METHOD FOR MANUFACTURING HOT-DIP GALVANIZED STEEL SHEET

WIPO Patent Application WO/2020/148944

A1

Provided is a method for manufacturing a hot-dip galvanized steel sheet having excellent surface appearance, plating adhesion properties and corrosion resistance. The method for manufacturing a hot-dip galvanized steel sheet according to the present disclosure is characterized by comprising: a first annealing step of retaining a steel sheet having a component composition containing, in % by mass, 0.10 to 3.0% inclusive of Si and 1.0 to 10.0% inclusive of Mn in a temperature range from 650 to 900°C inclusive for 30 seconds or longer in a reducing atmosphere containing hydrogen and having a dew point of -65 to -20°C inclusive, and then cooling the resultant steel sheet; a step of forming a Fe coating film at an adhesion amount of 0.3 g/m2 to 10.0 g/m2 inclusive on the surface of the steel sheet; a second annealing step of retaining the steel sheet in a temperature range from 700 to 900°C inclusive for 30 seconds or longer in a reducing atmosphere containing hydrogen and having a dew point of 0°C or lower wherein the highest reachable temperature of the steel sheet is 900°C or lower, and then cooling the resultant steel sheet; and a step of subjecting the steel sheet to a hot-dip galvanization procedure.

WO/2006/042930	HOT-DIP COATING METHOD IN A ZINC BATH FOR STRIPS OF IRON/CARBON/MANGANESE STEEL
WO/2013/108624	STEEL STRIP CONTINUOUS ANNEALING FURNACE AND CONTINUOUS ANNEALING METHOD
WO/2004/063410	HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET AND METHOD FOR PRODUCING THE SAME

AOYAMA MAI (JP)
SUZUKI YOSHITSUGU (JP)

PCT/JP2019/038021

July 23, 2020

September 26, 2019

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JFE STEEL CORP (JP)

C23C2/02; C21D9/46; C22C38/00; C22C38/04; C22C38/60; C23C2/06; C23C2/40

JPH0971851A	1997-03-18
JP2015504976A	2015-02-16
JPS60187625A	1985-09-25
JP2011214102A	2011-10-27
JP2011214102A	2011-10-27
JP2005200694A	2005-07-28

See also references of EP 3913106A4

SUGIMURA Kenji (JP)

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