Method for hot-dip galvanizing a steel sheet

Patent metadata

Field	Value
Publication number	US-9512511-B2
Application number	US-91188306-A
Country	US
Kind code	B2
Filing date	Apr 14, 2006
Priority date	Apr 20, 2005
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

Exemplary embodiments of the present invention can provide a galvanization method for hot-rolled steel sheet, cold-rolled steel sheet, or plating sheet of various compositions, which can avoid nonplating defects by using an Ni preplating procedure. For example, an exemplary galvanization method can be provided for pickled hot-rolled steel sheet or annealed cold-rolled steel sheet which is free from non-plating defects which includes cleaning the surface of the plating sheet, preplating it with Ni, rapidly heating the sheet in a nonoxidizing or reducing atmosphere to a sheet temperature of about 430 to 500° C. at a heating a rate of about 20° C./sec or more, and then hot dip plating the sheet in a galvanization bath. The exemplary amount of Ni preplating can be determined based on the plate type and amount of Si in the sheet steel to produce a hot dip galvanization that is free from non-plating defects.

First claim

The invention claimed is:

1. A galvanization method for providing a plating sheet containing less than 0.09% Si, which is an annealed cold-rolled steel sheet, and which is configured to avoid non-plating defects, the method comprising:
an alkali degreasing treatment of the steel sheet;
a pickling treatment of the alkali degreased steel sheet in a sulfuric acid aqueous solution;
electroplating the pickled steel sheet with Ni in a sulfate ion containing plating bath;
preparing the electroplated steel sheet by heating said electroplated steel sheet in a reducing atmosphere to a sheet temperature between about 430° C. and about 500° C. at a heating rate between 20° C./sec and 50° C./sec; and
hot-dip plating the prepared steel sheet in a galvanization bath comprising between about 0.05% and about 1.0% Al,
wherein an amount of Ni applied during the electroplating is between about 0.05 g/m 2 and about 0.1 g/m 2 .

2. The method of claim 1 , further comprising further heating the hot-dipped prepared steel sheet and performing an alloying treatment.

Assignees

• Ishizuka Kiyokazu
• Nishimura Kazumi
• Kikuchi Ikuo
• Nippon Steel & Sumitomo Metal Corp

Inventors

• Ishizuka Kiyokazu
• Nishimura Kazumi
• Kikuchi Ikuo

Classifications

• C23C2/02 Primary

  Pretreatment of the material to be coated, e.g. for coating on selected surface areas (C23C2/30 takes precedence) · CPC title

• C23C2/06 Primary

  Zinc or cadmium or alloys based thereon · CPC title

• C23C2/28

  Thermal after-treatment, e.g. treatment in oil bath · CPC title

• C23C2/0224

  Two or more thermal pretreatments · CPC title

• C23C2/40

  Plates; Strips · CPC title