| 摘要 |
PURPOSE: Provided is a method for manufacturing high strength and high ductility transformation induced plasticity steels (trip steel) with a tensile strength of higher than 90 kg/mm¬2 and superior press-formability by adding an appropriate amount of copper in a conventional steel composition for transformation induced plasticity steel. CONSTITUTION: The method for manufacturing high strength and high ductility transformation induced plasticity steels (trip steel) includes the steps of finish hot rolling a steel sheet comprising C 0.15 to 0.3 wt.%, Si 1.5 to 2.5 wt.%, Mn 0.6 to 1.8 wt.%, Al 0.02 to 0.10 wt.%, Cu 0.6 to 2.0 wt.%, Ni 0.6 to 2.0 wt.%, 0.01 wt.% or less of Ca, a balance of Fe and incidental impurities at 750-880°C; initiating water cooling in a temperature range of 680-740°C; stopping water cooling, wherein water cooling stop temperature is between 240x(wt.%Mn+wt.%Ni)-140(°C) and 540°C; and coiling the steel sheet.
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