A METHOD FOR MANUFACTURING TMCP THICK STEEL SHEET FOR CONSTRUCTION STRUCTURE WITH SUPERIOR YEILD RATIO

摘要

The present invention is built as a method of manufacturing a structural TMCP after the steel sheet, the steel Cu, Ni, and then subjected to the addition of alloy elements V and controlled rolling, by quenching the hot rolled steel sheet by generating a bainite structure organization low temperature strength and toughness is high to provide for a method for manufacturing a post-yield ratio high-level YP355 (N / ㎟) steel sheet, it is an object.; The invention C in weight%: 0.136 ~ 0.164%, Si: 0.40 ~ 0.50%, Mn: 1.00 ~ 1.25%, P: 0.012% or less, Nb: 0.025 ~ 0.035%, Ti: 0.015% or less, Cu: 0.30% or less, Ni: 0.30% or less, V: 0.020% or less, Ceq .: 0.42% or less, the balance Fe and other unavoidable impurities the steel slab containing, by re-heating and rolling in the temperature history of the non-recrystallized station immediately above, immediately above Ar ₃ temperature for 5 ~ 6 ℃ / cooled at a cooling rate of sec after the final temperature of the steel sheet so that the 600 ~ 550 ℃ air cooling the yield ratio superior TMCP method of producing a building structural after the steel sheet characterized in that in, the technical gist It shall be.