Austenitic stainless steel tube excellent in steam oxidation resistance and a manufacturing method thereof
AssigneeSumitomo Metal Industries, Ltd.
InventorAtsuro Iseda
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Abstract
The present invention provides an austenitic stainless steel tube with a uniform fine grained structure of regular grains, which is not changed to a coarse structure and the steam oxidation resistance is maintained even if the tube is subjected to a high temperature reheating during welding and high temperature bending working. The austenitic stainless steel tube consists of, by mass %, C: 0.03–0.12%, Si: 0.1–0.9%, Mn: 0.1–2%, Cr: 15–22%, Ni: 8–15%, Ti: 0.002–0.05%, Nb: 0.3–1.5%, sol. Al: 0.0005–0.03%, N: 0.005–0.2% and O (oxygen): 0.001–0.008%, and the balance Fe and impurities, the austenitic stainless steel tube having austenitic grain size number of 7 or more and a mixed grain ratio of preferably 10% or less.
Claims8
An austenitic stainless steel tube excellent in steam oxidation resistance, characterized by consisting of, by mass %, C:
- 0.03–0.12%, Si:
- 0.1–0.9%, Mn:
- 0.1–2%, Cr:
- 15–22%, Ni:
- 8–15%, Ti:
- 0.002–0.05%, Nb:
- 0.3–1.5%, sol.Al:
- 0.0005–0.03%, N:
- 0.005–0.2% and O (oxygen):
- 0.001–0.008%, and the balance Fe and impurities, and also characterized by an entire structure having a uniform fine-grained structure wherein austenitic grain size is ASTM No. 7 or more.
An austenitic stainless steel tube excellent in steam oxidation resistance, characterized by consisting of, by mass %, C:
- 0.03–0.12%, Si:
- 0.1–0.9%, Mn:
- 0.1–2%, Cr:
- 15–22%, Ni:
- 8–15%, Ti:
- 0.002–0.05%, Nb:
- 0.3–1.5%, sol.Al:
- 0.0005–0.03%, N:
- 0.005–0.2% and O (oxygen):
- 0.001–0.008%, and at least one alloying element selected from at least one group mentioned below, and the balance Fe and impurities, and also characterized by an entire structure having a fine grained structure wherein austenitic grain size is No. 7 or more,
- the first group:
- Ca, Mg, Zr, B, Pd, Hf and REM of 0.0001–0.2 mass % respectively, and
- the second group:
- Cu, Mo and W of 0.01–5 mass % respectively.
An austenitic stainless steel tube excellent in steam oxidation resistance, characterized by consisting of, by mass %, C:
- 0.03–0.12%, Si:
- 0.1–0.9%, Mn:
- 0.1–2%, Cr:
- 15–22%, Ni:
- 8–15%, Ti:
- 0.002–0.05%, Nb:
- 0.3–1.5%, sol.Al:
- 0.0005–0.03%, N:
- 0.005–0.2% and O (oxygen):
- 0.001–0.008%, and the balance Fe and impurities, and also characterized by an entire structure having a fine grained structure wherein austenitic grain size is No. 7 or more and a mixed grain ratio is 10% or less.
An austenitic stainless steel tube excellent in steam oxidation resistance, characterized by consisting of, by mass %, C:
- 0.03–0.12%, Si:
- 0.1–0.9%, Mn:
- 0.1–2%, Cr:
- 15–22%, Ni:
- 8–15%, Ti:
- 0.002–0.05%, Nb:
- 0.3–1.5%, sol.Al:
- 0.0005–0.03%, N:
- 0.005–0.2% and O (oxygen):
- 0.001–0.008%, and at least one alloying element selected from at least one group mentioned below, and the balance Fe and impurities, and also characterized by an entire structure having a fine grained structure wherein austenitic grain size is No. 7 or more and a mixed grain ratio is 10% or less,
- the first group:
- Ca, Mg, Zr, B, Pd, Hf and REM of 0.0001–0.2 mass % respectively, and
- the second group:
- Cu, Mo and W of 0.01–5 mass % respectively.
Dependencies are inferred from the claim text.