On 2018-08-08 14:48:54
Choice of quenching cooling medium
Bearing parts of the quenching cooling medium of choice for effective wall thickness in 1 ~ 5 mm ring type of product should be in different specifications of the interrupted quenching oil or "tailored" bearing special quenching oil is given priority to, because they have the characteristics of high temperature, high ignition point, flash point steam membrane phase is short, break the membrane capability, low temperature cooling speed is slow, quenching stress is small, so the quenching distortion and thermal oxidation stability, has a long-term, stable cooling performance, easy to clean, long service life.
Effective thickness in 6 ~ 10 mm ring, should use the corresponding fast bright quenching oil or "tailored" fast bearing special quenching oil, their strong cooling capacity, high temperature and cooling speed, low temperature cooling rate is moderate, can make bearing parts to obtain high and even hardness, and can well control the quenching deformation, bearing surface easy to clean after quenching, thermal oxidation stability, long service life.
Quench oil in a decade of use, since the furnace carbon black and debris into the purity of quenching oil pollution, the need to match a high-speed centrifugal purifier to filter impurities, it does not change the quenching oil chemical and physical properties, in situations where conditions permit, suggested that each configuration a net oil machine, heat treatment workshop to protect the purity of the quenching oil, improve the brightness is of great benefit. It is also possible to use decarbonizing agent to periodically remove carbon and impurities from oil products.
Effective thickness of 10 mm or ring, should be used under the salt bath quenching agent for markov interrupted quenching or bainite isothermal quenching, special of nitrate quenching medium composition is fixed and mixed evenly, high purity, calcium magnesium iron and other impurities, use for a long time after the accumulation of salt slag, good salt bath flow, bearing parts nitrate quenching surface after cleaning, uniform color, salt bath of long service life.
In the effective thickness of the bearing ring 1 mm or less precision small micro ring quenching, you need to use the vacuum quenching, quenching oil vacuum quenching oil distillation range is narrow, the saturation vapor pressure is extremely low, antioxidant ability, less volatile, easy pumping air into vacuum state, light and easy to clean, oil with less consumption, good thermal oxidation stability, long service life, temperature in 40 ~ 60 ℃ is better, but the demand bearing parts cleaning after drying can enter into a vacuum furnace, after vacuum quenching ring clean bright metal color.
According to the size of the rolling quenching can be selected according to the size of the fast and bright quenching oil and water-soluble quenching medium, in the effective thickness of >10mm, can be used ACR, PAG or PVP and other types of water-soluble quenching medium, the quenching intensity of the use of high concentration, and vice versa.