Tribocorrosion behavior of low-temperature plasma-carburized AISI 420 martensitic stainless steel: Investigating the synergy between corrosion and erosion in slurry and liquid impingement environments

Erosion-corrosion is a significant concern across industries, impacting equipment lifespan and efficiency. When erosion-corrosion occurs, the resulting damage becomes complex, often leading to greater mass loss than that observed with erosion or corrosion alone. Martensitic stainless steels (MSSs) are commonly used in such environments due to their favorable combination of mechanical and corrosion resistance. However, under severe tribocorrosive conditions, it is necessary to apply surface treatments to prevent rapid steel degradation. Carburizing treatment is known to independently enhance the corrosion and erosion resistance of MSS. Nonetheless, there is a limited understanding of the impact of carburizing on the synergy between corrosion and erosion in such steels. In this study, we examined two different tribocorrosion conditions, assessing the resistance to slurry erosion and liquid impingement erosion for both carburized and non-carburized AISI420 MSS specimens exposed to a corrosive agent (from an electrochemical test using a 3.5 %-NaCl solution). To provide a basis for comparison, a static corrosion test was also performed to evaluate the environmental impact, with the electrolyte at rest, without flow or particles. Our findings revealed that the carburized layer is responsible for reducing the corrosion current density and increasing corrosion potential of AISI420 MSS. In contrast, slurry and liquid impingement erosion result in an increased corrosion current density and a decreased corrosion potential. The parameters omega and omega' (role of carburizing on the relationships between 'slurry erosion and corrosion' and 'liquid impingement erosion and corrosion' mechanisms interaction, respectively) demonstrated that carburizing application mitigates the impact of slurry and liquid impingement erosion, respectively. Additionally, the carburizing treatment reduces the corrosion rate, total mass loss, and erosion-induced mass loss of the studied samples, minimizing the synergy between erosion and corrosion. Finally, the interactions between the degradation modes reveal that erosion predominantly governs the AISI420 MSS deterioration process.