In water cooling of hot steels, a cooling capacity (
H) is influenced by water temperature(θ
w). The authors analyzed the effect of water temperature on the cooling capacity by using the data of authors' and other reseachers' experiments. The coefficient of water temperature
Rb [°C
-1], which is the contribution factor of water temperature to the cooling capacity, is defined as
Rb=[
H(θ
b+Δθ)-
H(θ
b-Δθ)]/[
H(θ
b)×2·Δθ], where θ
b and Δθ are basic temperature and temperature difference from θ
b, respectively. By introducing the idea of
Rb, the effect of θ
w on
H in many experiments has been analysed systematically. The mian results obtained are as follows:
1) The values of
Rθb, 5 (θ
b:30, Δθ:5), which correspond to the typical temperature of cooling water in production mills, exist within the range of -0.01 to -0.02°C
-1. This result means that the values of
H change_??_(1 to 2)% with ±1°C variation of θ
w.
2) The absolute
Rθb, 5 -value of laminar coolings is larger than that of spray coolings.
3) It seems that the values of
Rb are influenced by sizes and surface conditions of a steel to be cooled, flow conditions of cooling water on a cooled surface, and so on.
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