Vacuum gas quenching process

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Vacuum gasquenching medium

The cooling rate of vacuum air quenching is related to the type of gas, gas pressure, flow rate, furnace structure and furnace loading condition. Available gases are Ar, He, H, and N,. Assuming that the heat transfer rate of air under the same conditions is 1, then Ar is 0.70, He is 6, H is 7, and N2 is 0.99.

Key points of use

In high-pressure gas quenching, in order to quench high hardness, the pressure of the cooling gas is often increased. The quenching cooling rate increases significantly with the increase of air pressure, but the higher the air pressure, the better. For workpieces with larger size and smaller specific surface, under higher air pressure, the dominant factor determining the cooling rate is the internal heat conduction of the steel. Because the effect of convective heat transfer to accelerate cooling is difficult to reach the center of the workpiece. At this time, the effect of increasing the air pressure on increasing the cooling rate is not very obvious. Considering that the general vacuum furnace has a better sealing effect only when the pressure is lower than atmospheric pressure, and in order to save high-purity gas, the common pressure during vacuum air quenching is 0.5 × 105 ~ 0.8 × 105 Pa, and the highest is 0.92 × 105 ~ 0.99 ×10 5 Pa.

56NiCrMoV7 steel die-casting mold, the external dimensions are 247mm×268mm×400mm, the heating temperature is 890°C, the quenching pressure is 5bar, and the 530°C×2h tempering twice, 46~47HRC, with good metallographic structure.

Cr12MoV steel thread milling cutter, the external dimension is 135mm×37mm×37mm, heated at 1020℃×65min, high-purity nitrogen gas is introduced into the quenching, the quenching pressure is 5bar (1bar=105Pa), the tool core is cooled from 1020℃ to 500℃ For 45min, and then cooled to 80 ℃ after 15min, the process time is 4.2h. Surface hardness 63 ~ 64HRC.

Vacuum Quenching of Cold Work Die Steel Cr12

Preheat at 650-850 ℃ for 15 minutes, oil quench at 850-1100 ℃, then pass nitrogen, then temper and air-cool. Quenching temperature, quenching oil temperature, and cold room vacuum all affect its hardness, but the quenching temperature has the greatest influence. As the quenching temperature increases, the hardness increases gradually, and when the quenching temperature reaches 1000 °C, the hardness decreases as the temperature increases. The optimum quenching temperature is 1000℃.

Equipment selection: The RVGQ series vacuum air quenching furnace produced by SIMUWU is a high-quality product for the vacuum air quenching process of the tool and mold. The good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum air quenching process. SIMUWU specializes in the manufacture of vacuum furnaces, has more than ten years of relevant experience, and has a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum annealing furnace, vacuum oil quenching furnace, vacuum brazing furnace, etc., which are widely sold in developed and developing countries.