Title:
WELDED STEEL PIPE FOR LINEPIPE WITH SUPERIOR COMPRESSIVE STRENGTH AND EXCELLENT SOUR RESISTANCE, AND PROCESS FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2011/065582
Kind Code:
A1
Abstract:
A thick-walled steel pipe for linepipes which has high compressive strength and has sour resistance is provided by optimizing the metallographic structure of a steel plate without requiring special forming conditions for steel pipe formation or requiring any heat treatment after pipe production. The welded steel pipe for linepipes, which has superior compressive strength and excellent sour resistance, contains, in terms of mass%, 0.02-0.06% C, 0.01-0.5% Si, 0.8-1.6% Mn, up to 0.012% P, up to 0.0015% S, 0.01-0.08% Al, 0.005-0.050% Nb, 0.005-0.025% Ti, 0.0005-0.0035% Ca, and 0.0020-0.0060% N, C (%)-0.065Nb (%) being 0.025 or more, the value of CP being 0.95 or less, the value of Ceq being 0.28 or more, and the remainder comprising Fe and incidental impurities. The steel pipe has a metallographic structure which has a bainite content of 80% or more, an island martensite content of 2% or less, and an average bainite grain diameter of 5 µm or smaller.
Inventors:
ISHIKAWA, Nobuyuki (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
石川信行 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
TANIZAWA, Akihiko (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
谷澤彰彦 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
SUEYOSHI, Hitoshi (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
末吉仁 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
石川信行 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
TANIZAWA, Akihiko (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
谷澤彰彦 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
SUEYOSHI, Hitoshi (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
末吉仁 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
Application Number:
JP2010/071536
Publication Date:
June 03, 2011
Filing Date:
November 25, 2010
Export Citation:
Assignee:
JFE STEEL CORPORATION (2-3 Uchisaiwai-cho 2-chome, Chiyoda-ku Tokyo, 11, 〒1000011, JP)
JFEスチール株式会社 (〒11 東京都千代田区内幸町二丁目２番３号 Tokyo, 〒1000011, JP)
ISHIKAWA, Nobuyuki (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
石川信行 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
TANIZAWA, Akihiko (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
谷澤彰彦 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
SUEYOSHI, Hitoshi (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
JFEスチール株式会社 (〒11 東京都千代田区内幸町二丁目２番３号 Tokyo, 〒1000011, JP)
ISHIKAWA, Nobuyuki (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
石川信行 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
TANIZAWA, Akihiko (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
谷澤彰彦 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社 知的財産部内 Tokyo, 〒1000011, JP)
SUEYOSHI, Hitoshi (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
International Classes:
C22C38/00; B21B3/00; B21C37/08; B21C37/30; B23K9/025; B23K9/23; C21D8/02; C22C38/14; C22C38/58
Attorney, Agent or Firm:
OCHIAI, Kenichiro (JFE TECHNO-RESEARCH CORPORATION 7th Floor Yanagiya Building, 1-10, Nihonbashi 2-chome, Chuo-k, Tokyo 27, 〒1030027, JP)
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