Abstract:
Fe-0.4C-2Mn-4Al high strength steel was prepared by vacuum induction furnace melting, hot rolling, cold rolling and annealing processes. The influence of annealing temperature (650, 700, 750, 800 °C) on its microstructure and tensile properties was studied. The results show that the microstructure type of test steel after annealing at different temperatures was basically the same as those of the hot-rolled and cold-rolled test steel, all consisting of δ-ferrite, α-ferrite, cementite and fine κ-type carbides. As the annealing temperature increased, the δ-ferrite strips gradually disappeared and its degree of recrystallization increased, the grain size of α-ferrite increased, and the amount of carbides decreased. The distribution of α-ferrite and cementite was the most uniform after annealing at 750 ℃. The tensile curves of the test steel after annealing at different temperatures showed no obvious yield plateau, indicating that the test steel underwent continuous and uniform plastic deformation. With the increase of annealing temperature, the tensile strength and yield strength of the test steel showed an overall decreasing trend, and the percentage elongation after fracture increased. When the annealing temperature was 750 °C, the product of strength and ductility of the test steel was the largest, which was 14.28 GPa · %, and the work hardening ability was the best; the test steel had the best comprehensive performance.