Research Progress on the Corrosion Resistance of Ultra- High-Strength Steels Modified by Ce Microalloying

Ultra-high-strength steels are widely used in critical components for construction machinery, ships, mining equipment, and automobiles because of their high toughness and weight-saving potential. However, under practical service conditions, especially in chloride-containing environments, these steels are highly susceptible to pitting corrosion and often exhibit poor passive film stability, which severely limits their service life. Owing to its strong affinity for oxygen and sulfur, rare-earth Ce can effectively purify molten steel, modify inclusions, and promote the densification of passive films, thereby improving corrosion resistance. In this context, green microalloying with Ce has emerged as a promising strategy and has attracted increasing attention in recent years. Although the influence of Ce on the corrosion behavior of ultra-high-strength steels has been widely investigated, a systematic understanding of its governing mechanisms is still lacking. This review summarizes the role of Ce in steels for construction machinery, with emphasis on its effects on inclusions, passive films, and electrochemical behavior, and discusses the relationship between Ce content and corrosion resistance. Finally, the potential of Ce microalloying for improving the corrosion performance of ultra-high-strength steels and future research directions are outlined.