High-strength galvanized steel sheet and production method therefor

Patent metadata

Field	Value
Publication number	US-2016017471-A1
Application number	US-201414772468-A
Country	US
Kind code	A1
Filing date	Feb 28, 2014
Priority date	Mar 5, 2013
Publication date	Jan 21, 2016
Grant date	—

Abstract

A high-strength galvanized steel sheet whose base steel is a high-strength steel sheet contains Si, Mn, and B and has good coating adhesiveness. A base steel sheet containing Si, Mn, and B is oxidized at a heating temperature of steel sheet T that satisfies the formula, and then subjected to reduction-annealing and galvanizing
T ≧58.65×[Si]+29440×[B]−13.59×[O 2 ]+548.1
[Si]: amount of Si in the steel on a mass percent basis [B]: amount of B in the steel on a mass percent basis [O 2 ]: O 2 concentration on a volume percent basis in an atmosphere at oxidizing treatment.

First claim

1 .- 5 . (canceled)

6 . A method of producing a high-strength galvanized steel sheet comprising:
oxidizing a steel sheet containing Si, Mn, and B at a heating temperature of T° C. that satisfies formula (1), reduction-annealing the oxidized base steel sheet, and galvanizing the reduction-annealed base steel sheet
T ≧58.65×[Si]+29440×[B]−13.59×[O 2 ]+548.1  (1)

wherein: [Si]: content of Si in the base steel sheet on a mass percent basis [B]: content of B in the base steel sheet on a mass percent basis [O 2 ]: O 2 concentration on a volume percent basis in an atmosphere at oxidizing treatment.

7 . The method according to claim 6 , further comprising, after galvanizing, performing an alloying treatment at a temperature of 460° C. to 600° C. for 10 to 60 seconds.

8 . The method according to claim 6 , wherein the base steel sheet has a composition consisting of on a mass percent basis, C: 0.01 to 0.20%, Si: 0.1 to 2.0%, Mn: 1.0 to 3.0%, B: 0.0005 to 0.005%, and the balance being Fe and unavoidable impurities.

9 . A high-strength galvanized steel sheet produced by the method according to claim 6 , wherein, in a base steel sheet surface layer having a thickness of 5 μm under a coating layer, an amount of Si oxides is 0.05 g/m 2 or more on a Si basis and an amount of Mn oxides is 0.05 g/m 2 or more on a Mn basis.

10 . A high-strength galvanized steel sheet produced by the method according to claim 7 , wherein, in a coating layer, an amount of Si oxides is 0.05 g/m 2 or more on a Si basis and an amount of Mn oxides is 0.05 g/m 2 or more on a Mn basis, and in a base steel sheet surface layer having a thickness of 5 μm under the coating layer, an amount of Si oxides is 0.01 g/m 2 or less on a Si basis and an amount of Mn oxides is 0.01 g/m 2 or less on a Mn basis.

11 . The method according to claim 7 , wherein the base steel sheet has a composition consisting of, on a mass percent basis, C: 0.01 to 0.20%, Si: 0.1 to 2.0%, Mn: 1.0 to 3.0%, B: 0.0005 to 0.005%, and the balance being Fe and unavoidable impurities.

12 . A high-strength galvanized steel sheet produced by the method according to claim 8 , wherein, in a base steel sheet surface layer having a thickness of 5 μm under a coating layer, an amount of Si oxides is 0.05 g/m 2 or more on a Si basis and an amount of Mn oxides is 0.05 g/m 2 or more on a Mn basis.

13 . A high-strength galvanized steel sheet produced by the method according to claim 8 , wherein, in a coating layer, an amount of Si oxides is 0.05 g/m 2 or more on a Si basis and an amount of Mn oxides is 0.05 g/m 2 or more on a Mn basis, and in a base steel sheet surface layer having a thickness of 5 μm under the coating layer, an amount of Si oxides is 0.01 g/m 2 or less on a Si basis and an amount of Mn oxides is 0.01 g/m 2 or less on a Mn basis.

Assignees

• Jfe Steel Corp

Inventors

• Makimizu Yoichi
• Suzuki Yoshitsugu
• Nagataki Yasunobu

Classifications

• C21D9/46

  for sheet metals · CPC title

• C23C2/34

  characterised by the shape of the material to be treated (C23C2/14 takes precedence) · CPC title

• B32B15/013

  one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium · CPC title

• C23C2/02 Primary

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

• C23C8/14

  Oxidising of ferrous surfaces · CPC title