First, uniform cooling liquid and its characteristics
In heat treatment production, the cooling medium is mainly used for quenching and cooling of the workpiece. Commonly used liquid coolants are clear water, organic and inorganic aqueous solutions, and various quenching oils, plus air and air cooling. These cooling media have a common feature: The cooling rate at which the workpiece is obtained varies greatly over the temperature at which they are used (here, the temperature of the workpiece). Figure 1 shows the cooling characteristics of clean water. Figure 2 shows the cooling characteristics of the base oil and the fast oil. It is easy to see that their cooling rate varies greatly with the temperature of the workpiece: mineral oil varies from 3 to 5 times, and aqueous media ranges from 5 to 15 times.
In air cooling and air cooling, the cooling rate obtained when the workpiece temperature is high is high, and the cooling speed obtained when the workpiece temperature is low is low. Figure 3 shows the cooling rate curve of the probe of the cooling characteristic meter when it is directly subjected to air cooling. It can be seen that the air cooling rate at 830 °C is about 2 to 3 times that at 400 °C. At the same time, the cooling rate increases as the wind speed increases, and decreases as the wind speed decreases. In addition, the probe has a high cooling rate in the windward position and a low cooling speed in the leeward position, as shown in Figure 4. The difference in size is also in the range of 2 to 3 times.
Then, is there any cooling medium whose cooling speed changes little with the temperature of the workpiece, and there is no difference between the windward and leeward sides? Our answer now is yes, that is, the company's recently introduced "even-speed coolant". Fig. 5 is a cooling rate curve of the uniform cooling liquid S1. It is a full-length constant coolant. Figure 6 shows the cooling rate curve of the uniform coolant S2. Above 350 °C, the cooling rate varies little with the probe temperature.
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