Effect of Graphite Solution as a Quenchant on the Corrosion Resistance of Steels

Owing to their cost-effective and comprehensive physical and chemical properties, steels are often utilized as structural materials in the construction of bridges, industrial equipment, marine vessels, and offshore platforms. Most of these steels are central components of load-bearing applications, which are usually exposed to harsh corrosion environments such as marine atmosphere, acid fog, and polluted industrial corrosive effluents. Conventional methods rely on coatings such as painting, electroplating, or galvanizing, which involve operational complexities, high costs, and environmental concerns. A potential solution to these disadvantages involves improving their inherent corrosion resistance through the refinement of the grain structure of alloy steels. In this study, the possibility of graphite solution as a quenchant for steel is explored. Since graphite has an excellent thermal conductivity of 2000 W/m K compared to water's conductivity of 0.598 W/m K, its quenching characteristics show promising results. In this study, the corrosion resistance of the steel samples was evaluated under both stagnant and flow-accelerated conditions. The graphite-quenched samples consistently demonstrated superior corrosion resistance compared to the water-quenched ones, particularly in a flow-accelerated environment. Microstructural analysis supported these findings, showing reduced surface degradation in graphite-quenched specimens. The Tafel plot analysis further confirmed the results, with the lower corrosion current density of graphite-quenched samples being shown in both stagnant and flow-accelerated conditions. Moreover, the graphite-quenched samples had a more positive corrosion potential, which indicates their greater electrochemical stability. This research highlights the potential of graphite-based quenchants as viable alternatives for applications that require enhanced corrosion resistance, without significantly compromising hardness.