Spheroidizing annealing method of MnCr series low-carbon gear steel

The invention discloses a spheroidizing annealing method of MnCr series low-carbon gear steel, which comprises the following steps: (1) heating the gear steel to a first temperature, and preserving heat at the first temperature for 1-4 hours, the first temperature being 760-800 DEG C; (2) the gear steel subjected to heat preservation in the step (1) is cooled to a second temperature, and then heat preservation is conducted for 6-10 h at the second temperature; and then the gear steel subjected to heat preservation is taken out of the furnace and air-cooled to the room temperature, and the second temperature is 640-700 DEG C. By adopting the spheroidizing annealing method, the uniformity of the annealed structure of the MnCr-series low-carbon gear steel can be improved, and the impact energy, the percentage reduction of area and the hardness of the MnCr-series low-carbon gear steel can be improved; the MnCr series low-carbon gear steel suitable for cold extrusion is obtained, and the annealing method is low in