HIGH-STRENGTH STEEL PIPE WITH EXCELLENT LOW-TEMPERATURE TOUGHNESS FOR LINE PIPE, HIGH-STRENGTH STEEL PLATE FOR LINE PIPE, AND PROCESSES FOR PRODUCING THESE

WIPO Patent Application WO/2008/004680

A1

A high-strength steel pipe for line pipes which is inhibited from decreasing in HAZ toughness and has excellent low-temperature toughness; a process for producing the steel pipe; a high-strength steel plate for line pipes which is for use as a raw material for the high-strength steel pipe for line pipes; and a process for producing the steel plate. The high-strength steel pipe for line pipes which has excellent low-temperature toughness is characterized in that the composition of the base metal contains, in terms of mass%, 0.020-0.080% C, 0.01-0.50% Si, 0.01-0.15% Mo, 0.0005-0.030% Al, and 0.0001-0.030% Nb, provided that C+0.25Si+0.1Mo+Al+Nb is 0.100% or less, and that former austenite grain boundaries in the part which was influenced by welding heat and has been reheated have an austenite/martensite mixture which has a width of 10 µm or smaller and a length of 50 µm or smaller.

JP2548067	LOW ALLOY STEEL WITH HIGH TOUGHNESS
WO/2023/188576	SLIDING MEMBER AND INTERNAL COMBUSTION ENGINE PROVIDED WITH SLIDING MEMBER

HARA TAKUYA (JP)
ASAHI HITOSHI (JP)
TERADA YOSHIO (JP)

PCT/JP2007/063615

January 10, 2008

July 02, 2007

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NIPPON STEEL CORP (JP)
HARA TAKUYA (JP)
ASAHI HITOSHI (JP)
TERADA YOSHIO (JP)

C22C38/00; B23K35/30; C21D8/02; C21D8/10; C21D9/08; C21D9/50; C22C38/14; C22C38/58

JP2006028627A	2006-02-02
JPS624826A	1987-01-10
JPH10298707A	1998-11-10
JP2001303191A	2001-10-31
JP2004052104A	2004-02-19
JP2004068055A	2004-03-04
JP2004099930A	2004-04-02

See also references of EP 2036995A4

AOKI, Atsushi et al. (Toranomon 37 Mori Bldg.5-1, Toranomon 3-chom, Minato-ku Tokyo 23, JP)

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