Title:
WELDED STEEL TUBE AND ITS MANUFACTURE
Document Type and Number:
Japanese Patent JP3518247
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide a steel tube having a superior seam quality and surface and having an excellent grooving resistance, as well as the manufacture of such tube using an induction heating method capable of high productivity.
SOLUTION: A steel strip 1 is preheated, continuously formed into an open tube 7 by a group of forming rolls 3; with both edges of the open tube 7 applied by edge preheating in the temperature range of not less than the Curie point or desirably not more than 1,300°C through induction heating, and by edge heating in the range of not less than 1,300°C and not more than the melting point also through induction heating; and then, abutted, pressure-welded by squeeze rolls, and formed into a steel tube 8. In this case, it is desirable that, after the pressure welding, the joined part is held at 1,300°C or above for 0.03sec or longer or for duration corresponding to oxygen concentration in the atmosphere. It is also desirable that the preheating of the steel strip 1 is carried out at 800°C or below and that the edge preheating, heating and pressure welding are performed in the atmosphere with the oxygen concentration lower than the air. As a result, an acceleration factor α becomes 1.4 or less in a corrosion test as the index of grooving resistance.
Inventors:
Toyooka, Takaaki
Itaya, Motoaki
Yorifuji, Akira
Onishi, Toshio
Hashimoto, Yuji
Tanaka, Nobuki
Sugie, Yoshinori
Sugano, Koji
Itaya, Motoaki
Yorifuji, Akira
Onishi, Toshio
Hashimoto, Yuji
Tanaka, Nobuki
Sugie, Yoshinori
Sugano, Koji
Application Number:
JP11709197A
Publication Date:
April 12, 2004
Filing Date:
May 07, 1997
Export Citation:
Assignee:
KAWASAKI STEEL CORP
International Classes:
B21C37/08; B21C37/083; B23K13/00; B23K20/00; B23K37/08; (IPC1-7): B23K20/00; B21C37/08; B21C37/083; B23K37/08
Other References:
日本鉄鋼協会，第３版鉄鋼便覧ＩＩＩ（２）条鋼・鋼管・圧延共通設備，日本，丸善株式会社，１９８０年１１月２０日，１１０２
Attorney, Agent or Firm:
小林 英一