Title:
WELDED STEEL PIPE AND ITS PRODUCTION
Document Type and Number:
Japanese Patent JP3331825
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To produce a welded steel pipe small in flaws in the structure of the welding part, at the time of forming a steel strip into an open pipe and welding the edge parts over against each other to produce a welded steel pipe, by limiting the content of O to the content of C in the welding solidified part.
SOLUTION: An open tubular body 1 is formed of a steel strip contg., by weight, 0.01 to 0.5% C, <1% Si, 0.05 to 20% Mn and <6% Cr, the edge parts of the tubular body are butted under heating by energizing by a contact tip 2, the butted part is irradiated with a laser beam 3a from a laser light source 3, furthermore, the upper end of the tubular body 1 is pressed by a top roll 4, upsetting is executed by a side roll 5, and the butted part is welded to form into a welded steel pipe, which is quenched and tempered by high frequency heating devices 6 and 8 and a water cooling zone 7. At this time, in the case the C content in the welding solidified part is ≤0.2%, [C content]×[O content] in the welding solidified structure is regulated to ≤0.006, and in the case the C content is ≥0.2% [O content] is limited to ≤0.03, by which the formation of blowing flaws caused by the generation of gaseous CO and CO2 in the welding part can be prevented.
Inventors:
Moriaki Ono
Takeshi Shiozaki
Masaki Ohmura
Hiroshi Nagahama
Akio Sato
Kenichi Iwasaki
Takeshi Shiozaki
Masaki Ohmura
Hiroshi Nagahama
Akio Sato
Kenichi Iwasaki
Application Number:
JP20332795A
Publication Date:
October 07, 2002
Filing Date:
August 09, 1995
Export Citation:
Assignee:
Nippon Steel Tube Co., Ltd.
International Classes:
B21C37/08; B23K26/00; B23K26/20; C22C38/00; C22C38/18; (IPC1-7): B21C37/08; B23K26/00; C22C38/00; C22C38/18
Domestic Patent References:
| JP6264486A | ||||
| JP6116645A |
Attorney, Agent or Firm:
Takehiko Suzue (4 outside)