Welding processes for iron-base ultra fine grained materials and structural components manufactured by the processes

• US 20030047587A1
• Filed: 02/25/2002
• Published: 03/13/2003
• Est. Priority Date: 03/15/2001
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Okamoto, Kazutaka, Doi, Masayuki, Ishibashi, Ryo, Okamura, Hisanori, Aono, Yasuhisa
• Granted Patent: US 6,585,148 B2
• Time in Patent Office: Days
• US Class Current: 228/112.1
• CPC Class Codes: B23K 20/1265 Non-butt welded joints, e.g. overlap-joints, T-joints or spot welds
• CPC Class Codes: B23K 20/129 specially adapted for particular articles or workpieces
• CPC Class Codes: B23K 20/227 with ferrous layer
• CPC Class Codes: C21D 9/50 for welded joints

Abstract

Structural components obtained by a process welding iron-base materials, where the iron-base material is iron-base fine grained materials free from any amorphous phase, which comprises welding two kinds of fine grained materials of chemical and crystallographically same or different kinds from one another, whose average grain sizes d are in a range of 10 nm<d≦5×10³ nm, etc., by friction stir welding can maintain distinguished properties of fine grained materials, such as strength and corrosion resistance.

Claims

1. A process for welding iron-base materials, which comprises welding the same or different kinds of iron-base materials, at least one of which is an iron-base ultra-fine grained material free from any amorphous phase and having an average grain size d in a range of 10 nm<

d≦

5×

10³ nm, by friction stir welding.

17. A process for welding iron-base materials according to claim 1, wherein the welding is carried out in any of coolants including water, oil and an inert gas or while straying the coolant in the vicinity or over the entirety of welding zones.

2. A process for welding iron-base materials, where the iron-base materials are iron-base ultra-fine grained materials free from any amorphous phase, which comprises welding two kinds of the ultra-fine grained materials of chemically and crystallographically same or different kinds with one another, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, by friction stir welding.

3. A process for welding iron-base materials, where the iron-base materials are iron-base ultra-fine grained materials free from any amorphous phase, which comprises welding one kind of the ultra-fine grained materials, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm with another kind or other kinds of the grained materials of chemically and crystallographically same or different kinds, whose average grain sizes d are in a range of 5×

10³ nm<

d, by friction stir welding.

4. A process for welding iron-base materials, where the iron base materials are austenitic stainless steel, which comprises welding two kinds of the stainless steel from one another, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, by friction stir welding.

5. A process for welding iron-base materials, where the iron-base materials are austenitic stainless steel, which comprises welding one kind of the fine grained stainless steel, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, with another kind of the stainless steel, whose average grain sizes d are in a range of 5×

10³ nm<

d, by friction stir welding.

6. A process for welding iron-base materials, where the iron-base materials are ferritic stainless steel with not more than 0.12 wt. % C, free from any of martensite phase and tempered martensite structure, which comprises welding two kinds of the stainless steel with one another, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, by friction stir welding.

7. A process for welding iron-base materials, where the iron-base materials are ferritic stainless steel with not more than 0.12 wt. % C, free from any of martensite phase or tempered martensite structure, which comprises welding one kind of the fine grained stainless steel, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, with another kind of the stainless steel, whose average grain sizes d are in a range of 5×

10³ nm<

d, by friction stir welding.

8. A process for welding iron-base materials, where the iron-base materials are two-phase stainless steel, which comprises welding two kinds of the stainless steel, whose existing austenite phase and ferrite phase average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, respectively, by friction stir welding.

9. A process for welding iron-base materials, where the iron-base materials are two-phase stainless steel, which comprises one kind of the fine grained stainless steel, whose existing austenite phase and ferrite phase average grain sized d are in a range of 10 nm<

d≦

5×

10³ nm, with another kind of the stainless steel whose existing austenite phase and ferrite phase average grain sizes d are in a range of 5×

10³ nm<

d, by friction stir welding.

10. A process for welding iron-base materials, where the iron-base materials are austenitic stainless steel, ferritic stainless steel and two-phase stainless steel of fine grained materials, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, which comprises welding two of the different kinds of the stainless steel, with one another by friction stir welding.

11. A process for welding iron-base materials, which comprises one kind of austenitic stainless steel, ferritic stainless steel and two-phase stainless steel of fine grained materials, whose average grain sizes are in a range of 10 nm<

d≦

5×

10³ nm, with another different kind of said three kinds of the stainless steel, whose average grain sizes d are in a range of 5×

10³ nm<

d, by friction stir welding.

12. A process for welding iron-base materials, where the iron-base materials are ferritic steel of fine grained materials with not more than 7 wt. % Cr and with a ferrite phase base metal, and carbon steel, which comprises welding two kinds of the steel, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10 ³ nm, by friction stir welding.

13. A process for welding iron-base materials, where the iron-base materials are ferritic steel with not more than 7 wt. % Cr and with a ferrite phase base metal, and carbon steel, which comprises welding one kind of the steel of fine grained materials, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, with another kind of said steel, martensitic stainless steel and mild steel, whose average grain sizes d are in a range of 5×

10³ nm<

d, by friction stir welding.

14. A process for welding iron-base materials, which comprises welding one kind of austenitic stainless steel, ferritic stainless steel and two-phase stainless steel of fine grained materials, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, with another kind of ferritic steel with not more than 7 wt. % Cr and with a ferrite phase base metal, whose average grain sizes d are likewise in a range of 10 nm<

d≦

5×

10³ nm, and carbon steel, by friction stir welding.

15. A process for welding iron-base materials, which comprises welding one kind of austenitic stainless steel, ferritic stainless steel and two-phase stainless steel of fine grained materials, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, with another kind of martensitic stainless steel, ferritic steel comprising a ferrite phase with not were than 7 wt. % Cr, whose average grain sizes d are in a range of 5×

10³ nm<

d, carbon steel and mild steel, by friction stir welding.

16. A process for welding iron-base materials, which comprises welding one kind of ferritic steel of fine grained materials, whose average grain sizes d are in a range of 10 nm<

d≦

5×

10³ nm, with not more than 7 wt. % Cr and with a ferrite phase base metal, and carbon steel with another kind of austenitic stainless steel, ferritic stainless steel and two-phase stainless steel, whose average grain sizes d are in a range of 5×

10³ nm<

d, by friction stir welding.

18. A structural component obtained by welding of the same or different kinds of iron-base materials, at least one of which is an iron-base ultra-fine grained material free from any amorphous phase and having an average grain size d in a range of 10 nm<

d≦

5×

10³ nm, by friction stir welding, wherein at least a joint being tempered or annealed.

19. A structural component according to claim 18, wherein the iron-base ultra-fine grained material having an average grain size d in a range of 10 nm<

d≦

5×

10³ nm is one member selected from the group consisting of carbon steel, martensitic stainless steel, mild steel and ferritic stainless steel containing Cr in an amount of 7% by weight or less, and the joint obtained by friction stir welding is tempered or annealed at 600°

C. to 850°

C.