Mechanical and surface characterization of interstitial‐free steel corroded under wet‐dry salt spray and immersion conditions: A comparative study

Abstract

AbstractHighly formable interstitial‐free steel has been subjected to corrode in wet‐dry salt spray (WDSS) and immersion corrosion (IMCC) conditions in 5, 10, 20, 30, and 45 days to investigate its corrosion behavior in simulated‐marine environment at the same temperature using 5 wt.% NaCl. The corrosion mechanisms and their effects have been studied and compared on the basis of weight loss and mechanical properties. Results revealed that corrosion rate in WDSS is about 9.5 times higher than IMCC. The corrosion coefficient (n) values for WDSS and IMCC have been observed as 0.99 and 0.35, respectively, which are evident for the protective nature of rust. The corrosion mechanisms and rust constituents may attribute different corrosion kinetics in both conditions. Moreover, the rate of degradation in yield strength and fracture strain in WDSS is 2 and 2.5 times higher than IMCC respectively; however, in the case of ultimate tensile strength the degradation rate is nearly same. It has also been observed that the higher pitting corrosion in WDSS may lead to change the failure mode from ductile to mix‐mode after 30 and 45 days of corrosion as authenticated from scanning electron microscopic images.