Heat treatment for S136

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Heat treatment for S136:
1.Soften annealing
In the state of gas protection, it is heated to the temperature of 780 ° C and reached the temperature uniformity,then cooling it down 650 ° C in a furnace at a rate of 10 ° C per hour, and cooling it in the air.

2. Stress removal
After roughing process, it must be heated to 650 ° C, after 2 hours of uniform temperature, slowly cooled to 500 ° C, and then placed in air to cool.

3. Quenching
Preheating temperature: 600-850 °C
Quenching temperature (austenification temperature): 1020-1050 °C
Common temperature: 1030 ° C

Temperature °C	Holding time (minutes)	before tempering hardness (HRC)
1020	30	56±2
1050	30	57±2

Holding time = When the surface and center of the steel reach a consistent quenching temperature, the holding time in the furnace is calculated.
It must be protected during quenching to avoid decarburization and oxidation.

4. Cooling medium
Oil; flow particle furnace or salt bath furnace 250-550 ° C classification quenching, and then cooled in high-speed air; gas in a high-speed gas / vacuum furnace with sufficient positive pressure to achieve the most appropriate characteristics of the mold, the degree of deformation of the mold is acceptable Under the conditions, the faster the faster the better. A pressure of 4-5 bar is recommended for heat treatment in a vacuum furnace. Steel should be tempered immediately after cooling to 50-70 ° C (120-160 ° F).

5. Tempering
Tempering twice, after each time tempering, it must be cooled to room temperature, the lowest tempering temperature is 180 ° C (for small pieces). Hold temperature for at least two hours.
Note 1: It is recommended to temper at 250 °C for the best combination of toughness, hardness and corrosion resistance.
Note 2: Avoid using a combination of too high austenitizing temperature and too low tempering temperature <250 °C to avoid too much stress on the mold.

S136 deformation and size of the contraction:
Time for quenching and tempering S136 is long, the temperature is high and the size is easy to shrink, If the un-loading method is not correct and it is easy to shrink.