2015年1月22日星期四

How to heat treatment for H13 mould steel

     1. Preheat treatment. The market of H13 mould steel are after annealing heat treatment in steel mill, to ensure that it has a good metallurgical structure, appropriate hardness, good processability, don't need annealing once more. But after forging in the processing factory, the original microstructure and properties were destroyed, an increase of forging stress, must be re annealing.
Isothermal spheroidizing annealing process: 860 ~ 890 °C heating insulation 2h, cooled to 740 to 760 °C isothermal 4h, furnace cooling to 500 DEG baked.
     2. Quenching and tempering. The mould quenching process specification (requirements good toughness):the heating temperature is 1020 ~ 1050 °C, oil cooling or air cooling, hardness of 54 ~ 58HRC. If the requirements of the H13 steel good hot hardness, the quenching process specification is: the heating temperature is 1050 ~ 1080 °C, oil cooling, hardness of 56 ~ 58HRC. Recommendation tempering temperature: 530 ~ 560 °C, hardness of 48 ~ 52HRC; tempering temperature 560 ~ 580 °C, hardness of 47 ~ 49HRC. Tempering should be performed twice. Tempering at 500 °C, the peak of tempering hardening occurs, the tempering hardness is highest, hardness about 55HRC, but the toughness is worst. Therefore, the tempering process should avoid 500 °C advisable. According to the mold use need, tempering at 540 ~ 620 °C is  better. Quenching should be performed preheated twice (600 ~ 650 °C, 800 ~ 850 °C), to reduce the thermal stress in the heating process.
     3. Chemical heat treatment. H13 mould steel if the gas nitriding or nitrocarburizing can make the mould is further strengthened, but the nitriding temperature should not be higher than the tempering temperature, to ensure that the core strength is not reduced, thereby improving the service life of the mould.


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The above article from Songshunsteel official website (http://www.songshunsteel.com/)
The original address: http://www.songshunsteel.com/news_show_27_22_52.html, reproduced please specify

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