High corrosion resistant hot dip Zn alloy plated steel sheet

• US 9,302,449 B2
• Filed: 12/26/2011
• Issued: 04/05/2016
• Est. Priority Date: 12/28/2010
• Status: Active Grant

• Current Assignee: POSCO Co. Ltd. (Posco Holdings Incorporated)
• Original Assignee: Posco Holdings Incorporated
• Inventors: Kim, Sang-Heon, Jin, Young-Sool, Oh, Min-Suk, Kim, Su-Young, Yoo, Bong-Hwan
• Primary Examiner(s): LA VILLA, MICHAEL EUGENE
• Application Number:
  US13/824,445
• Publication Number:
  US 20130183541A1
• Time in Patent Office: 1,562 Days
• Field of Search: 428/659, 428/621, 428/658, 428/681, 428/684, 428/685, 428/687, 428/332, 428/336, 428/335, 428/334, 428/340, 428/341, 428/704
• US Class Current: 1/1
• CPC Class Codes: B32B 15/013 one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
• CPC Class Codes: C23C 2/06 Zinc or cadmium or alloys based thereon
• CPC Class Codes: C23C 2/20 Strips; Plates
• CPC Class Codes: C23C 2/261 in a gas atmosphere, e.g. inert or reducing atmosphere
• CPC Class Codes: C23C 2/29 Cooling or quenching
• CPC Class Codes: Y10T 428/12535 with additional, spatially distinct nonmetal component
• CPC Class Codes: Y10T 428/12799 Next to Fe-base component [e.g., galvanized]
• CPC Class Codes: Y10T 428/12972 Containing 0.01-1.7% carbon [i.e., steel]
• CPC Class Codes: Y10T 428/12979 Containing more than 10% nonferrous elements [e.g., high alloy, stainless]
• CPC Class Codes: Y10T 428/12993 Surface feature [e.g., rough, mirror]
• CPC Class Codes: Y10T 428/27 Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]

Abstract

Provided is a hot dip zinc (Zn) alloy plated steel sheet having excellent corrosion resistance and surface qualities, and a method of manufacturing the same. For this purpose, provided is a high corrosion resistant hot dip Zn alloy plated steel sheet which includes an underlying steel sheet and a hot dip Zn alloy plating layer, wherein a composition of the hot dip Zn alloy plating layer includes 1 to 3 wt % of aluminum (Al), 1.5 to 4.0 wt % of magnesium (Mg), and Zn and unavoidable impurities as a remainder, in which Al+Mg is in a range of 2.5 to 7.0 wt % and Al: (Al+Mg) ratio is in a range of 0.38 to 0.48, and a method of manufacturing the high corrosion resistant hot dip Zn alloy plated steel sheet.

Claims

1. A high corrosion resistant hot dip zinc (Zn) alloy plated steel sheet comprising:

an underlying steel sheet; and

a hot dip Zn alloy plating layer,

wherein a composition of the hot dip Zn alloy plating layer includes about 2.3 wt. % to about 3 wt. % of aluminum (Al), about 1.5 wt. % to about 3.3 wt. % of magnesium (Mg), and Zn and unavoidable impurities as a remainder, in which Al+Mg is in a range of about 3.8 wt. % to about 6.3 wt. % and Al/(Al+Mg) is a weight ratio in a range of about 0.41 to about 0.48, wherein the hot dip Zn alloy plated steel sheet is subjected to skin pass rolling, and wherein a surface roughness (Ra) of the hot dip Zn alloy plated steel sheet is about 2 μ

m or less before performing the skin pass rolling, and wherein the hot dip Zn alloy plating layer comprises a plated structure, in which a Zn—

MgZn₂ binary eutectic structure is dispersed in a matrix of a Zn—

Al—

MgZn₂ ternary eutectic structure, a Zn single phase structure is included in an amount of about 10% by area or less, and a MgZn₂ structure is included as a remainder.

2. The high corrosion resistant hot dip Zn alloy plated steel sheet of claim 1, wherein the plating layer further comprises one or more selected from the group consisting of silicon (Si), lithium (Li), titanium (Ti), lanthanum (La), cerium (Ce), boron (B), and phosphorous (P) in total amount of about 0.1 wt. % or less.

3. The high corrosion resistant hot dip Zn alloy plated steel sheet of claim 1, wherein phosphorous (P) is adhered to a surface of the plating layer and a content thereof is in a range of about 0.1 mg/m² to about 500 mg/m².