METHOD FOR PRODUCING STEEL MATERIAL FOR HIGH HEAT INPUT WELDING

Japanese Patent JP2013112840

A

To provide a method for producing a steel material for high heat input welding, in which the toughness of a weld heat affected zone is not reduced even by the welding of an amount of welding heat input of 300 kJ/cm or more, on the assumption that it is produced by TMCP.

The component composition of steel includes, by mass, 0.005 to 0.02% of C, Si, Mn, P, S, Al, Ni, Nb, and Ti, and 0.0035 to 0.0070% of N, and Ca and B, and satisfies Ceq≤0.36. The steel material is heated and then rolled at a cumulative rolling reduction of 40% or more at a steel sheet surface temperature of 850°C or less. Finishing temperature: FT(°C) is FT(°C)≥790°C when Ti/N≤2.2, and FT(°C)≥(1065-125×Ti/N) and FT(°C)≥Ar₃ transformation point when Ti/N>2.2. Subsequently, accelerated cooling is performed at a cooling start-up temperature of (Ar₃-30)°C and a cooling shut-down temperature in the range of 300 to 500°C.

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YOKOTA TOMOYUKI
HASE KAZUKUNI
HISADA MITSUO

JP2011258927A

June 10, 2013

November 28, 2011

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JFE STEEL CORP

C21D8/02; C22C38/00; C22C38/14; C22C38/58

JP2002235114A	2002-08-23
JP2010159473A	2010-07-22
JP2002285239A	2002-10-03
JP2002235114A	2002-08-23

Shigeru Inoue
Kazuhiro Mori

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