Heat Transfer Coefficient in Patenting Process with Hot Water

Abstract

Heat transfer coefficients were investigated in hot water patenting process in which austenitized steel wire rods are immersed in hot water containing 0.5% polyvinyl alcohol and subjected to cooling by film boiling, and following results are obtained. (temperature in the center of steel wire rods; 900650°C, rod diameter; d=515 mmφ)
(1) Heat transfer coefficient α is a function of rod diameter d, and following relation is obtained.α=kd^-0.25 (k : constant)
(2) α values for eutectoid steel rods having 5, 10, and 15 mm diameters are 300, 260, and 230 kcal/m². h·deg respectively when water temperature is boiling point.
(3) α increases greatly under sub-cool condition, i. e. by about 50% at 80°C in comparison with that at boiling temperature.