Production of high tensile steel plate of low yield ratio

  • Inventors:
  • Assignees: Nippon Steel Corp
  • Publication Date: September 06, 1980
  • Publication Number: JP-S55115921-A

Abstract

PURPOSE:To produce the high tensile steel plate having low yield ratio, low surface hardness and superior weld joint toughness by hot-rolling and heat-treating the steel material containing slight amounts of Mo and V, under the specific conditions. CONSTITUTION:The steel which contains C; 0.01-0.15%, Si; 0.05-1.0%, Mn; 0.6-2.0%, Mo; 0.05-0.5%, V; 0.01-0.15%, Al; 0.01-0.1% or if necessary, small amounts of one or two or more kinds of Cu, Ni, Cr, Nb, Ti, Ca, B, Mg, REM. This steel material is hot rolled in such a manner that the cumulative draft at 900 deg.C or less becomes 50% or more with respect to the final product thickness, whereby the deposits of Mo and V are finely and evenly dispersed and deposited. Below Ar3 point, the rolling is finished. Next, it is cooled to a temperature below the Ar1 point, after which it is reheated and kept at 730-850 deg.C to the mixed structures of fine and stable gamma phase and the alpha of superior toughness around the same, whereby the weldable high tensile steel of low yield ratio and low surface hardness is produced.

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Cited By (7)

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    JP-H01156421-AJune 20, 1989Nippon Steel CorpManufacture of steel material having low yield ratio
    JP-H01156422-AJune 20, 1989Nippon Steel CorpManufacture of steel material having low yield ratio
    JP-H02282418-ANovember 20, 1990Kawasaki Steel CorpProduction of high tensile strength steel sheet excellent in internal quality and workability
    JP-H04202619-AJuly 23, 1992Kobe Steel LtdProduction of 60kgf/mm2 class steel plate excellent in welding crack resistance and having low yield ratio
    JP-H0581644-B2November 15, 1993Nippon Steel Corp
    JP-H0581645-B2November 15, 1993Nippon Steel Corp
    JP-H0747774-B2May 24, 1995株式会社神戸製鋼所耐溶接割れ性の優れた低降伏比60Kgf/mm▲上2▼級鋼板の製造方法