DETERMINATION OF RESISTANCE TO PITTING ANDCREVICE CORROSION OF STAINLESS STEELS BY USINGELECTROCHEMICAL METHODS

摘要

The resistances to pitting and crevice corrosion for various stainless steels were evaluated bymeasuring critical pitting temperature (CPT), critical crevice temperature (CCT) and critical crevicepotential (CCP). CPT values obtained from immersion tests were compared with those done byelectrochemical test methods. The relationship between CPT and CCT was investigated in terms ofPREN (pitting resistance equivalent index). The effect of types of crevice former, block-type and washertypeon CCT was examined. CCP (critical crevice potential) values for different stainless steels weremeasured and compared with their CCT values. Results showed that CPT and CCT increased withincreasing PREN and the linear relationship was established between CPT and CCT values measured byimmersion tests. CCT values obtained from immersion tests were independent of types of crevice formersuch as block-type or washer-type. CCT increased with increasing PREN while CCP increased withincreasing PREN up to 40, approaching the constant values above 40.