| 摘要 |
A process for the production of thick high-tensile-strength steel plates which comprises heating a bloom that contains by mass C: 0.03 to 0.055%, Mn: 3.0 to 3.5%, and Al: 0.002 to 0.10% with the contents of Mo, Si, V, Ti, and B being controlled to be 0.03% or less, 0.09% or less, 0.01% or less, 0.003 % or less, and 0.0003% or less respectively and that has a weld cracking par ameter (Pcm value) of 0.20 to 0.24% and a hardenability index(DI value) of 1 .00 to 2.60 to a temperature of 950 to 1100°C, rolling the heated bloom so a s to attain a cumulative rolling reduction of 70 to 90% in the temperature r ange of 850°C or above, rolling the obtained plate at 780°C or above so as t o attain a cumulative rolling reduction of 10 to 40% in the temperature rang e of 780 to 830°C, initiating the accelerated cooling of the resulting plate from a temperature of 700°C or above at a cooling rate of 8 to 80°C/sec, an d stopping the accelerated cooling at a temperature of room temperature to 3 50°C.
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