S136 heat treatment:

___________ soft annealing

Under the protection state, after heated to 780 ℃ temperature in the furnace per hour the speed of 10 ℃, the cooling to 650 ℃, then put in air cooling.

2. Stress removal

After rough machining, which must be heated to 650 ℃, both temperature 2 hours later, the slow cooling to 500 ℃, and then put in air cooling.

3. Quenching

Preheat temperature: 600-600 ℃

Quenching temperature (austenitizing temperature) : 1020-1050 ℃

The commonly used temperature: 1030 ℃

℃ temperature holding time (minutes) before tempering hardness (HRC)

1020  30  56 ± 2

1050  30  57 ± 2

Heat preservation time = when the steel surface and center to achieve consistent after quenching temperature, to begin to calculate time of heat preservation in the furnace.

Quenching, must be protected to avoid decarburization and oxidation.

4. Cooling medium

Oil; Flow particle furnace or 250-550 ℃ graded quenching salt bath furnace, then cooling in the air; High-speed gas/have enough positive pressure of the gas in the vacuum furnace to mold to achieve the most appropriate features, in the mold deformation degree of acceptable conditions, cold speed the sooner the better. When in vacuum furnace heat treatment is recommended to use four or five bar pressure. Steel cooled to 50-70 ℃ (120-160 ° F) shall promptly tempering.

⒌ tempering

Tempering two times, each time after tempering, must be cooled to room temperature, minimum tempering temperature of 180 ℃ (applicable to small). Holding time at least two hours.

Note 1: the 250 ℃ tempering is recommended for the best combination of toughness, hardness and corrosion resistance.

Note 2: the austenitizing temperature should avoid to choose too high and too low tempering temperature < 250 ℃ combination, avoid the stress of the mould is too big.

Zhang shrinkage deformation and size of S136:

Quenching and tempering S136 time is long, the size of the high temperature easy to shrink, the material is not easy to shrink.