Hot-dip galvanized steel sheet having excellent surface appearance and low-temperature bonding brittleness

Patent metadata

Field	Value
Publication number	US-11801665-B2
Application number	US-201917297266-A
Country	US
Kind code	B2
Filing date	Nov 28, 2019
Priority date	Nov 29, 2018
Publication date	Oct 31, 2023
Grant date	Oct 31, 2023

Abstract

Provided is a hot-dip galvanized steel sheet to be used for home appliances, vehicles, and the like, and having excellent surface appearance and low-temperature bonding brittleness. The hot-dip galvanized steel sheet includes: a base steel sheet; and a hot-dip galvanized layer formed on the base steel sheet. A surface of the base steel sheet has a centerline average roughness (Ra) of 0.3 or more, a roughness skewness (Rsk) of −1 or less, and a roughness kurtosis (Rku) of 6 or more.

First claim

The invention claimed is:

1. A hot-dip galvanized steel sheet having excellent surface appearance and low-temperature bonding brittleness, comprising:
a base steel sheet; and
a hot-dip galvanized layer formed on a surface of the base steel sheet,
wherein the surface of the base steel sheet has unevenness including a centerline average roughness (Ra) of 0.3 μm or more, a roughness skewness (Rsk) of −1 or less, and a roughness kurtosis (Rku) of 6 or more.

2. The hot-dip galvanized steel sheet of claim 1 , wherein a zinc grain (spangle) size of the hot-dip galvanized layer is 150 μm or less.

3. A method of manufacturing a hot-dip galvanized steel sheet having excellent surface appearance and low-temperature bonding brittleness, comprising operations of:
preparing a base steel sheet;
forming unevenness on a surface of the base steel sheet, the unevenness having a centerline average roughness (Ra) of 0.3 μm or more, a roughness skewness (Rsk) of −1 or less, and a roughness kurtosis (Rku) of 6 or more; and
forming a hot-dip galvanized layer by immersing the base steel sheet with the unevenness in a hot-dip galvanizing bath.

4. The method of claim 3 , wherein the forming of the unevenness includes: passing the base steel sheet between rolls on which unevenness is formed.

5. The method of claim 4 , wherein the unevenness formed on the rolls is formed by any one of SBT (Shot Blasting Texturing), LBT (Laser Beam Texturing), EDT (Electrical Discharging Texturing), and EBT (Electron Beam Texturing).

6. The method of claim 3 , further comprising: performing annealing heat-treatment of the base steel sheet for 30 to 180 seconds at 750 to 950° C. in a nitrogen atmosphere containing 5 to 40 vol% of hydrogen, before the immersing.

Assignees

• Posco
• Posco Co Ltd

Inventors

• Hwang Hyeon-Seok

Classifications

• B32B15/013 Primary

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

• B21B1/22

  for rolling {plates, strips,} bands or sheets of indefinite length (B21B1/42 takes precedence) · CPC title

• B21B1/227

  Surface roughening or texturing · CPC title

• B21B1/24

  in a continuous {or semi-continuous} process {(B21B1/224 takes precedence)} · CPC title

• B21B27/00

  Rolls, {roll alloys or roll fabrication}(shape of working surfaces required by special processes B21B1/00); Lubricating, cooling or heating rolls while in use · CPC title