| Corrosion behavior of austenitic stainless steel containing Ti has been studied by using electrochemical techniques. The samples containing Ti from 0.1 to 1.0 wt% were solutionized at 1050℃ for lhr and then sensitized at 650℃ for 5hr under argon atmosphere. Microstructure and phase analysis of the samples after heat treatment and corrosion tests were carried out by using XRD, TEM, SEM and optical microscope. The amount of a-ferrite and TiC precipitates in matrix increased as the Ti content increased. In the sensitized samples, Cr_(23),C_6 precipitates were observed at γ/δ interface. Degree of sensitization(DOS) was lower than 1.0 in all of the solutionized samples and the sensitized samples of Ti content above 0.4 wt% whereas the sensitized samples of Ti content lower than 0.4 wt% showed DOS higher than 1.0. Intergranular attack appeared mainly at grain boundaries in the sensitized sample containing 0.1 wt% Ti and at the γ/δ interface of the higher Ti content. In the latter, however, the attack was not so severe. Pitting potential(E_(put)) and repassivation potential(E_(tep)) of the solutionized and sensitized samples were increased with increasing Ti content. The number and size of the pits decreased with increasing Ti content in the sensitized samples. The pits nucleated at Cr_(23)C_6 site and the γ/δ interface. |
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