Abstract: In order to investigate the evolution of microstructure and mechanical properties of cold drawn steel wire during annealing, annealing experiments were performed on the steel wire at different temperatures. The microstructure and dislocation density of the cross section of the steel wire before and after annealing were observed by means of scanning electron microscope (SEM) and transmission electron microscope (TEM), and the tensile properties and microhardness experiments were performed. The results show that under the condition of constant annealing temperature, the tensile strength of the steel wire increases first and then decreases on the whole with the increase of annealing time, while the elongation decreases first and then increases with the increase of annealing time. When the annealing time is 30 min, the higher the annealing temperature, the lower the tensile strength of the steel wire is. With the observation of microstructure, it is found that with the increase of annealing time, the spheroidization of cementite in the steel wire becomes more remarkable, and the dislocation density decreases.

Key words: cold drawn high carbon steel wire, annealing, mechanical properties, microstructure, spheroidization