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Title:
METHOD FOR PRODUCING HIGH ALLOY STEEL PIPE
Document Type and Number:
WIPO Patent Application WO/2010/070990
Kind Code:
A1
Abstract:
Disclosed is a method for producing a high alloy steel pipe having a minimum yield strength of 758.3-965.2 MPa, wherein a high alloy steel base pipe having a chemical composition, which contains in mass%, 0.03% or less of C, 1.0% or less of Si, 0.3-5.0% of Mn, 25-40% of Ni, 20-30% of Cr, 0-4% of Mo, 0-3% of Cu and 0.05-0.50% of N, with the balance made up of Fe and unavoidable impurities, is produced by hot forming and optionally by a solution treatment, and then the thus-produced base pipe is subjected to cold rolling, thereby producing a high alloy steel pipe.  The method for producing a high alloy steel pipe is characterized in that the reduction ratio (Rd) in terms of reduction of the cross-sectional area during the final cold rolling process is within the range of more than 30% but not more than 80%, and that the cold rolling is carried out under the conditions satisfying the following formula (1).    Rd (%) ≥ (MYS - 520)/3.1 - (Cr + 6 × Mo + 300 × N)        (1) In the formula, Rd and MYS respectively represent the reduction ratio (%) in terms of reduction of the cross-sectional area and the target yield strength (MPa), and Cr, Mo and N represent the contents (mass%) of the respective elements.

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Inventors:
SUWABE, Hitoshi (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
諏訪部　均 (〒41 大阪府大阪市中央区北浜四丁目５番３３号　住友金属工業株式会社内 Osaka, 〒5410041, JP)
Application Number:
JP2009/068954
Publication Date:
June 24, 2010
Filing Date:
November 06, 2009
Export Citation:
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Assignee:
SUMITOMO METAL INDUSTRIES, LTD. (5-33, Kitahama 4-chome Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
住友金属工業株式会社 (〒41 大阪府大阪市中央区北浜四丁目５番３３号 Osaka, 〒5410041, JP)
SUWABE, Hitoshi (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
International Classes:
C21D8/10; B21B21/00; B21C1/22; B21C23/08; C22C38/00; C22C38/58
Attorney, Agent or Firm:
SUGIOKA, Kanji et al. (K. SUGIOKA PATENT OFFICE, 2-5-10 Sonezaki, Kita-ku, Osaka-sh, Osaka 57, 〒5300057, JP)
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