Heat treatment process of H13 steel

1、 Pre treatment process

Annealing treatment

The forgings need to undergo isothermal spheroidization annealing: 860-890 ℃ × 2h → 740-760 ℃ × 4h → cooled in the furnace to 500 ℃
Complex molds require stress relief annealing at 600-650 ℃ for 2 hours after rough machining

2、 Quenching process parameters

Temperature and cooling control

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%

4、 Advanced reinforcement processing

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

5、 Key control points

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

1000 ℃ quenching+600 ℃ tempering: 620HV
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.