METHOD FOR PRODUCING STEEL CONDUIT TUBE AND HIGH SI COMPONENT OR HIGH CR COMPONENT STEEL CONDUIT TUBE

Title:

METHOD FOR PRODUCING STEEL CONDUIT TUBE AND HIGH SI COMPONENT OR HIGH CR COMPONENT STEEL CONDUIT TUBE

Document Type and Number:

WIPO Patent Application WO/2008/108450

Kind Code:

A1

Abstract:

A method for producing a steel conduit tube in which welding defect resulting from oxides can be reduced stably by plasma irradiation and plasma jet sound can be reduced. When a steel plate (1) is shaped into a tube and its abutting end faces (4) are subjected to conduit tube welding, reductive high temperature (false) laminar flow plasma produced by applying a voltage to reductive mixture gas containing 2-50 vol% of H2 gas and the remainder of Ar gas added or not added with N2 gas and/or He gas is blown at least to the abutting end face (4a) out of a region (6) where the temperature becomes 650°C or above on the welding upstream side of a welding point (9). The applying voltage exceeds 120V and the plasma blow conditions preferably satisfy following expression (1).

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Inventors:

HAMATANI HIDEKI (JP)
KODAMA SHINJI (JP)
MIZUHASHI NOBUO (JP)
TAKEUCHI SUNAO (JP)
NAKAJI TOMOHIRO (JP)
MIYAKAWA TAKASHI (JP)
ASAHI HITOSHI (JP)
TANIMOTO MICHITOSHI (JP)
MUKAI MICHIMASA (JP)

Application Number:

PCT/JP2008/054100

Publication Date:

September 12, 2008

Filing Date:

February 29, 2008

Export Citation:

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Assignee:

NIPPON STEEL CORP (JP)
HAMATANI HIDEKI (JP)
KODAMA SHINJI (JP)
MIZUHASHI NOBUO (JP)
TAKEUCHI SUNAO (JP)
NAKAJI TOMOHIRO (JP)
MIYAKAWA TAKASHI (JP)
ASAHI HITOSHI (JP)
TANIMOTO MICHITOSHI (JP)
MUKAI MICHIMASA (JP)

International Classes:

B21C37/08; B23K13/00; B23K13/06

Foreign References:

JP2006026691A	2006-02-02
JP2005230909A	2005-09-02
JPH1080718A	1998-03-31

Other References: