Title:
MANUFACTURING METHOD FOR STEEL PIPE
Document Type and Number:
WIPO Patent Application WO/2011/161927
Kind Code:
A1
Abstract:
In the disclosed manufacturing method for a steel pipe, when quenching that is rapidly cooled after being heated is applied to a steel pipe, the pipe is heated to a quenching temperature defined by formula (1) by means of high frequency induction heating, and the time required from when the temperature of the pipe heated by high frequency induction heating has reached the temperature which is the transformation point of Ac3 to when rapid cooling is initiated is not more than 6 seconds if the quenching temperature is at least 975˚C, not more than 8 seconds if the quenching temperature is at least 950˚C but less than 975˚C, and not more than 9 seconds if the quenching temperature is less than 950˚C. Thus, the structure of the steel pipe undergoes complete Martensite transformation, and a highly strong and tough steel pipe can be obtained because the crystal grains are miniaturised. In formula (1) T1 is the quenching temperature (˚C), TAc3 is the Ac3 transformation point temperature (˚C). (1)TAc3+40˚C≤T1≤1000˚C…
Inventors:
UCHIDA, Kazuhiro (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
Application Number:
JP2011/003495
Publication Date:
December 29, 2011
Filing Date:
June 20, 2011
Export Citation:
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)
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)
International Classes:
C21D9/08; C21D1/10; C21D1/18; B60R21/268; C22C38/00; C22C38/44
Attorney, Agent or Firm:
MORI, Michio et al. (M. MORI PATENT OFFICE, 17-23 Higashinaniwa-cho 5-chome, Amagasaki-sh, Hyogo 92, 〒6600892, JP)
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