Patent ID: 11093670

Abstract:
A hot-dip coating equipment includes a cooling rate determining device that includes: a coefficient obtaining section configured to obtain coefficients α, β, γ, and δ associated with the hot-dip coating bath, in the following equation that expresses a degree of discoloration YI of the surface of a hot-dip coated steel sheet; and a rate determining section configured to determine an average cooling rate A so as to allow the YI of the following Expression (1) to be not more than a predetermined reference value, YI =(α×[SE]+β)×{(T−ST)/A}1/2+γ×[SE]+δ . . . (1), where: [SE] is a concentration (mass %) of a specific element contained in the hot-dip coating bath; T is a temperature (° C.) of the hot-dip coating bath; and ST is a solidification temperature (° C.) at which the hot-dip coating bath is solidified.