| 摘要 |
The subject of the invention is to provide a thick steel plate with little change in toughness before and after strain ageing, wherein the thick steel plate meets prescript chemical composition, and meets Delta G/[Si])0.4 and [Ti]*[N]>=4.0*10-5, and has a mixed composition with ferrite section ratio of 40-90 area% and Bainite section ration of 5-60 area%, also, the sum of ferrite section ratio+ Bainite section ration is more than 90 area%; the thick steel plate also has hard phase of more than 1 area%, and the effective grain diameter is 3-25 mu m. Besides, the quantity of solute C included by the total composition is below 0.035 quality%. |
