Abstract: Taking 0.19 mm T4 cold-rolled tinplate as the research object, annealing and over-aging annealing simulation tests were carried out by using a Gleeble-3500 thermal simulator, and the effect of annealing temperature on microstructure and properties of the T4 tinplate was analyzed. The results show that the recrystallization start temperature of the tested tinplate is about 575 ℃, and the recrystallization end temperature is 640-670 ℃. When the over-aging annealing temperature is 560 ℃, the tested steel is in the initial stage of recrystallization. When the over-aging annealing temperature is higher than 575 ℃, the recrystallization degree becomes more sufficient with the increase of annealing temperature. The recrystallization nucleation is accomplished when the over-aging annealing temperature reaches 640 ℃, and the distortion-free new grains are gradually formed. Besides that, the hardness of the annealed T4 tinplate decreases with the increasing of over-aging annealing temperature, the hardness decreases significantly (by 49 HV) from 540 ℃ to 640 ℃ due to recrystallization but only by 9 HV from 640 ℃ to 670 ℃.

Key words: T4 tinplate, over-aging annealing, recrystallizing temperature, microstructure, hardness