Zinc plated steel sheet having excellent fatigue strength of electrical resistance spot welds, and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-11981973-B2
Application number	US-202017779923-A
Country	US
Kind code	B2
Filing date	Dec 3, 2020
Priority date	Dec 3, 2019
Publication date	May 14, 2024
Grant date	May 14, 2024

Abstract

The present disclosure relates to a zinc plated steel sheet having excellent fatigue strength of electrical resistance spot welds and a method for manufacturing the same. According to an aspect of the present disclosure, a zinc plated steel sheet includes a base steel sheet and a zinc-based plating layer formed on a surface of the base steel sheet, wherein a concentration profile of one or two of oxygen, and silicon and manganese measured in a depth direction from the surface of the base steel sheet has a maximum point in the depth direction from the surface, and an absolute value of a difference between a depth at which the maximum point of the concentration profile of oxygen is formed and a depth at which the maximum point of the concentration profile of one of silicon and manganese is formed is 0.5 μm or less.

First claim

The invention claimed is:

1. A zinc plated steel sheet comprising:
a base steel sheet; and
a zinc-based plating layer formed on a surface of the base steel sheet,
wherein a concentration profile of oxygen, and a concentration profile of one or two of silicon and manganese measured in a depth direction from the surface of the base steel sheet have a maximum point in the depth direction from the surface, and
an absolute value of a difference between a depth at which the maximum point of the concentration profile of oxygen is formed and a depth at which the maximum point of the concentration profile of the one or two of silicon and manganese is formed is 0.5 μm or less.

2. The zinc plated steel sheet of claim 1 , wherein the depth at which the maximum point of the concentration profile of oxygen is formed is 4 to 15 μm.

3. The zinc plated steel sheet of claim 2 , wherein an oxygen concentration at the maximum point is 0.3 wt % or more.

4. The zinc plated steel sheet of claim 1 , wherein the depth at which the maximum point of the concentration profile of oxygen is formed is smaller than the depth at which the maximum point of the concentration profile of the one or two of silicon and manganese is formed.

5. The zinc plated steel sheet of claim 1 , wherein the concentration profile is measured by glow discharge optical emission spectrometry (GDOES).

6. The zinc plated steel sheet of claim 1 , wherein a coating weight of the zinc-based plating layer is 30 to 70 g/m 2 .

7. The zinc plated steel sheet of claim 1 , wherein the steel sheet has a composition comprising 0.05 to 1.5% of C, 2.0% or less of Si, 1.0 to 30% of Mn, 3% or less of S—Al (acid-soluble aluminum), 2.5% or less of Cr, 1% or less of Mo, 0.005% or less of B, 0.2% or less of Nb, 0.2% or less of Ti, 0.2% or less of V, 0.1% or less of Sb+Sn+Bi, and 0.01% or less of N.

Assignees

• Posco

Inventors

• Kang Ki-Cheol
• Lee Chung-Hwan

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C21D1/74

  Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material · CPC title

• C21D8/0273

  Final recrystallisation annealing · CPC title

• C21D8/0236

  Cold rolling · CPC title

• C21D8/0226

  Hot rolling · CPC title