Corrosion of AISI 316 and AISI 304 Stainless Steel with Iodine Vapor

摘要

The weight loss of stainless steel in corrosion with iodine vapor was studied at 500 to 1000 exp 0 C and an iodine vapor pressure range of 0.05 to 0.5 mm Hg, using a thermobalance. In the initial stage of corrosion, the weight loss rate is largely influenced by solution treatment or surface treatment; the induction period, observed for solution-treated samples, is shortened or eliminated by fission-fragment irradiation, ion-bombardment or mechanical polishing, and in some cases corrosion is even accelerated by the surface treatments. A constant weight loss region follows the initial stage of corrosion. In this region, the weight loss rate is not dependent on treatment to the samples, and has a linear relationship with the vapor pressure of iodine. The rate is the largest at about 800 and 750 exp 0 C for AISI 316 s. s. and AISI 304 s. s. The rates in general are larger for AISI 304 s. s. than for AISI 316 s. s. below 700 exp 0 C but almost the same above 800 exp 0 C. Corrosion product layer is observed on the surface of the sample below 700 exp 0 C. Based on these findings, the corrosion process is discussed. The deposition of corrosion product in a temperature gradient tube is also described. (ERA citation 06:006273)