Weld metal having excellent resistance to hydrogen embrittlement

Patent metadata

Field	Value
Publication number	US-9956650-B2
Application number	US-201314370877-A
Country	US
Kind code	B2
Filing date	Feb 25, 2013
Priority date	Feb 27, 2012
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

The present invention is a weld metal formed by gas shielded arc welding using a flux cored wire, the welded metal having a predetermined chemical composition, residual austenite particles being present in an amount of at least 2500 particles/mm 2 , and the volume fraction of residual austenite particles being at least 4.0%.

First claim

The invention claimed is:

1. A weld metal, comprising:
iron;
C: from 0.02 to 0.12 mass %;
Si: from 0.10 to 2.00 mass %;
Mn: from 0.90 to 2.5 mass %;
Ni: from 0.20 to 3.5 mass %;
Ti: from 0.040 to 0.15 mass %;
N: a positive amount less than or equal to 0.015 mass %; and
O: from 0.030 to 0.10 mass %;
wherein
the weld metal is obtained from a wire, which, based on a total mass of the wire, comprises
Si in a total content of from 0.35% to 2.5%;
Si in a form of metal Si in a content of 0.25% or more;
SiO 2 in a content of 0.25% or less;
Ti in a total content of from 2.5% to 4.5%;
Al in a total content of 0.10% or more;
Zr in a total content of 0.035% or more; and
Mg in a total content of 0.4% or more,
the wire has a value A calculated by Expression (a) of 0.30 or more and a ratio B calculated by Expression (b) of more than 4.0:
A value=Si—[Si/(Ti+2×Al+2×Zr+3.5×Mg)]  (a),

B ratio=(Mn+Ti)/Si  (b),

in the Expression (a) and the Expression (b), Si, Ti, Al, Zr, Mg, and Mn represent a total content of Si, Ti, Al, Zr, Mg, and Mn in the wire, respectively,
retained austenite particles exist at a density of greater than or equal to 2500 per square millimeter and in a volume fraction of greater than or equal to 4.0%, and
a β value represented by Formula (1) is greater than or equal to 75:
β value=320×[C]+50×[Si]+15×[Mn]+10×[Ni]+28×[Mo]  (1)

wherein [C], [Si], [Mn], [Ni], and [Mo] are the mass percent of C, Si, Mn, Ni, and Mo, respectively.

2. The weld metal of claim 1 , comprising:
Mo: less than 0.05 mass %.

3. The weld metal of claim 1 , wherein
Si: from 0.10 to 0.5 mass %,
Ni: from 1.0 to 2.0 mass %, and
an α value defined by Formula (2) is greater than or equal to 3.2:
α value=[Mn]+[Ni]+(2×[Mo])+(16×[Ti])−(12×[O])  (2)

wherein [Mn], [Ni], [Mo], [Ti], and [O] are the mass percent of Mn, Ni, Mo, Ti, and O, respectively.

4. The weld metal of claim 1 , wherein oxide particles exist at a density of greater than or equal to 5000 per square millimeter, with each particle containing greater than or equal to 20 mass % of Ti and having a circle-equivalent diameter of from 0.15 to 1.0 μm.

5. The weld metal of claim 1 , further comprising: at least one selected from the group consisting of
Cr: a positive amount less than or equal to 2.0 mass %,
V: a positive amount less than or equal to 0.60 mass %,
Nb: a positive amount less than or equal to 0.15 mass %,
Cu: a positive amount less than or equal to 1.0 mass %,
Al: a positive amount less than or equal to 0.020 mass %,
Zr: a positive amount less than or equal to 0.10 mass %, and
B: a positive amount less than or equal to 0.0050 mass %.

6. The weld metal of claim 1 , wherein
C: from 0.04 to 0.08 mass %;
Si: from 0.28 to 0.5 mass %;
Mn: from 1.5 to 2.0 mass %;
Ni: from 1.0 to 2.8 mass %;
Ti: from 0.055 to 0.08 mass %;
N: a positive amount less than or equal to 0.006 mass %; and
O: from 0.040 to 0.060 mass %.

7. The weld metal of claim 1 , further comprising:
Cr: a positive amount less than or equal to 2.0 mass %.

8. The weld metal of claim 1 , further comprising:
V: a positive amount less than or equal to 0.60 mass %.

9. The weld metal of claim 1 , further comprising:
Nb: a positive amount less than or equal to 0.15 mass %.

10. The weld metal of claim 1 , further comprising:
Cu: a positive amount less than or equal to 1.0 mass %.

11. The weld metal of claim 1 , further comprising:
Al: a positive amount less than or equal to 0.020 mass %.

12. The weld metal of claim 1 , further comprising:
Zr: a positive amount less than or equal to 0.10 mass %.

13. The weld metal of claim 1 , further comprising:
B: a positive amount less than or equal to 0.0050 mass %.

14. The weld metal of claim 1 , wherein the β value is 160 or less.

Assignees

• Kobe Steel Ltd

Inventors

• Nako Hidenori
• Kochi Takuya
• Urushihara Wataru
• Sato Munenobu
• Kitagawa Yoshihiko

Classifications

• B23K2203/04

  Operations & Transport · mapped topic

• C22C38/50

  with titanium or zirconium · CPC title

• B23K35/3053

  Fe as the principal constituent · CPC title

• B23K35/3073

  with Mn as next major constituent · CPC title

• C22C38/04

  containing manganese · CPC title