STEEL EXCELLING IN TOUGHNESS AT REGION AFFECTED BY WELDING HEAT

• Main Authors: NAGAI, YOSHIHIDE, UEMORI, RYUJI, WATANABE, YOSHIYUKI, FUKUNAGA, KAZUHIRO, CHIJIIWA, RIKIO
• Format: Patent
• Language: English; French; German
• Published: 20.05.2009
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

The present invention is a steel excellent in toughness of a weld heat affected zone characterized by containing, by mass%, C: 0.02 to 0,06%, Si: 0.05 to 0.30%, Mn: 1.7 to 2.7%, P: 0.015% or less, S: 0.010% or less, Ti: 0.005 to 0.015%, O: 0.0010 to 0.0045, and N: 0.0020 to 0.0060% and comprising a balance of iron and unavoidable impurities, having an amount of intermixture of impurities limited to Al: 0.004% or less, Nb: 0.003% or less, and V: 0.030% or less, and having a CeH represented by formula (A) in the range of 0.04 or less: CeH = C + 1 / 4 ¢ Si - 1 / 24 ¢ Mn + 1 / 48 ¢ Cu + 1 / 32 ¢ Ni + 1 / 0.4 ¢ Nb + 1 / 2 ¢ V where, C, Si, Mn, Cu, Ni, Nb, and V show steel compositions (mass%).