When the red die works, it bears huge and periodic hot extrusion and punching pressure. At the same time, when the blank metal is plastically deformed, it also causes strong friction on the die surface. Therefore, the failure of the die is mainly repeated thermal stress except for wear and tear. Fatigue damage due to mechanical stress. Therefore, to improve the life of the mold should be considered from the aspects of high temperature strength, fracture toughness, cold and heat fatigue crack propagation rate and so on. Technological measures. Forging and pre-heat treatment of mold blanks eliminates the directionality of the rolled material and metallurgical defects in the core of the material. It is necessary to repeatedly perform upsetting and lengthening to improve the material carbide morphology and distribution uniformity.
The initial forging temperature is 1100°C and the light hammer rapid forging is started. The final forging temperature is about 850°C. The final forging temperature should not be too high to prevent the precipitation of secondary carbides along the grain boundaries to form network carbides and thus the mechanical properties of the forgings. The change is not good, but it should not be too low. Below 850°C, the completeness of the recrystallization cannot be guaranteed, and the forging may be plastically deficient due to the presence of work hardening, and may easily form cracks. After forging, the forgings should be slowly cooled with the furnace. Forging blanks are isothermally annealed. After annealing, the requirements of the organization: pearlite 1-4, mesh carbide ≤ 2 grade, ribbon carbide ≤ 3, hardness 207 ~ 255HBS.
Improve the quenching temperature 3Cr2W8V quenching heating temperature is only heated to above 1100 °C, the inside of the carbides such as WC, VC are all dissolved in the austenite, so it can increase the number of lath martensite, reduce carbide, is conducive to improve Fracture toughness K1C; increase the quenching temperature can also improve the red die strength, thermal stability, help to improve its thermal fatigue toughening heat treatment process.
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