In recent years, the popularity of water-soluble quenching media in domestic fastener companies has become more widespread. In addition to medium- and low-carbon steels, products such as alloy steels, martensitic stainless steels, and hot work die steels are all attempting to use water-soluble quenching. Medium, and process control experience has become more and more mature, but there are often deviations in the control of the concentration of water-soluble quenching media, leading to various heat treatment quality problems.
At present, domestic heat-treatment quenching media for fastener companies mainly use rapid quenching oils and water-soluble quenching media. They are in direct contact with high-temperature parts during use. Inevitably, changes in physical and chemical properties will occur. Therefore, the cooling performance during use will be Some degree of change occurs and needs effective monitoring. One is to improve the stability of the quenching medium, to ensure that the performance and deformation of the quenched workpiece are within the controllable range; the second is to provide an effective cooling performance monitoring method, and at the same time, according to the working conditions, “tailor-made” quenching medium optimization program to ensure Quench medium long-term stable use.
From the point of view of production practices of most fastener companies, rapid quenching oils are mainly used for steels and thin-walled bolts, nuts, and special-shaped parts of alloy structural steels; water is mainly used for carbon structural steels and fasteners with simple shapes. PAG polymer quenching medium is between water and oil, which can replace water under certain conditions, and can also replace oil, with a wide range of cooling intensity.
The polymer quenching medium eliminates fumes generated from the quench oil. Reducing carbon emissions and promoting the use of polymer quenching media are global trends. The quenching medium of the polymer can completely meet the safety production requirements and can be confirmed as an important process material for the heat treatment and cleaning production of fasteners in China.
At present, polymer quenching media has become more and more widely used because of its unique advantages in environmental protection, technology, and cost. In recent years, in order to reduce the heat treatment fumes emissions, China has developed a variety of new quenching media for environmental protection and carbon reduction.
The use of current polymer quenching media accounts for approximately 30% to 40% of the entire quench medium (oil + polymer quench media). In production practice, in order to improve the quality of quenching, the reproducibility of the effect of the use of the polymer quenching medium is mainly determined by the reproducibility of the stirring, and the stirring is actually a turbulent flow. The temperature, concentration, and agitation of the polymer quenching media are the key factors in ensuring the quality of quenching.
Because the bacteria in PAG polymer quenching media use organic substances as raw materials and catalyze their changes, it will accelerate the aging of polymer quenching media, shorten the service life of quenching media, and increase the cooling speed during convection phase. The bolts and nuts will be deformed and cracked during quenching. The tendency is increased, so that the quenching quality of the fastener is difficult to guarantee. Only adjusting the concentration at the scene slows down the cooling rate, but the effect is not obvious. The use of bio-stabilized polymer quenching media AQ245 and an environmentally friendly fast-cooling agent can solve the problem of deformation and cracking.
Firstly, new liquids were used to configure different concentrations of quenching liquids, and the 300°C cooling rate of quenching liquids at different concentrations was tested by a cooling characteristic tester to establish standard tables or spectra of different concentrations and cooling rates. The use of cooling characteristic testers is ideal. method.
Secondly, it is best to exchange new oils once a year for quenching oils; water-soluble quenching media is different from quenching oils. Temperature, concentration and stirring intensity have a great influence on its cooling performance. It is recommended to use propellers for strong mixing to ensure uniform cooling. Sex, so as to obtain the uniformity of the organization and hardness.
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