US 12,276,006 B2
Method of producing high-strength hot-dip galvanized steel sheet
Shunsuke Yamamoto, Tokyo (JP); Shotaro Terashima, Tokyo (JP); Yuki Takeda, Tokyo (JP); Michitaka Sakurai, Tokyo (JP); Katsuya Hoshino, Tokyo (JP); and Yoshiyasu Kawasaki, Tokyo (JP)
Assigned to JFE STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/760,362
Filed by JFE STEEL CORPORATION, Tokyo (JP)
PCT Filed Nov. 19, 2020, PCT No. PCT/JP2020/043279
§ 371(c)(1), (2) Date Aug. 9, 2022,
PCT Pub. No. WO2021/166350, PCT Pub. Date Aug. 26, 2021.
Claims priority of application No. 2020-028717 (JP), filed on Feb. 21, 2020.
Prior Publication US 2023/0082367 A1, Mar. 16, 2023
Int. Cl. C21D 9/46 (2006.01); C21D 1/26 (2006.01); C21D 6/00 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/06 (2006.01); C22C 38/08 (2006.01); C22C 38/12 (2006.01); C22C 38/16 (2006.01); C22C 38/28 (2006.01); C22C 38/32 (2006.01); C22C 38/38 (2006.01); C23C 2/02 (2006.01); C23C 2/28 (2006.01); C23C 2/40 (2006.01)
CPC C21D 9/46 (2013.01) [C21D 1/26 (2013.01); C21D 6/001 (2013.01); C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/06 (2013.01); C22C 38/08 (2013.01); C22C 38/12 (2013.01); C22C 38/16 (2013.01); C22C 38/28 (2013.01); C22C 38/32 (2013.01); C22C 38/38 (2013.01); C23C 2/02 (2013.01); C23C 2/022 (2022.08); C23C 2/0224 (2022.08); C23C 2/024 (2022.08); C23C 2/28 (2013.01); C23C 2/40 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method of producing a hot-dip galvanized steel sheet using a continuous hot-dip galvanizing apparatus including an annealing furnace in which a heating zone, a soaking zone, and a cooling zone are arranged side by side in the stated order and a hot-dip galvanizing line located downstream of the cooling zone, the method comprising:
subjecting a steel strip to annealing, by conveying the steel strip in the annealing furnace in an order of the heating zone, the soaking zone, and the cooling zone; and
subjecting the steel strip discharged from the cooling zone to hot-dip galvanizing using the hot-dip galvanizing line, to obtain a hot-dip galvanized steel sheet,
wherein the steel strip has a chemical composition containing, in mass %, Mn: 1.7% or more and 3.5% or less and Si: 0.4% or more and 1.05% or less and satisfying [Si]/[Mn]≤0.30, and
the chemical composition, a dew point of an atmosphere in the soaking zone, and a delivery temperature of the heating zone satisfy the following Formula (1):
A×50+B−C/30<140  (1)
where A=[Mn]−[Si]×4,
B=−0.0068×(D.P.)3−0.59×(D.P.)2−11.7×(D.P.)+120,
C=exp(T/100)/[Si],
[Si] is a concentration of Si in mass %, [Mn] is a concentration of Mn in mass %, D.P. is the dew point of the atmosphere in the soaking zone in ° C. where −50° C.<D.P.<−5° C., and T is the delivery temperature of the heating zone for the steel strip in ° C. where 400° C.<T<850° C.