Water-air spray cooling at heat treatment of cylindrical samples
Фролов Я.В. Водно-повітряне спрейерне охолодження при термічній обробці циліндричних зразків / Я. В. Фролов // Пластична деформація металів : матеріали наук.-практ. конф. : тез. допов., 22-26 травня 2017 р., м. Дніпро. – Дніпро : [б.в.], 2017. – С. 14-15.
Results of this study could be useful at researches of integrated manufacturing processes, including metal forming and subsequent heat treatment, with the purpose of achieving defined metal structure and properties of the product.
Spray cooling, according to the shape and size of the product and the specific consumptions of water and air provide the cooling rate in the range of 10...300 K/s. Such range gives good opportunities to manage the structure and properties of the metal. It let to perform processes like "quenching-tempering" and "quenching-aging". The difference in temperatures at the same time for all researched modes of cooling near the cooled surface (1 mm) for the experiments can be considered proportional to the distance between points of measurements with sufficient accuracy. At a depth of 5 mm an insignificant disturbance of proportionality of temperature changing at the cross section has been observed. Therefore, the distribution of temperature at the cross section of the sample requires further investigation for determining the limits of influence of sprayer cooling and the cooling effect through the sides of the sample.
Due to nonlinear form of temperature fall curves to obtain quantitative dependences of cooling rate from the parameters of spray cooling it is expedient usage of the temperature range (800 ... 500 °C) for the steel samples. Such way is similar to 8/5 cooling rate, widely used in welding techniques.
It was defined that the multiplication of relative water consumption at water-air sprayer cooling provides not proportional cooling rate with clear delay. The influence of relative water consumption on the cooling rate changes its character with growth of the distance from cooling surface to the axis.