he invention relates to a heat treatment process for strengthening and toughening a cold work die steel substrate, which belongs to the technical field of heat treatment of cold work die steel. The steps include: the first high temperature austenitizing: heating the raw material or mold blank to 1140~1180 ℃ at a heating rate of 30 ℃/h~50 ℃/h, holding it for 1~2h after reaching the temperature, and then oil cooling or rapid high pressure gas cooling to below 150 ℃; High temperature recovery treatment: the raw material or mold blank shall be immediately heated for recovery treatment at high temperature, charged at room temperature, and then heated with the furnace at a heating rate of 30 ℃/h~50 ℃/h, heated to 840 ‑ 860 ℃, kept for 1.9 ‑ 2.1h, and cooled to room temperature after being discharged; Second austenitizing; The third austenitizing; The high-temperature tempering treatment shall be repeated for 2 times continuously. The advantages are that the heat treatment technology of three times of austenitizing, one time of high temperature recovery treatment and two times of tempering treatment is adopted to improve the crack resistance, collapse toughness and fracture resistance of the cold-worked die steel of the die, and improve the adhesion resistance of the cold-worked die steel at the same time.
