Abstract: Effects of annealing temperature, over-aging temperature and over-aging time on the microstructure and mechanical properties of cold rolled TRIP980 steel plate were studied. It is found that when the annealing temperature decreases from 800 ℃ to 760 ℃, with the decrease of austenitizing degree and the enhancement of original austenite stability, the hard phase content becomes lower and the retained austenite content becomes higher, macroscopically showing that the tensile strength decreases and the elongation increases. When the over-aging temperature increases from 360 ℃ to 400 ℃, the strength increases with the increase of bainite volume fraction. When the over-aging time increases from 600 s to 1500 s, the hard phase bainite softens and the stability of retained austenite increases, which result in the tensile strength decrease and the elongation increase.

Key words: cold rolled TRIP980 steel, annealing process, bainite, retained austenite, mechanical properties