EFFECT OF TEMPERATURE ON THE CREVICE CORROSION OF TYPE-304 STAINLESS-STEEL IN CHLORIDE SOLUTION UP TO 250-DEGREES-C

The effect of temperature on the corrosion behavior of type 304 (UNS(1) S30400) stainless steel (SS) with crevice was compared with that without a crevice up to 250-degrees-C in 0.5 M NaCl solution. The electrochemical stepwise cyclic polarization technique was employed to determine the crevice corrosion potential (E'(crev)) and the repassivation potential (E(R)(crev)). Furthermore, the highest potential below which no crevice corrosion generated (E(crev)) was determined by the potentiostatic polarization test and was compared with E(R)(crev)) at each temperature. The difference between the characteristic potential values for crevice corrosion (E'(crev) and E(R)(crev)) and corresponding ones for pitting (E'(pit) and E(R)(pit)) decreased with temperature, and they almost coincided at 150-degrees-C. This coincidence reflected the corrosion mode that pitting was dominant at 150 through 200-degrees-C irrespective of a crevice. On the other hand, typical general dissolution inside the crevice was observed below 80-degrees-C and at 250-degrees-C. The previous finding by Tsujikawa et al. that E(R)(crev) coincided with E(crev) at ambient temperature was also confirmed at elevated temperature.