Steel sheet, hot-dip galvanized steel sheet and galvannealed steel sheet
US-2020325554-A1 · Oct 15, 2020 · US
Welded member of galvanized steel sheets
US12221701B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-12221701-B2 |
| Application number | US-202418622583-A |
| Country | US |
| Kind code | B2 |
| Filing date | Mar 29, 2024 |
| Priority date | Dec 19, 2018 |
| Publication date | Feb 11, 2025 |
| Grant date | Feb 11, 2025 |
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- Title
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- Abstract
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Abstract
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A welded member includes: a first steel sheet including a base steel sheet and a zinc-based plating layer formed on a surface of the base steel sheet; and a second steel sheet spot-welded on the first steel sheet and facing the zinc-based plating layer of the first steel sheet, a spot-welded zone being formed between the first steel sheet and the second steel sheet. A surface layer of the base steel sheet has a decarburization ratio of 30% or more. The decarburization ratio is represented by equation: Decarburization ratio (%) of surface layer=(1−average carbon concentration in surface layer/bulk carbon concentration)*100 where the surface layer refers to a region of the base steel sheet from the surface thereof to a depth of 35 μm. A shoulder portion of the spot-welded zone includes a B-type crack having a length of 100 μm or less, and no C-type crack.
First claim
Opening claim text (preview).
What is claimed is: 1. A welded member including: a first steel sheet including a first base steel sheet and a first zinc-based plating layer formed on a surface of the first base steel sheet; and a second steel sheet spot-welded on the first steel sheet and facing the first zinc-based plating layer of the first steel sheet, a first spot-welded zone being formed between the first steel sheet and the second steel sheet, wherein a surface layer of the first base steel sheet has a decarburization ratio of 30% or more, the decarburization ratio being represented by equation 1 as below, Decarburization ratio (%) of surface layer=(1−average carbon concentration in surface layer/bulk carbon concentration)*100 where the surface layer refers to a region of the first base steel sheet from the surface thereof to a depth of 35 μm, [Equation 1] wherein a shoulder portion of the first spot-welded zone includes a B-type crack having a length of 100 μm or less, and no C-type crack. 2. The welded member of claim 1 , further comprising: a third steel sheet spot-welded on an opposite side of the second steel sheet, a second spot-welded zone being formed between the first steel sheet and the third steel sheet, wherein the third steel sheet includes a same steel sheet as the first steel sheet, and wherein a shoulder portion of the second spot-welded zone includes a B-type crack having a length of 100 μm or less, and no C-type crack. 3. The welded member of claim 1 , wherein the second steel sheet includes a same steel sheet as the first steel sheet. 4. The welded member of claim 1 , wherein the decarburization ratio of the surface layer is 40% or more. 5. The welded member of claim 1 , wherein a tensile strength of the first steel sheet is 490 Mpa or more. 6. The welded member of claim 1 , wherein a coating amount of the first zinc-based plating layer is 30-70g/m 2 . 7. The welded member of claim 1 , wherein the first zinc-based plating layer is an hot-dip galvannealed (GA) layer having a degree of alloying of 8-13 weight %. 8. The welded member of claim 1 , wherein the first base steel sheet has a composition including, by weight ratio, 0.05-1.5% of C, 2.0% or less of Si, 1.0-30% 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
Inventors
Classifications
during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title
Two or more thermal pretreatments · CPC title
by cleaning or etching · CPC title
in a reactive atmosphere, e.g. oxidising or reducing atmosphere (C23C2/024 takes precedence) · CPC title
Thermal after-treatment, e.g. treatment in oil bath · CPC title
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- What does patent US12221701B2 cover?
- A welded member includes: a first steel sheet including a base steel sheet and a zinc-based plating layer formed on a surface of the base steel sheet; and a second steel sheet spot-welded on the first steel sheet and facing the zinc-based plating layer of the first steel sheet, a spot-welded zone being formed between the first steel sheet and the second steel sheet. A surface layer of the base …
- Who is the assignee on this patent?
- Posco Co Ltd
- What technology area does this patent fall under?
- Primary CPC classification C23C2/02. Mapped technology areas include Chemistry & Metallurgy.
- When was this patent published?
- Publication date Tue Feb 11 2025 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 7 related publications on this page (citations in our corpus or others sharing the same primary CPC).