Corrosion response of ultra-high strength steels used for automotive applications

Abstract

The corrosion resistance properties of two ultra-high strength steels, Docol 1200 and
\n1400 were studied in 3.5 wt% NaCl solution using chemical and electrochemical
\ntechniques supported by surface characterization techniques namely scanning electron
\nmicroscope (SEM), energy dispersive spectroscopy (EDX), atomic force microscope
\n(AFM), and optical profilometer. The mechanical properties of both Docol 1200 and
\nDocol 1400 uncorroded and corroded were determined by tensile test. Results obtained
\nreveal that the two alloys exhibit similar mechanical properties. Corrosion has effect on
\nthe mechanical properties of the alloys. Corrosion studies reveal that both Docol 1200
\nand 1400 are prone to corrosion in NaCl environment. A corrosion rate of 30.6 mpy and
\n49.6 mpy was recorded for a Docol 1200 at 25 °C and 60 °C, respectively. For Docol
\n1400, the corrosion rate obtained at 25 °C and 60 °C was 32.7 mpy and 52.4 mpy,
\nrespectively. Docol 1200 is adjudged to exhibit superior corrosion resistance property
\nthan Docol 1400. The optical profilometric results disclose that Docol 1200 and Docol
\n1400 suffered pitting corrosion in NaCl solution. Pitting corrosion was more severe with
\nDocol 1400 than 1200.