Cr-containing austenitic alloy tube and method for producing the same

Patent metadata

Field	Value
Publication number	US-9255319-B2
Application number	US-201113819072-A
Country	US
Kind code	B2
Filing date	Aug 12, 2011
Priority date	Aug 26, 2010
Publication date	Feb 9, 2016
Grant date	Feb 9, 2016

Abstract

There is provided a Cr-containing austenitic alloy tube, wherein a chromium oxide film with a thickness of 0.05 to 1.5 μm having the relationship defined by Formula (i) is formed on the inner surface of the tube, wherein the average concentration of C in the depth range of 5 to 10 μm from the inner surface is lower than the concentration of C in a base metal;

0.4≦δ1/δ2≦2.5  (i)

wherein δ1 and δ2 are thicknesses (μm) of the chromium oxide film at both ends of tube, respectively.

First claim

What is claimed is:

1. A Cr-containing austenitic alloy tube exhibiting corrosion resistance and enhanced strength, wherein the Cr-containing austenitic alloy tube consists of, by mass percent, C: 0.01 to 0.15%, Si: 1.00% or less, Mn: 2.0% or less, P: 0.030% or less, S: 0.030% or less, Cr: 10.0 to 40.0%, Ni: 8.0 to 80.0%, Ti: 0.5% or less, Cu: 0.6% or less, Al: 0.5% or less, and N: 0.01 to 0.20%, a balance being Fe and impurities, and wherein a chromium oxide film with a thickness of 0.05 to 1.5 μm having a relationship defined by Formula (i) is formed on an inner surface of the tube, wherein an average concentration of C in a depth range of 5 to 10 μm from the inner surface is lower than a concentration of C in a wall thickness central portion of the tube;
0.4≦δ1/δ2≦2.5  (i)

wherein δ1 and δ2 are thicknesses (μm) of the chromium oxide film at both ends of tube, respectively.

2. The Cr-containing austenitic alloy tube according to claim 1 , wherein the tube has a length of 5 to 50 m and an inside diameter of 10 to 30 mm.

3. The Cr-containing austenitic alloy tube according to claim 2 , wherein the Cr-containing austenitic alloy tube is used as a member for a nuclear power plant.

4. A method for producing a Cr-containing austenitic alloy tube described in claim 3 , wherein the Cr-containing austenitic alloy tube is heated under the condition that the tube is held in the temperature range of 800 to 1200° C. for one minute or longer with flowing a nonoxidizing gas containing water vapor with a concentration of 250 to 25,000 ppm through the tube at a flow rate in the range of 6.0 to 50 L/min.

5. A method for producing a Cr-containing austenitic alloy tube described in claim 2 , wherein the Cr-containing austenitic alloy tube is heated under the condition that the tube is held in the temperature range of 800 to 1200° C. for one minute or longer with flowing a nonoxidizing gas containing water vapor with a concentration of 250 to 25,000 ppm through the tube at a flow rate in the range of 6.0 to 50 L/min.

6. The Cr-containing austenitic alloy tube according to claim 1 , wherein the Cr-containing austenitic alloy tube is used as a member for a nuclear power plant.

7. A method for producing a Cr-containing austenitic alloy tube described in claim 6 , wherein the Cr-containing austenitic alloy tube is heated under the condition that the tube is held in the temperature range of 800 to 1200° C. for one minute or longer with flowing a nonoxidizing gas containing water vapor with a concentration of 250 to 25,000 ppm through the tube at a flow rate in the range of 6.0 to 50 L/min.

8. The method for producing a Cr-containing austenitic alloy tube according to claim 1 , wherein the Cr-containing austenitic alloy tube is heated under the condition that the tube is held in the temperature range of 800 to 1200° C. for one minute or longer with flowing a nonoxidizing gas containing water vapor with a concentration of 250 to 25,000 ppm through the tube at a flow rate in the range of 6.0 to 50 L/min.

Assignees

• Masaki Yasuhiro
• Tasaka Masahito
• Kanzaki Manabu
• Uehira Akihiro
• Kinomura Shoji
• Nippon Steel & Sumitomo Metal Corp

Inventors

• Masaki Yasuhiro
• Tasaka Masahito
• Kanzaki Manabu
• Uehira Akihiro
• Kinomura Shoji

Classifications

• C21D9/08

  for tubular bodies or pipes · CPC title

• C22C38/58

  with more than 1.5% by weight of manganese · CPC title

• F16L9/02

  of metal (F16L9/16 - F16L9/22 take precedence) · CPC title

• Y02E30/40

  Cross-Sectional Technologies · mapped topic

• C22C38/04

  containing manganese · CPC title