The Effect of Immersion Time on the Corrosion Behavior of Chromium-Diffused Layer in 1 M HCl Solution

Thermochemical treatments offer a cost-effective solution. These treatments promote the formation of a chromium diffusion layer, which significantly improves surface properties. Despite these improvements, the corrosion performance of treated surfaces remains a key area of research. This study investigated the electrochemical behavior of the Cr layer using electrochemical impedance spectroscopy (EIS) for measurements after immersing the surface in 1 M HCl solution for varying durations (1, 4, and 8 days) at an ambient temperature of 24 ± 2 °C. Surface morphology and corrosion products were examined further using Electron Probe Microanalysis (EPMA). After eight days of immersion, EPMA confirmed the formation of a compact, protective Cr2O3 layer. The chromium coating maintained its structural integrity without substrate attack. Despite the highly aggressive acidic medium, corrosion was still governed by selective chromium passivation. The results confirm that the chromium-coated layer efficiently limited chloride-induced pitting corrosion by forming a stable Cr2O3 passive barrier that preserved the integrity of the underlying X6Cr17 steel. These results highlight the potential of this layer for use in industrial environments such as acid pickling tanks, wastewater systems, and pharmaceutical manufacturing, where cost-effective corrosion resistance to hydrochloric acid media is required.