METHOD FOR MANUFACTURING THICK-WALLED SEAMLESS STEEL PIPE

Title:

METHOD FOR MANUFACTURING THICK-WALLED SEAMLESS STEEL PIPE

Document Type and Number:

WIPO Patent Application WO/2011/021396

Kind Code:

A1

Abstract:

When quenching and tempering heat treatments are performed on a steel pipe that has undergone a pipe forming process by thermal processing and has a wall thickness exceeding 30 mm, the following processes are sequentially performed: (a) a quenching process in which, in the temperature range of at least 750 ˚C or more at a heating stage, the steel pipe is heated to a temperature of 900 1000 ˚C inclusive, using induction heating at a frequency of 200 Hz or less as a heating means, and then is quenched by water-cooling; and (b) a tempering process in which the steel pipe is tempered at a temperature of 500 750 ˚C inclusive. This makes it possible to perform uniform and high-speed heating in the quenching process, reduce the size of crystal grains, and therefore obtain a thick-walled seamless steel pipe with good toughness. In the quenching process (a), after heating by the induction heating, it is preferable to further perform a uniform heat treatment in the temperature range of 900 1000 ˚C inclusive for 10 minutes or less and then perform quenching by water-cooling.

Inventors:

KONDO KUNIO (JP)
ARAI YUJI (JP)

Application Number:

PCT/JP2010/005134

Publication Date:

February 24, 2011

Filing Date:

August 20, 2010

Export Citation:

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Assignee:

SUMITOMO METAL IND (JP)
KONDO KUNIO (JP)
ARAI YUJI (JP)

International Classes:

C21D9/08; C21D1/10; C21D1/18

Foreign References:

JPS62270725A	1987-11-25
JPH04191326A	1992-07-09
JPH08104922A	1996-04-23
JP2006274350A	2006-10-12
JP2001205351A	2001-07-31
JPH08104922A	1996-04-23
JP2007154289A	2007-06-21
JPS6428328A	1989-01-30
JPS60116725A	1985-06-24
JPH1024320A	1998-01-27

Other References: