Investigation of the Role of Nitrogen in Cr18Mn15Mo1.5N Marine Steel

A new high-nitrogen steel (Cr18Mn15Mo1.5N) with a nitrogen content of 0.54% for marine engineering is prepared using a vacuum induction furnace and remelting furnace. The effects of nitrogen on the microstructure, yield strength, yield ratio, elongation, and corrosion resistance are studied by holding the experimental steel at 800, 900, 1000, 1100, and 1200 degrees C for 1, 3, and 5 h, respectively, which are compared with 316 steel series. The results of solution treatment show that the second phase includes Cr2N precipitates at 800 and 900 degrees C, the second phase dissolves at 1000 and 1100 degrees C, and ferrite precipitates at 1200 degrees C, respectively. The yield strength of Cr18Mn15Mo1.5N steel is 2.5 times that of 316 steel, and the plasticity is equivalent. The corrosion resistance of the experimental steel treated at 1100 degrees C for 1 h is 7.94 times better than that of 316 steel.