1, Water

Water is the application of the earliest and most extensive, most economical -quenching medium; it is cheap, nontoxic, nonflammable, stable physical and chemical properties, and the cooling ability. By controlling the water temperature, increase the pressure, increasing the flow rate, the use of recycled water, the use of magnetic field, etc., can improve the cooling characteristics of water, and reduce distortion and cracking, to obtain an ideal quenching effect. However, these methods require specialized equipment to increase, and after quenching performance is not very stable, so there can not be widely used. So Water only for a small number of carbon content is not high, low and shape of the harden ability of steel quenching simple to use.

2 quenching oil

For the quenching of refined mineral oil is usually higher levels of neutral paraffin oil as base oil, it has a high flash point, low viscosity, less soot, oxidation resistance and good thermal stability, long life, etc. , suitable for quenching oil use. Quenching oil is only used in good harden ability, not the work piece thickness, shape complex and demanding quenching deformation of the work piece. Quenching oil on the surrounding environment, pollution, quenching can cause fire.

Affect the quenching oil cooling capacity of the main factors is the viscosity, low viscosity at room temperature, the oil is high-viscosity oil cooling capacity, temperature, oil flow increases, cooling capacity increased. Appropriate increase in the use of quenching oil temperature, oil can also increase the cooling capacity.

3 molten salt, molten alkali

This type of quenching medium is characterized by the cooling process is not made changes in biological state, quenching mainly by convection cooling, usually in the high-temperature region the cooling speed, slow cooling in the low-temperature region, quenching performance, strong harden ability, quenching side form a small, almost no cracks, but environmental pollution, poor working conditions, more energy, high cost, commonly used in the shape of the complex, cross-sectional dimensions of the work piece and change poor work hardening mold. Molten salts are sodium chloride, nitrate, nitrite, etc., in the salt bath quenching the work piece can obtain a higher hardness, and deformation is extremely small, easy to crack, usually used as a classification of isothermal quenching or quenching. The disadvantage is that molten salt easy to aging, oxidation and corrosion of the work piece with the role. Molten alkali are sodium hydroxide, potassium hydroxide, etc., it has a greater cooling capacity, heating the work piece if not oxidized, obtained after quenching the clean silver surface, there are certain applications. But melting alkali vapor is corrosive to skin stimulation, used to pay attention to ventilation and protective measures.



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