Production method for normalizing and rolling Q355MPa thick plate

Abstract

The invention belongs to the technical field of manufacturing of low-alloy high-strength steel, and discloses a production method for normalizing and rolling a Q355MPa thick plate, which is energy-saving, efficient and excellent in performance. Comprising the following steps that smelting and continuous casting are conducted to obtain a steel billet meeting set chemical components, and the steel billet comprises, by mass, 0.16%-0.18% of C, 0.2%-0.4% of Si, 1.4%-1.5% of Mn, 0.04%-0.05% of Nb, 0.04%-0.05% of V, 0.01%-0.03% of Ti and the balance Fe and inevitable impurities, P is smaller than or equal to 0.015%, and S is smaller than or equal to 0.005%; the steel billet is heated to the soaking zone temperature of 1200 + / -20 DEG C, and the heating time t is equal to (8-11 min) / 10 mm; the steel billet is subjected to two-stage rolling to form a steel plate, the initial rolling temperature of rough rolling ranges from 1050 DEG C to 1100 DEG C, the initial rolling temperature of finish rolling ranges from 810 DEG C to 830 DEG C, the final rolling temperature ranges from 780 DEG C to 820 DEG C, and the total reduction rate is larger than or equal to 70%; and rapid cooling is carried out within 10 seconds after finish rolling, so that the surface temperature of the steel plate is reduced to 680-720 DEG C, and then air cooling is carried out to the room temperature.

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