A new steel with good low-temperature sulfuric acid dew point corrosion resistance

In this work, new steels (1#, 2#, and 3#) were developed for low-temperature sulfuric acid dew point corrosion. The mass loss rate, macro- and micro-morphologies and compositions of corrosion products of new steels in 10, 30, and 50% H ₂SO ₄ solutions at its corresponding dew points were investigated by immersion test, scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). The results indicated that mass loss rate of all the tested steels first strongly increased and then decreased as H ₂SO ₄ concentration increased, which reached maximum at 30%. Corrosion resistance of 2# steel is the best among all specimens due to its fine and homogeneous morphologies of corrosion products. The electrochemical corrosion properties of new steels in 10 and 30% H ₂SO ₄ solutions at its corresponding dew points were studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results demonstrated that corrosion resistance of 2# steel is the best among all the experimental samples due to its lowest corrosion current density and highest charge transfer resistance, which is consistent with the results obtained from immersion tests.