Title:
ELECTRIC RESISTANCE WELDED STEEL PIPE PRIOR TO HEAT TREATMENT AND PROCESS FOR MANUFACTURING THE SAME
Document Type and Number:
WIPO Patent Application WO/2008/105216
Kind Code:
A1
Abstract:
An electric resistance welded steel pipe prior to heat treatment that even when subjected to rapid heating/quenching treatment like that for a hollow stabilizer or the like, realizes formation of members excelling in durability; and a process for manufacturing the electric resistance welded steel pipe. A steel sheet of composition containing, by mass, 0.15-0.40% C, 0.05-0.50% Si, 0.30-2.00% Mn, 0.01-0.10% Al, 0.001-0.04% Ti, 0.0005-0.0050% B and 0.0010-0.0100% N wherein Ti and N satisfy the relationship (N/14)<(Ti/47.9) is provided as a steel pipe material. The steel pipe material is formed into an approximately cylindrical open pipe. Open pipes at their end portions are abutted on each other and welded by high-frequency resistance welding so as to make a bond width of 30 to 65 μm. Thereafter, the resultant electric resistance welded steel pipe on its entirety is heated at temperature of Ac3-transformation point or higher and subjected to diameter reduction rolling of outer diameter ratio draft: (1-25/bond width before diameter reduction rolling (μm))x100% or greater. As a result, the width of reduced-carbon layer at electric resistance weld portion is reduced to a given value or less, so that even when subjected to rapid heating/quenching treatment, any decrease of quench hardness at electric resistance weld portion is suppressed to thereby provide members excelling in durability.
Inventors:
KAWABATA, Yoshikazu (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-ku, Tokyo 11, 1000011, JP)
河端良和 (〒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)
SAKAGUCHI, Masayuki (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-ku, Tokyo 11, 1000011, JP)
河端良和 (〒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)
SAKAGUCHI, Masayuki (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-ku, Tokyo 11, 1000011, JP)
Application Number:
JP2008/051596
Publication Date:
September 04, 2008
Filing Date:
January 25, 2008
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)
KAWABATA, Yoshikazu (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-ku, Tokyo 11, 1000011, JP)
河端良和 (〒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)
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)
KAWABATA, Yoshikazu (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-ku, Tokyo 11, 1000011, JP)
河端良和 (〒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)
International Classes:
C22C38/00; B21C37/08; B23K13/00; C21D8/10; C22C38/14; C22C38/58
Attorney, Agent or Firm:
OCHIAI, Kenichiro (7th floor Yanagiya building. 1-10, Nihonbashi 2-chom, Chuo-ku Tokyo 27, 1030027, JP)
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