STEEL FOR LARGE HEAT INPUT WELDING FOR EARTHQUAKE RESISTANT BUILDING

• Main Authors: KOSEKI TOSHIHIKO, HATA TOMOHIKO, ISHIKAWA TADASHI, NAGAHARA MASAAKI
• Format: Patent
• Language: English
• Published: 18.09.2001
• Edition: 7
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; METALLURGY; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide a steel for large heat input welding for earthquake resistant building excellent in heat affected zone toughness by prescribing the chemical components values of Ti and N, the grain sizes of TiN and AlN and the number of grains having the same grain sizes for securing HAZ toughness in steel by TiN application. SOLUTION: In this steel having the components of, by mass, 0.07 to 0.20% C, 0.10 to 0.50% Si, 0.80 to 2.0% Mn, <=0.025% P, <=0.025% S, 0.001 to 0.06% Al, 0.002 to 0.02% Ti and <=0.003% N, and the balance iron with inevitable impurities and, in which Ti/N also satisfies 1.0 to 6.0, moreover, TiN with a grain size of 0.01 to 0.1 μm is present by 5×105 to 5×106 pieces/mm2 in the steel before welding, and also, AlN with a grain size of >=0.01 μm is present by <=5×102 pieces/mm2.