1、 Pre treatment process
Annealing treatment
Complex molds require stress relief annealing at 600-650 ℃ for 2 hours after rough machining
2、 Quenching process parameters
Temperature and cooling control
| Process Type | Temperature | Cooling Method | Hardness(HRC) | Application |
| Standard Quenching | 1020-1050℃ | Air/oil cooling | 54-58 | General hot work dies |
| High-Temperature Quenching | 1050-1080℃ | Oil cooling | 56-58 | Die-casting dies |
| Low-Temperature Quenching | 950-1000℃ | Air cooling | 52-54 | High toughness dies |
Preheating requirements
Must be preheated twice: 600-650 ℃/800-850 ℃
Large molds (thickness>200mm) require three preheating cycles: 1 hour each at 600 ℃/800 ℃/850 ℃
3、 Tempering process specification
Temperature selection
Tempering at 530-560 ℃: Hardness 48-52HRC, while also considering toughness
560-620 ℃ tempering: suitable for high load conditions (47-49HRC)
Strictly prohibit tempering at 500 ℃ (although there is a 55HRC secondary hardening peak, the toughness drops sharply)
Number of tempering cycles
Two tempering processes are required, and the secondary tempering time for complex molds is extended by 50%
Chemical heat treatment
The gas nitriding temperature should be lower than the tempering temperature
Nitrocarburizing can increase surface hardness to 2.5 times that of the substrate
Cryogenic treatment
Processing at -70 ℃ for 1-3 hours after quenching can refine the grain size
Cooling after forging
Air cooling+sand cooling combination, cooling rate ≤ 5 ℃/min
Ingredient control
Carbon content of 0.32-0.45%, Cr/Mo/V forms nano carbides
6、 Typical process effect
1080 ℃ quenching+500 ℃ tempering: 55HRC secondary hardening peak value
Note: In practical applications, parameters need to be adjusted based on mold size and service conditions, and the uniformity of the structure needs to be verified through metallographic examination.