Welded joint of duplex stainless steel

Patent metadata

Field	Value
Publication number	US-9579870-B2
Application number	US-201213984321-A
Country	US
Kind code	B2
Filing date	Feb 10, 2012
Priority date	Feb 14, 2011
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

A welded joint of duplex stainless steel, which can suppress precipitation σ phase under high heat input welding, is excellent in SCC resistance under high-temperature chloride environments. A weld metal of the welded joint contains, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.0100%, Cu: at most 2.00%, Ni: 7.00 to 12.00%, Cr: 20.0 to 30.0%, Mo: 1 to 4%, N: 0.100 to 0.350%, sol. Al: at most 0.040%, and O: at most 0.035%, the balance being Fe and impurities. The weld metal satisfies Expressions (1) and (3):

2.2Cr+7Mo+3Cu>66  (1)

Cr+11Mo+10Ni−12(Cu+30N)<100  (3)

where a content (mass percent) of each element in one of the base metal and weld metal is used for each element in Expressions (1) and (3).

First claim

The invention claimed is:

1. A joint of duplex stainless steel comprising:
a base metal; and
a weld metal, wherein
the base metal consists of, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.0100%, Cu: more than 2.00% and at most 4.00%, Ni: 4.00 to 8.00%, Cr: 20.0 to 30.0%, Mo: 0.50 to 2.00%, N: 0.100 to 0.350%, and sol. Al: at most 0.040%, the balance being Fe and impurities,
the base metal satisfies Expression (1) and Expression (2),
the weld metal contains, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.010%, Cu: 0.10 to 0.8%, Ni: more than 8.00 and at most 12.00%, Cr: 20.0 to 30.0%, Mo: 1.00 to 4.00%, N: 0.100 to 0.350%, sol. Al: at most 0.040%, O: at most 0.035%, the balance being Fe and impurities, and
the weld metal satisfies Expression (1) and Expression (3):
2.2Cr+7Mo+3Cu>66  (1)

Cr+11Mo+10Ni−12(Cu+30N)<0  (2)

Cr+11Mo+10Ni−12(Cu+30N)<100  (3)

where a content (mass percent) of each element in one of the base metal and the weld metal is substituted into a symbol of each element in Expression (1) to Expression (3), wherein the joint has an area fraction of a sigma phase, which is less than 1%.

2. The joint of duplex stainless steel according to claim 1 , wherein
the weld metal further contains W: at most 4.00%, instead of part of the Fe.

3. The joint of duplex stainless steel according to claim 2 , wherein the Mo content of the base metal is 1.10 to 2.00%.

4. The joint of duplex stainless steel according to claim 1 , wherein the Mo content of the base metal is 1.10 to 2.00%.

5. A joint of duplex stainless steel comprising:
a base metal; and
a weld metal, wherein
the base metal consists of, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.0100%, Cu: more than 2.00% and at most 4.00%, Ni: 4.00 to 8.00%, Cr: 20.0 to 30.0%, Mo: 0.50 to 2.00%, N: 0.100 to 0.350%, and sol. Al: at most 0.040%, the balance being Fe and impurities,
the base metal satisfies Expression (1) and Expression (2),
the weld metal contains, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.010%, Cu: 0.10 to 0.8%, Ni: more than 8.00 and at most 12.00%, Cr: 20.0 to 30.0%, Mo: 1.00 to 4.00%, N: 100 to 0.350%, sol. Al: at most 0.040%, O: at most 0.035%, and V at most 1.50%, the balance being Fe and impurities, and
the weld metal satisfies Expression (1) and Expression (3):
2.2Cr+7Mo+3Cu>66  (1)

Cr+11Mo+10Ni−12(Cu+30N)<0  (2)

Cr+11Mo+10Ni−12(Cu+30N)<100  (3)

where a content (mass percent) of each element in one of the base metal and the weld metal is substituted into a symbol of each element in Expression (1) to Expression (3), wherein the joint has an area fraction of a sigma phase, which is less than 1%.

6. The joint of duplex stainless steel according to claim 5 , wherein
the weld metal further contains W: at most 4.00%, instead of part of the Fe.

