Abstract: Microstructure of 25.8Mn-3.95Cr-2.83Al-0.33C-0.015N high-manganese TWIP steel after annealing at different temperatures and time was observed and analyzed by means of optical microscope and scanning electron microscope equipped with electron backscattering diffraction system, and its corrosion resistance was detected by using electrochemical workstation of standard three-electrode system. The results show that after annealing at 600-1000 ℃ for 25 min, the grains of the tested steel become larger sequentially with the increase of annealing temperature, and the proportion of Σ3 and Σ9 grain boundaries first increases and then decreases, reaching a maximum at 800 ℃. The full-scale corrosion resistance of the tested steel increases with the increase of annealing temperature, reaching an optimum at 1000 ℃, while the strongest localized corrosion resistance is achieved when annealing at 700 ℃. After annealing at 1000 ℃ for 5-25 min, the grain size of the tested steel also gradually augments with the increase of annealing time, the proportion of low-Σ grain boundaries also firstly increases and then decreases, the proportion of Σ3 and Σ9 grain boundary is the largest after annealing for 5 min, and the corrosion resistance is the best after annealing for 25 min.

Key words: high-manganese TWIP steel, annealing temperature, annealing time, microstructure, corrosion resistance