as chloride and sulfide, thiosulfate, cupric and lead ions. In addition, the role of low molecular weight carboxylic acids, such as formic, acetic and oxalic has been evaluated in water over a wide range of dissolved oxygen concentrations. Finally, the effect of fluid flow velocity on the IGSCC has been studied using slow strain rate rests and AC impedance methods to determine the influence of oxide film properties on the initiation of intergranular cracks under various flowing conditions.