7. The joint of duplex stainless steel according to claim 6 , wherein the Mo content of the base metal is 1.10 to 2.00%.

8. The joint of duplex stainless steel according to claim 5 , wherein the Mo content of the base metal is 1.10 to 2.00%.

9. A joint of duplex stainless steel comprising:
a base metal; and
a weld metal, wherein
the base metal consists of, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.0100%, Cu: more than 2.00% and at most 4.00%, Ni: 4.00 to 8.00%, Cr: 20.0 to 30.0%, Mo: 0.50 to 2.00%, N: 0.100 to 0.350%, and sol. Al: at most 0.040%, the balance being Fe and impurities,
the base metal satisfies Expression (1) and Expression (2),
the weld metal contains, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.010%, Cu: 0.10 to 0.8%, Ni: more than 8.00 and at most 12.00%, Cr: 20.0 to 30.0%, Mo: 1.00 to 4.00%, N: 0.100 to 0.350%, sol. Al: at most 0.040%, O: at most 0.035%, and at least one type selected from the group consisting of Ca: at most 0.0200%, Mg: at most 0.0200%, and B: at most 0.0200%, the balance being Fe and impurities, and
the weld metal satisfies Expression (1) and Expression (3):
2.2Cr+7Mo+3Cu>66  (1)

Cr+11Mo+10Ni−12(Cu+30N)<0  (2)

Cr+11Mo+10Ni−12(Cu+30N)<100  (3)

where a content (mass percent) of each element in one of the base metal and the weld metal is substituted into a symbol of each element in Expression (1) to Expression (3), wherein the joint has an area fraction of a sigma phase, which is less than 1%.

10. The joint of duplex stainless steel according to claim 9 , wherein
the weld metal further contains W: at most 4.00%, instead of part of the Fe.

11. The joint of duplex stainless steel according to claim 10 , wherein the Mo content of the base metal is 1.10 to 2.00%.

12. The joint of duplex stainless steel according to claim 9 , wherein the Mo content of the base metal is 1.10 to 2.00%.

13. A joint of duplex stainless steel comprising:
a base metal; and
a weld metal, wherein
the base metal consists of, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.0100%, Cu: more than 2.00% and at most 4.00%, Ni: 4.00 to 8.00%, Cr: 20.0 to 30.0%, Mo: 0.50 to 2.00%, N: 0.100 to 0.350%, and sol. Al: at most 0.040%, the balance being Fe and impurities,
the base metal satisfies Expression (1) and Expression (2),
the weld metal contains, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.010%, Cu: 0.10 to 0.8%, Ni: more than 8.00 and at most 12.00%, Cr: 20.0 to 30.0%, Mo: 1.00 to 4.00%, N: 0.100 to 0.350%, sol. Al: at most 0.040%, O: at most 0.035%, and rare earth metal: at most 0.2000%, the balance being Fe and impurities, and
the weld metal satisfies Expression (1 ) and Expression (3 ):
2.2Cr+7Mo+3Cu>66  (1)

Cr+11Mo+10Ni−12(Cu+30N)<0  (2)

Cr+11Mo+10Ni−12(Cu+30N)<100  (3)

where a content (mass percent) of each element in one of the base metal and the weld metal is substituted into a symbol of each element in Expression (1) to Expression (3),
wherein the joint has an area fraction of a sigma phase, which is less than 1%.

14. The joint of duplex stainless steel according to claim 13 , wherein
the weld metal further contains W: at most 4.00%, instead of part of the Fe.

15. The joint of duplex stainless steel according to claim 14 , wherein the Mo content of the base metal is 1.10 to 2.00%.

16. The joint of duplex stainless steel according to claim 13 , wherein the Mo content of the base metal is 1.10 to 2.00%.

17. A joint of duplex stainless steel comprising:
a base metal; and
a weld metal, wherein
the base metal consists of, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.0100%, Cu: more than 2.00% and at most 4.00%, Ni: 4.00 to 8.00%, Cr: 20.0 to 30.0%, Mo: 0.50 to 2.00%, N: 0.100 to 0.350%, and sol. Al: at most 0.040%, the balance being Fe and impurities,
the base metal satisfies Expression (1) and Expression (2),
the weld metal contains, in mass percent, C: at most 0.030%, Si: 0.20 to 1.00%, Mn: at most 8.00%, P: at most 0.040%, S: at most 0.010%, Cu: 0.10 to 0.8%, Ni:
more than 8.00 and at most 12.00%, Cr: 20.0 to 30.0%, Mo: 1.00 to 4.00%, N: 0.100 to 0.350%, sol. Al: at most 0.040%, O: at most 0.035%, V: at most 1.50%, instead of part of the Fe, and at least one type selected from the group cons

Assignees

• Nagayama Hiroyuki
• Yamada Kenta
• Hamada Masahiko
• Motoya Daisuke
• Amaya Hisashi
• Nippon Steel & Sumitomo Metal Corp

Inventors

• Nagayama Hiroyuki
• Yamada Kenta
• Hamada Masahiko
• Motoya Daisuke
• Amaya Hisashi

Classifications

• B23K2203/04

  Operations & Transport · mapped topic

• B23K9/173

  and of a consumable electrode · CPC title

• C22C38/001

  containing N · CPC title

• 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

• B23K35/3053

  Fe as the principal constituent · CPC title