| 摘要 |
PURPOSE: A high-strength thick steel plate with a good drop weight property and good base toughness is provided to micronize a diagonal grain diameter by the right control of the chemical composition of the steel and to ensure good base toughness for a thick steel plate. CONSTITUTION: A high-strength thick steel plate with a good drop weight property and good base toughness consists of C of 0.1~0.16 mass%, Si of 0.05~0.5 mass%, Mn of 0.9~1.6 mass%, Al of 0.01~0.06 mass%, Mo of 0.13~0.3 mass%, B of 0.0005~0.002 mass%, Fe and inevitable impurities. The steel plate comprises at least one of Cr of 0.3 mass% or less or V of 0.07 mass% or less. The steel plate consists of a tempering bainite structure. The diameter of the tempering bainite structure of 4μm or less. Because the crystal grain of the tempering bainite structure has two crystal orientation differences, it is surrounded by a diagonal grain with 15° or more.
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