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Title:
PROCESS FOR PRODUCING SEAMLESS STEEL PIPE
Document Type and Number:
WIPO Patent Application WO/2005/115650
Kind Code:
A1
Abstract:
A round billet comprising 10.50 to 14.00% by mass of Cr and satisfying a value of not more than 9.0% as determined by a formula [Cr + 4Si - (22C + 0.5Mn + 1.5Ni + 30N)] wherein the symbol of element represents the content (% by mass) of each constituent element in the steel is heated under conditions of a soaking temperature of 1100 to 1250°C and an in-furnace time (min) of not less than “0.5 × diameter of round billet (mm)”. Thereafter, piercing and rolling are carried out under conditions of a piercer piercing efficiency of not less than 50%, a value of not more than 8.0 as specified by “&lcub (diameter of round billet - roll spacing at foremost end of plug)/diameter of round billet&rcub × 100”, and a plug shape of 0.06 to 0.17 as defined by &lcub radius of foremost end of plug (mm)/diameter of round billet (mm)&rcub ”. The high Cr seamless steel pipe thus obtained has no significant internal flaw, that is, has excellent internal properties.

Inventors:
Nakaike, Kouji c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Nakanishi, Tetsuya c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Nakata, Junji c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Application Number:
PCT/JP2005/009622
Publication Date:
December 08, 2005
Filing Date:
May 26, 2005
Export Citation:
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Assignee:
SUMITOMO METAL INDUSTRIES, LTD. (5-33, Kitahama 4-chome Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Nakaike, Kouji c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Nakanishi, Tetsuya c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Nakata, Junji c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
International Classes:
B21B19/04; B21B3/02; B21B17/14; B21B19/06; B21B23/00; (IPC1-7): B21B19/04
Foreign References:
JP2004043935A2004-02-12
JP2002361304A2002-12-17
JPH105820A1998-01-13
JP2003001305A2003-01-07
Other References:
See also references of EP 1757376A1
Attorney, Agent or Firm:
Honoue, Terutada (Honoue Patent Office, 17-23 Higashinaniwa-cho 5-chom, Amagasaki-shi Hyogo 92, 66008, JP)
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