Passivation and corrosion behavior of LDSS 2101 in calcium sulfoaluminate cements with different temperatures

Abstract

Calcium Sulfoaluminate cement (CSA) is more suitable than Ordinary Portland cement (OPC) for emergency repair and protection engineering due to its rapid hardening and high early strength. However, the low alkalinity of CSA and the complex temperature environment can accelerate steel corrosion. This study investigates the feasibility of lean duplex stainless steel 2101 (LDSS 2101) as an economic-techno substitute for 304 stainless steels (304SS) and low-carbon (LC) steel in CSA systems. Considering the complex temperature variations, seven temperature-controlled CSA pore solutions were prepared, including four constant temperature (5℃, 20℃, 55℃ and 80℃) and three alternating temperatures (5–55°C, 20–55°C and 5–80°C). The OPC pore solutions were also prepared as a comparison. The passivation behavior of LDSS 2101 in CSA and OPC pore solution at different temperatures was investigated through various electrochemical testing and surface analysis techniques. LDSS 2101 could form passivation films in CSA and OPC solutions at different temperatures, and the Al element promoted the formation of a more protective and thicker passivation film in the CSA solution compared to the OPC solution. Accordingly, compared with OPC solution, the corrosion resistance of LDSS 2101 in CSA solution was improved even in harsh corrosive environments. Notably, the durability of LDSS 2101 was similar to that of 304SS while maintaining economical. LDSS 2101 with lower Ni content can serve as an economical alternative to austenitic stainless steel for CSA systems at various service temperatures, which is particularly significant for enhancing durability and saving life cycle costs in emergency repair engineering utilizing CSA in extreme working conditions.