METHOD OF PRODUCING HIGH CR−BASED SEAMLESS STEEL TUBE

Title:

METHOD OF PRODUCING HIGH CR−BASED SEAMLESS STEEL TUBE

Document Type and Number:

WIPO Patent Application WO/2003/000938

Kind Code:

A1

Abstract:

A method of producing a high Cr−based seamless steel tube excellent in inner−surface quality efficiently and at low costs. Specifically, a method of producing a high Cr−based seamless steel tube, characterized by satisfying the following expression (b) when making a tube by using a blank containing 10−20% of Cr and up to 0.050% of S and P as impurities and by heating the blank and a billet to 1200 ° C with a billet soaking time set to St1 (time) and a blank soaking time to St2 (time): F = f &plus 0.6 ´ &lcub 1−1 &sol e^St1&rcub &plus 0.8 ´ &lcub 1−1&sol e^St2&rcub > −9.7 ... (b), where f is an indexed ease−of−producing−&dgr −ferrite that changes with component element contents. Accordingly, a high Cr−based seamless steel tube with a minimum of inner−surface flaw can be produced even a high Cr steel is used as a tube−making blank. Since there is no need of excessively reducing impurities as the composition of a blank and a specified productivity can be ensured when making a tube, a high Cr−based seamless steel tube excellent in inner−surface quality can be produced efficiently.

Inventors:

KIDANI SHIGERU (JP)
IKEDA KOICHI (JP)
ABE TOSHIHARU (JP)

Application Number:

PCT/JP2002/006256

Publication Date:

January 03, 2003

Filing Date:

June 21, 2002

Export Citation:

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Assignee:

SUMITOMO METAL IND (JP)
KIDANI SHIGERU (JP)
IKEDA KOICHI (JP)
ABE TOSHIHARU (JP)

International Classes:

C21D6/00; C21D8/10; C22C38/00; C22C38/24; C22C38/44; C22C38/46; C22C38/54; C22C38/58; C21D9/08; (IPC1-7): C21D8/10; C22C38/00; C22C38/58

Foreign References:

JPH04224659A	1992-08-13
JPH0277519A	1990-03-16
JPS60187426A	1985-09-24
JPH06306466A	1994-11-01
JPH08120336A	1996-05-14
JPH08232018A	1996-09-10

Other References:

See also references of EP 1413634A4
None

Attorney, Agent or Firm:

Mori, Michio (Sumitomoseimei-Amagasaki Bldg. 17-23, Higashinaniwa-cho 5-chom, Amagasaki-shi Hyogo, JP)

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