The influence of flow rate and temperature on the quenching effect of cooling water

냉각수의 유동속도와 온도가 담금효과에 미치는 영향

It has already been known that quenching effect is influenced greatly by stirring and changing coolant's temperature on quenching. But according to the past investigations its effect has not been taken into consideration quantitatively in the cooling process. The purpose of this study is that the influence of flow rate and temperature on the quenching effect of cooling water as quenching medium is quantitatively examined by using the open channel. The stream of water in this study is turbulent flow. The temperature of the specimen made of pure copper is measured by CA thermocouple in the vicinity of the surface and recorded by an automatic recorder during the quenching process in city water. The results obtained are as follows; 1. The quenching effect of cooling water generally increases with Reynolds Number(characteristic length; specimen diameter)as shown in the experimental formula; but at the realm of Reynolds Number from 1.2 * 10$^{4}$ to 9.2 * 10$^{4}$, the increasing rate of quenching effect shows little increase. 2. The increasing rate of quenching effect was increased under the flow rate of 221 cm/sec. On the other hand, it was decreased below this flow rate. 3. The quenching effect was influenced by the water temperature and the flow rate. But it was rather dependent upon the former than the latter. 4. Although the quenching effect appeared loosely in the water temperature of 50.deg. C, it was shown that the quenching effect increased in the low flow rate of 31 cm/sec. comparing with the still water. 5. It is desirable to design the quenching system to be over 1.2 * 10$^{4}$ in Reynolds Number or over, 3000$cm^{-1}$ / in V/v in order to increase the quenching effect of the system using open channel.annel.